記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nano Letters  

Thickness control of two-dimensional (2D) metal nanosheets (metallenes) has scientific significance for energy and catalyst applications, yet is unexplored owing to the lack of an efficient approach for the tailored synthesis of metallenes with controlled atomic layers. Here we report a 2D template-directed synthesis of ultrathin Pd nanosheets with well-controlled thicknesses. Molecularly thin single-crystalline Pd nanosheets with well-defined hexagonal morphologies were synthesized via a one-pot method with 2,4,6-trichlorophenyl formate. Such Pd nanosheets were used as hard templates for the tailored synthesis of the Pd nanosheets with controlled thicknesses (9, 11, 13, and 15 atomic layers). Hard X-ray photoelectron spectroscopy and density functional theory calculations revealed unique electronic states in thickness-controlled Pd nanosheets; these states included reduced surface charges to bulk, increased work functions, and decreased d-band centers. Thus, atomic layer engineering of Pd nanosheets enabled the fine-tuning of the surface electronic states to improve the hydrogen evolution reaction.

DOI： 10.1021/acs.nanolett.4c02741

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Communications  

As a member of 2D family, amorphous 2D nanosheets have received increasing attention due to their unique properties that are distinct from crystalline 2D nanosheets. However, compared with the vast library of crystalline 2D nanosheets, amorphous 2D nanosheets are still infancy due to the lack of an efficient synthetic approach. Here, we present a strategy that yields a library of 10 distinct amorphous 2D metal oxides/oxyhydroxides using solid-state surfactant crystals. A key feature of this process is a stepwise reaction using solid surfactant; the solid-state surfactant crystals have metal ions arranged in the interlayer space, and hydrolysis of the metal ions leads to the formation of isolated clusters in the surfactant crystals via limited condensation reactions. Immersing the surfactant crystals in formamide promotes nanosheet formation through the self-assembly of clusters by templating the morphologies of the crystals generated from surfactants crystals. Our approach opens a flatland in amorphous 2D world.

DOI： 10.1038/s41467-024-51040-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Small  

In 2D materials, a key engineering challenge is the mass production of large-area thin films without sacrificing their uniform 2D nature and unique properties. Here, it is demonstrated that a simple fluid phenomenon of water/alcohol solvents can become a sophisticated tool for self-assembly and designing organized structures of 2D nanosheets on a water surface. In situ, surface characterizations show that water/alcohol droplets of 2D nanosheets with cationic surfactants exhibit spontaneous spreading of large uniform monolayers within 10 s. Facile transfer of the monolayers onto solid or flexible substrates results in high-quality mono- and multilayer films with high coverages (>95%) and homogeneous electronic/optical properties. This spontaneous spreading is quite general and can be applied to various 2D nanosheets, including metal oxides, graphene oxide, h-BN, MoS<inf>2</inf>, and transition metal carbides, enabling on-demand smart manufacture of large-size (>4 inchϕ) 2D nanofilms and free-standing membranes.

DOI： 10.1002/smll.202403915

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その他リンク： https://onlinelibrary.wiley.com/doi/pdf/10.1002/smll.202403915

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.inorgchem.3c03789

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Physics Express  

We present a new approach for designing thermal shielding materials using two-dimensional oxide nanosheets. Our approach uses hetero-assembly design [(Ti<inf>0.87</inf>O<inf>2</inf>)<inf>m </inf>(Cs<inf>2.7</inf>W<inf>11</inf>O<inf>35−d </inf>)<inf>20</inf> (m = 0, 5, 10)] by overlaying high refractive index (n) Ti<inf>0.87</inf>O<inf>2</inf> nanosheets with transparent conducting Cs<inf>2.7</inf>W<inf>11</inf>O<inf>35−d </inf> nanosheets. Through proper design of the thickness of high-n Ti<inf>0.87</inf>O<inf>2</inf> layers, we achieved the optimum thermal shielding properties with a high NIR reflectance (>46%), a high visible transparency (>76%) and a neutral color in an ultrathin form (<60 nm). Our nanosheet approach is of technological importance for exploring new thermal shielding materials.

DOI： 10.35848/1882-0786/ad13ce

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Sustainable Energy and Fuels  

CuLi<inf>1/3</inf>Ti<inf>2/3</inf>O<inf>2</inf> (CLTO) is a visible-responsive photocatalyst, whose photo-response reaches up to 600 nm, for H<inf>2</inf> evolution using sacrificial electron donors such as methanol and S²⁻. In this study, utilization of CLTO in Z-scheme water splitting (Z-WS) was investigated. The photocatalytic performance of Cr<inf>2</inf>O<inf>3</inf>/M/CLTO as a H<inf>2</inf>-evolving photocatalyst, which was prepared by sequential photodeposition of cocatalysts (M: Ru, Rh, Pd and Pt) and Cr<inf>2</inf>O<inf>3</inf>, was evaluated for Z-WS using BiVO<inf>4</inf>, an O<inf>2</inf>-evolving photocatalyst, and a Co(bpy)<inf>3</inf>^3+/2+ redox shuttle under visible light. Among the examined samples, Cr<inf>2</inf>O<inf>3</inf>/Ru/CLTO produced both H<inf>2</inf> and O<inf>2</inf> with meaningful rates. Thus, CLTO was first utilized in a visible responsive Z-scheme system for water splitting. The Cr<inf>2</inf>O<inf>3</inf> layer played a significant role in the suppression of backward reactions, such as reduction of Co(bpy)<inf>3</inf>³⁺. The activity of Cr<inf>2</inf>O<inf>3</inf>/Ru/CLTO for Z-WS was remarkably affected by the deposition conditions of the Ru cocatalyst. The activity for Z-WS was remarkably improved when the photodeposition of the Ru cocatalyst was conducted in a methanol solution of RuCl<inf>3</inf>. Unusually large plate Ru species with 100-200 nm sizes and about 30 nm thickness were present in the highly active sample. Characterization using X-ray photoelectron spectroscopy and X-ray absorption spectroscopy indicated that the Ru cocatalyst was deposited as mainly the oxyhydroxide of Ru. Z-WS also proceeded in the absence of Co(bpy)<inf>3</inf>^3+/2+ (the system based on interparticle electron transfer), however, the Z-scheme system using the Co(bpy)<inf>3</inf>^3+/2+ electron shuttle showed 10 times higher activity than the interparticle electron transfer system. The external quantum yield and efficiency of solar energy conversion to hydrogen were determined to be 0.5% at 430 nm and 0.029%, respectively.

DOI： 10.1039/d3se01622f

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Dalton Transactions  

Pb-based perovskites play pivotal roles in ferroelectric research. In the search for new Pb-based ferroelectrics, we investigated the ferroelectric properties of Dion-Jacobson type CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> and exfoliated 2D nanosheets. Ferroelectricity in CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> was demonstrated for the first time. CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> adopted a polar tetragonal structure with a modest T<inf>C</inf> = 260 °C and polarization P<inf>S</inf> = 7.93 μC cm⁻²; the polarization mainly arose from the out-of-plane displacements of Nb⁵⁺ ions and nearby oxygens. CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> layered perovskite offers additional advantages for tailoring ferroelectric nanomaterials, as exfoliated 2D nanosheets provide novel platforms for investigating ferroelectric properties down to the 2D limit. Piezoresponse force microscopy confirmed stable ferroelectricity even in exfoliated 2D Pb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> nanosheets.

DOI： 10.1039/D4DT02343A

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Nano  

As a member of the 2D materials family, 2D metal nanosheets (metallenes) have received increasing attention due to their intriguing properties distinct from those of graphene and other inorganic 2D nanosheets. However, the synthesis of metallenes is still challenging, owing to the lack of an efficient synthetic approach. Here we present a facile one-pot approach to the controlled synthesis of Pd nanosheets. A key feature of this process is a stepwise reaction using 2,4,6-trichlorophenyl formate (TCPF); TCPF emits carbon monoxide gas, which acts as both a reductant and a surface capping agent, promoting the anisotropic 2D growth of the Pd nanosheets. Photoemission spectroscopy revealed some peculiar features of the surface charge and valence band states due to suppressed electron transfer at the 2D surface. This surface state caused improved catalytic activity for the hydrogen evolution reaction compared to that of bulk Pd.

DOI： 10.1021/acsnano.3c07861

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Nano  

Thermal shielding materials that can block near-infrared (NIR) light from the sunlight while maintaining visible transparency have become increasingly important from an energy-saving perspective. Here, we demonstrate a gigantic NIR shielding by an engineered plasmonic material based on a two-dimensional (2D) polytungstate (Cs<inf>4-x</inf>W<inf>11</inf>O<inf>35-d</inf>). Starting from a charge-neutral polytungstate (Cs<inf>4</inf>W<inf>11</inf>O<inf>35</inf>), we synthesize charge-imbalanced 2D nanosheets (Cs<inf>4-x</inf>W<inf>11</inf>O<inf>35-d</inf>) that undergo an unusual structural change with the semiconductor-to-metal transition in a reduced atmosphere. Layer-by-layer engineering of the 2D nanosheets enables a plasmon-induced enhancement of the NIR reflectance (>53%) with a high visible transparency (>71%), realizing high-performance thermal shielding. Our approach offers a solution for future thermal management technology.

DOI： 10.1021/acsnano.3c00815

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nano Letters  

Dielectric capacitors have greater power densities than batteries, and, unlike batteries, they do not utilize chemical reactions during cycling. Thus, they can become ideal, safe energy storage devices. However, dielectric capacitors yield rather low energy densities compared with other energy storage devices such as batteries and supercapacitors. Here, we present a rational approach for designing ultrahigh energy storage capacitors using two-dimensional (2D) high-κ dielectric perovskites (Ca<inf>2</inf>Na<inf>m-3</inf>Nb<inf>m</inf>O<inf>3m+1</inf>; m = 3-6). Individual Ca<inf>2</inf>Na<inf>m-3</inf>Nb<inf>m</inf>O<inf>3m+1</inf> nanosheets exhibit an ultrahigh dielectric strength (638-1195 MV m^-1) even in the monolayer form, which exceeds those of conventional dielectric materials. Multilayer stacked nanosheet capacitors exhibit ultrahigh energy densities (174-272 J cm^-3), high efficiencies (>90%), excellent reliability (>10⁷ cycles), and temperature stability (−50-300 °C); the maximum energy density is much higher than those of conventional dielectric materials and even comparable to those of lithium-ion batteries. Enhancing the energy density may make dielectric capacitors more competitive with batteries.

DOI： 10.1021/acs.nanolett.3c00079

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Two kinds of single-crystalline oxyfluoride nanosheets were synthesized by exfoliation of layered bismuth oxyfluorides intercalated with nitrates. The solution-based exfoliation process produced multilayered cationic oxyfluoride nanosheets with thicknesses of several nanometers. A second harmonic generation measurement clarified that one of the nanosheets had a noncentrosymmetric structure. This is the first example of a cationic nanosheet with nonlinear optical properties.

DOI： 10.1246/cl.230136

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

We demonstrated the synthesis of amorphous oxide nanosheets from crystalline nanosheets prepared by the exfoliation of layered compounds. Single-crystalline oxide nanosheets were calcined with C<inf>3</inf>N<inf>4</inf> powder in flowing nitrogen and annealed in air to produce amorphous oxide nanosheets. The cation composition and valence, shape, lateral size, surface roughness, and thickness were not changed by treatment. This approach enables the production of amorphous oxide nanosheets with distinct morphologies and compositions and large lateral sizes.

DOI： 10.1246/cl.230073

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

We present a new approach for designing flexible energy storage capacitors using two-dimensional (2D) inorganic nanosheets. 2D dielectric Ca<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> nanosheet and ferroelectric poly(vinylidene fluoride) (PVDF) were selected as model material systems. LangmuirBlodgett deposition was utilized for layer-by-layer engineering of (Ca<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>/PVDF) nanocomposite films on an indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrate. Such a new composite design realized the simultaneous improvement of energy density (³7 J cm¹³) and efficiency (³78 %) even in the ultrathin form (³20 nm) on the ITO-coated PET substrate. Nanosheet-based flexible capacitors also maintained a stable performance even after 10⁴ times bending cycles. These results indicate that our nanosheet approach is of technological importance for exploring new flexible dielectric capacitors.

DOI： 10.2109/jcersj2.22150

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

The effective application of 2D materials is strongly dependent on the mass production of high-quality large-area 2D thin films. Here, we demonstrate a strategy for the automated manufacturing of high-quality 2D thin films using a modified drop-casting approach. Our approach is simple; by using an automated pipette, a dilute aqueous suspension is dropped onto a substrate heated on a hotplate, and controlled convection by Marangoni flow and liquid removal causes the nanosheets to come together to form a tile-like monolayer film in 1-2 min. Ti<inf>0.87</inf>O<inf>2</inf> nanosheets are utilized as a model system for investigating the control parameters such as concentrations, suction speeds, and substrate temperatures. We perform the automated one-drop assembly of a range of 2D nanosheets (metal oxides, graphene oxide, and hexagonal boron nitride) and successfully fabricate various functional thin films in multilayered, heterostructured, and sub-micrometer-thick forms. Our deposition method enables on-demand large-size (>2 inchϕ) manufacturing of high-quality 2D thin films while reducing the time and sample consumption.

DOI： 10.1021/acsami.3c02250

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Small  

Recent progress in 2D materials has initiated new fields of molecularly thin amorphous materials with mysterious properties and structures. However, designed synthesis of molecularly thin amorphous silica still remains a challenge; whether free-standing molecularly thin amorphous silica nanosheets can exist is unclear. Here, this issue is addressed by using a new chemical protocol; solid-state surfactant lamellae with ordered alkyl-chain arrangements can serve as superior templates guiding free-standing amorphous silica nanosheets. Simple sonication of the lamellar hybrids allows exfoliation into monolayer amorphous silica nanosheets with 0.9 nm thickness. In addition, the nanosheets show the distinctive feature of high colloidal stability that enables atomic layer engineering of silica nanocoatings and dielectric nanofilms. The approach may shed new light on the properties and applications of old silica.

DOI： 10.1002/smll.202300022

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/smll.202300022

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/aelm.202201239

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Scientific Reports  

Desired electrode patterning on two-dimensional (2D) materials is a foremost step for realizing the full potentials of 2D materials in electronic devices. Here, we introduce an approach for damage-free, on-demand manufacturing of 2D material devices using light-emitting diode (LED) lithography. The advantage of this method lies in mild photolithography by simply combining an ordinary optical microscope with a commercially available LED projector; the low-energy red component is utilized for optical characterization and alignment of devices, whereas the high-energy blue component is utilized for photoresist exposure and development of personal computer designed electrode patterns. This method offers maskless, damage-free photolithography, which is particularly suitable for 2D materials that are sensitive to conventional lithography. We applied this LED lithography to device fabrication of selected nanosheets (MoS<inf>2</inf>, graphene oxides and RuO<inf>2</inf>), and achieved damage-free lithography of various patterned electrodes with feature sizes as small as 1–2 μm. The LED lithography offers a useful approach for cost-effective mild lithography without any costly instruments, high vacuum, or complex operation.

DOI： 10.1038/s41598-023-29281-w

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その他リンク： https://www.nature.com/articles/s41598-023-29281-w

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

We demonstrated a rational approach for designing highperformance polymer-based energy storage capacitors. Twodimensional paraelectric Ca2Nb3O10 nanosheets were deposited on a ferroelectric poly(vinylidene fluoride) (PVDF) film to form paraelectric/ferroelectric hetero-assemblies. Such an artificial structuring enabled tailoring of the breakdown strength and dielectric response, realizing an enhanced energy density (∼10 J cm-3) compared to pristine PVDF film (∼1 J cm-3).

DOI： 10.1246/cl.220466

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nanoscale  

The assembly of the surfactants has been utilized as unique templates for the controlled synthesis of metal nanosheets. However, current strategies for metal nanosheets have mainly focused on the liquid-phase surfactant assembly. Herein, we found the solid-state surfactants as designable crystals suitable for nanostructural control and proposed a novel synthetic route for molecularly thin Pt metal nanosheets using solid surfactant crystals as a precursor. The 2D surfactant crystals containing planarly arranged Pt complexes were prepared, and the subsequent UV-ozone treatment and reduction process allowed us to obtain Pt metal nanosheets. Pt metal nanosheets had a distinct morphology with various thicknesses (from 1.5 nm to 3.0 nm), characteristic of 2D surfactant crystals.

DOI： 10.1039/d2nr01807a

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Sustainable Energy and Fuels  

In this study, the photocatalytic activity of small particles of BiVO<inf>4</inf> for O<inf>2</inf> evolution using Fe³⁺ as an electron acceptor was investigated. Characterization by X-ray diffraction and electron microscopy revealed that small particles of BiVO<inf>4</inf> with 20-50 nm of sizes were obtained from micron-sized monoclinic scheelite-type BiVO<inf>4</inf> without changes in the crystal structure by ball milling treatment. The specific surface area increased from 0.7 to 22.6 m² g⁻¹ by the milling treatment. Although the milling treatment decreased the photocatalytic activity, the successive annealing treatment at 400 °C remarkably improved the activity of milled BiVO<inf>4</inf>. As a result, the annealed small particles of BiVO<inf>4</inf> achieved a slightly higher external quantum yield than the pristine one, 22.6% versus 20.8%. In contrast, the activity of non-milled BiVO<inf>4</inf> decreased due to the annealing treatment. Transient absorption spectroscopy using femtosecond and nanosecond pump lasers clarified the influences of the ball milling and annealing treatment on the carrier dynamics of BiVO<inf>4</inf>. The ball milling treatment accelerated recombination in picosecond and microsecond regions. For example, only 40% of photogenerated holes survived in milled BiVO<inf>4</inf> at 10 ps whereas 60% of holes remained in the non-milled sample. Annealing treatment at 400 °C suppressed the recombination in milled BiVO<inf>4</inf> but facilitated the recombination in the non-milled sample. The small BiVO<inf>4</inf> particles annealed at 400 °C, which exhibited high activity in sacrificial O<inf>2</inf> evolution, also showed high performance in overall water splitting by Z-scheme systems combined with Ru/SrTiO<inf>3</inf>:Rh of a H<inf>2</inf>-evolving photocatalyst. A small amount of annealed small BiVO<inf>4</inf> particles (5 mg) showed comparable activity in Z-scheme water splitting to the reaction with 30 mg of non-milled sample. In addition, in the Z-scheme water splitting based on interparticle electron transfer, the annealed small BiVO<inf>4</inf> allowed 17% higher activity than the non-milled sample.

DOI： 10.1039/d2se00065b

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

We present a method for synthesizing brookite-type titanium dioxide (TiO2) using an emulsion-assisted hydrothermal approach and a water-soluble titanium complex with glycolic acid as a complexing agent. In this study, stirred hydrothermal synthesis was used to synthesize water-in-oil emulsions with titanium glycolate complex in the aqueous phase. The resulting brookite-type TiO2 was investigated using Raman spectroscopy for crystal polymorph identification, X-ray Diffraction to identify crystal polymorphs and crystallite size, Transmission Electron Microscope for primary particle size, and crystal shape, and Dynamic Light Scattering for TiO2 secondary particle size in aqueous dispersion. The synthesized brookite-type TiO2 was a needle-like crystal with a width between 20 and 30nm and a length of more than 70 nm, growing in the b-axis direction at an angle of about 70?from the (120) plane. Furthermore, compared to the conventional synthesis method, the secondary particle size was smaller, and the dispersibility in water was improved. The results show that the brookite-type TiO2 dispersion obtained using the emulsion-assisted hydrothermal method can facilitate the formation of uniform films and can be applied to the electron transport layer of organic perovskite solar cells.

DOI： 10.2109/jcersj2.21127

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DOI： 10.2109/jcersj2.21003

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inorganic Chemistry  

NaMoO3F and Na5W3O9F5 were synthesized by solvothermal reaction of MoO3 and WO3, respectively, with NaF in nonaqueous solvents. These reactions were realized at low temperatures (150-200 °C) without the use of HF. This synthesis method is much more facile and safe procedure compared with general synthesis methods for oxyfluorides which includes hydrothermal reaction under a presence of HF or solid-state reaction at high temperatures in vacuum sealed tube or under high pressure. In the case of the reaction of MoO3 with NaF, the kind of solvent largely affected the obtained morphologies of NaMoO3F. The morphology in the case of acetonitrile as a solvent was rodlike with a micrometer-scale size, while that in the case of ethanol was polyhedral with a size of several hundred nanometers. In addition, the solvothermal reaction of WO3 with NaF led to the formation of Na5W3O9F5. Also, the difference of solvents for the solvothermal reaction affected the obtained particle sizes. The effect of the solvents on the morphologies of the obtained oxyfluorides probably resulted from the difference of the solubility of NaF and the subsequent dissolution ratio of MoO3 or WO3 in the used solvents. Our synthesis method can expand the applicability of oxyfluorides by providing a new phase and/or unique morphology.

DOI： 10.1021/acs.inorgchem.0c01175

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Catalysis B Environmental  

Microspherical particles of Rh-doped SrTiO<inf>3</inf> (SrTiO<inf>3</inf>:Rh) having size of 1–2 μm were synthesized by a spray drying (SD) method employing a water-soluble ammonium trilactatotitanate. When the calcination temperature increased up to 1200 °C, primary particles grew significantly while the microspherical morphology of the secondary particles was kept. Dynamic light scattering analysis proved well-dispersive nature of the SD sample. Photocatalytic activities of SrTiO<inf>3</inf>:Rh synthesized by the SD method, solid state reaction (SSR), and a polymerizable complex (PC) method were evaluated for H<inf>2</inf> evolution using an electron donor such as methanol, Fe²⁺, or [Co(bpy)<inf>3</inf>]²⁺ and Z-scheme water splitting combined with BiVO<inf>4</inf> of an O<inf>2</inf>-evolving photocatalyst and either Fe^3+/2+, [Co(bpy)<inf>3</inf>]^3+/2+, or reduced graphene oxide as an electron mediator. SrTiO<inf>3</inf>:Rh prepared by the SD method showed much higher activities for all Z-scheme water splitting than the samples synthesized by the SSR method. Activities of the SD sample for Z-scheme water splitting using electron shuttles, Fe^3+/2+ and [Co(bpy)<inf>3</inf>]^3+/2+, were slightly higher or comparable to those of the PC sample whereas the SD sample achieved higher activity in Z-scheme water splitting based on interparticle electron transfer. In addition, even when the mass of SrTiO<inf>3</inf>:Rh used for the Z-scheme system with Fe^3+/2+ was decreased from 50 mg to 30 mg, the SD sample still showed high activity while the activity decreased for the SSR and PC samples. Thus, usefulness of the SD method to obtain highly active SrTiO<inf>3</inf>:Rh with well-dispersive nature has been demonstrated.

DOI： 10.1016/j.apcatb.2019.04.009

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Omega  

Control over TiO<inf>2</inf> rutile crystal growth and morphology using additives is essential for the development of functional materials. Computer simulation studies on the thermodynamically stable conformations of additives at the surfaces of rutile crystals contribute to understanding the mechanisms underlying this control. In this study, a metadynamics method was combined with molecular dynamics simulations to investigate the thermodynamically stable conformations of glycolate, lactate, and 2-hydroxybutyrate ions at the {001} and {110} planes of rutile crystals. Two simple atom-atom distances were selected as collective variables for the metadynamics method. At the {001} plane, a conformation in which the COO^- group was oriented toward the surface was found to be the most stable for the lactate and 2-hydroxybutyrate ions, whereas a conformation in which the COO^- group was oriented toward water was the most stable for the glycolate ion. At the {110} plane, a conformation in which the COO^- group was oriented toward the surface was the most stable for all three hydroxylate ions, and a second most stable conformation was also observed for the lactate ion at positions close to the {110} plane. For all three hydroxylate ions (α-hydroxycarboxylate ions), the stability of the most stable conformation was higher for the {110} plane than for the {001} plane. At both planes, the stability of the most stable conformation was highest for the 2-hydroxybutyrate ion and lowest for the glycolate ion. Supposing that all three hydroxylate ions serve to decrease the surface free energy at the rutile surface and that a more stable conformation at the rutile surface leads to a greater decrease in the surface free energy, the present results partially explain experimentally observed differences in the changes in growth rate and morphology of rutile crystals in the presence of glycolic, lactic, and 2-hydroxybutyric acids.

DOI： 10.1021/acsomega.9b01100

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Bulletin of the Chemical Society of Japan  

Tantalum/nitrogen codoped titanium dioxide (TiO<inf>2</inf>:Ta,N) having a rutile structure has recently been reported to be a good photocatalyst for visible-light water oxidation. In this work, three different polymorphs of TiO<inf>2</inf>:Ta,N (anatase, brookite and rutile) were synthesized by a hydrothermal method using water-soluble titanium/tantalum complexes as precursors, followed by thermal nitridation with dry ammonia gas. Effects of the physicochemical properties on photocatalytic activity for O<inf>2</inf> evolution from an aqueous silver nitrate solution under visible light ( > 400 nm) were investigated. Experimental results indicated that defect formation during the nitridation procedure was the dominant factor for photocatalytic activity. Anatase TiO<inf>2</inf>:Ta,N was the most active for O<inf>2</inf> evolution among the three polymorphs, and also served as an O<inf>2</inf> evolution photocatalyst in Z-scheme overall water splitting in combination with Rh-doped strontium titanate (SrTiO<inf>3</inf>:Rh) and an Fe³⁺/ Fe²⁺ redox-shuttle mediator.

DOI： 10.1246/bcsj.20190037

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Solid State Chemistry  

Cation substitution for inorganic solid materials is a practical approach to control their functions. Here, synthesis, structure analysis, density functional theory (DFT) calculation of novel oxynitrides Ba<inf>1−x</inf>Sr<inf>x</inf>YSi<inf>2</inf>O<inf>5</inf>N, and investigation of their photoluminescence properties with Eu²⁺- or Ce³⁺-activator were conducted. Single crystal and powder X-ray analyses revealed that Ba<inf>1−x</inf>Sr<inf>x</inf>YSi<inf>2</inf>O<inf>5</inf>N were formed at x ≤ 0.75 and they were isotypic while the synthesis of SrYSi<inf>2</inf>O<inf>5</inf>N (x = 1) was not achieved by any synthesis conditions examined. Based on phonon calculation, it was concluded that the synthesis of SrYSi<inf>2</inf>O<inf>5</inf>N with the isostructure to BaYSi<inf>2</inf>O<inf>5</inf>N was impossible due to the thermodynamical unstability. Substitution of Ba with Sr decreased the average bond length of AE-(O,N) (AE = Ba and Sr) and increased distortion of AE sites. On the other hand, coordination environments of Y sites were rarely affected by the substitution. As a result, redshift and broadening of emission spectra for Eu-doped samples were observed, whereas there was almost no spectral change in Ce-doped samples.

DOI： 10.1016/j.jssc.2019.05.012

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Acta Crystallographica Section E Crystallographic Communications  

Single crystals of the solid solution series Ca 4+x Y 3-x Si 7 O 15+x N 5-x were obtained by a solid-state reaction method using a flux for x = 0, 0.5 and 1, resulting in Ca 4 Y 3 Si 7 O 15 N 5 (tetracalcium triyttrium heptasilicon oxynitride), Ca 4.5 Y 2.5 Si 7 O 15.5 N 4.5 and Ca 5 Y 2 Si 7 O 16 N 4 (pentacalcium diyttrium heptasilicon oxynitride). Single-crystal X-ray analysis revealed that the three compounds are isotypic and belong to space-group type P6 3 /m. Ca 2+ and Y 3+ cations are distributed over two crystallographic sites (site symmetry.. and 1) in a disordered manner. The corresponding (Ca,Y)-centred polyhedra are connected by edge-sharing, resulting in the formation of a layer structure extending parallel to (001). Three [Si(O,N)] 4 tetrahedra (two with point group symmetry m.., one with 3.. and half-occupancy) are condensed into an isolated [Si 7 (O,N) 19 ] unit, in which an [Si(O,N)] 4 tetrahedron is located at the center of a 12-membered oxynitride ring with composition [Si 6 O 15 N 3 ]. The present compounds are the first to have such an [Si 7 (O,N) 19 ] unit in their structures.

DOI： 10.1107/S2056989019001257

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Ceramics  

The functional properties of materials depend strongly on their morphologies. Here, the hydrothermal synthesis of rutile-type titania crystals with pseudocubic shapes using a water-soluble titanium complex is reported. This approach does not require extra additives or doping. Transmission electron microscopy and selected-area electron diffraction analysis revealed that they exposed high-index facets, such as {121}, and high-energy facets, such as {001}, which do not usually appear in rutile crystal. In terms of the formation of steps and kinks on pseudocubic rutile and coexisting anatase and brookite nanoparticles, the adsorption of nanoparticles might inhibit crystal growth, resulting in the formation of crystals with uncommon shapes exposing high-index and high-energy facets.

DOI： 10.3390/ceramics2010005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nanoscale  

A mixed valence compound, sodium titanium oxide bronze (Na <inf>x</inf> TiO <inf>2</inf> -B), combines intriguing properties of high electric conductivity and good chemical stability together with a unique one-dimensional tunnel crystal structure available for cation storage. However, this compound has not been studied for a long period because of the strongly reductive condition at high temperature required for its preparation, which limits the morphological control such as the preparation of nanocrystals. For the first time in this paper, the topotactic synthesis of nano-sized Na <inf>x</inf> TiO <inf>2</inf> -B with high specific surface area (>130 m ² g ^-1 ) from TiO <inf>2</inf> (B) nanoparticles has been demonstrated. The reaction of metastable TiO <inf>2</inf> (B) with NaBH <inf>4</inf> allows carrier electrons to be doped simultaneously with incorporation of Na ⁺ ions into the interstitial sites of the host Ti-O lattice at relatively low temperature. An electrochemical investigation of Li ⁺ - and Na ⁺ -ion storage behaviors suggests that the incorporated Na ⁺ ions are mainly placed in the 6-fold coordination sites of bronze. In addition, optical measurements including time-resolved transient spectroscopy revealed that the doped electrons in the Na <inf>x</inf> TiO <inf>2</inf> -B nanoparticles are predominantly in the Ti ³⁺ state and behave as a small polaron. The pelletized Na <inf>x</inf> TiO <inf>2</inf> -B nanoparticles shows a good electronic conductivity of 1.4 × 10 ^-2 S cm ^-1 at 30 °C with an activation energy of 0.17 eV, which is attributable to the thermal barrier for the polaron hopping.

DOI： 10.1039/c8nr08372j

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Photopolymer Science and Technology  

B-site-ordered double-perovskite oxide up-conversion phosphors La<inf>2</inf>ZnTiO<inf>6</inf>, La<inf>2</inf>MgTiO<inf>6</inf>, and Ba<inf>2</inf>LaTaO<inf>6</inf> doped with Yb and Ho, Er, or Tm were synthesized by a citric acid complex gelation method and a polymerizable complex method. Under 980-nm excitation, the double-perovskite oxide phosphors doped with luminescent ions at the A-site (La<inf>2</inf>ZnTiO<inf>6</inf> and La<inf>2</inf>MgTiO<inf>6</inf>) showed stronger up-conversion emission than the phosphor doped with luminescent ions at the B-site (Ba<inf>2</inf>LaTaO<inf>6</inf>). La<inf>2</inf>ZnTiO<inf>6</inf> and La<inf>2</inf>MgTiO<inf>6</inf>, in which dopants occupied the A-site, showed different up-conversion emission behaviors because of structural distortion resulting from the substitution of B-site cations.

DOI： 10.2494/photopolymer.32.593

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inorganic Chemistry  

Ce ⁴⁺ -based charge transfer phosphor is not common and has been reported mainly in Sr <inf>2</inf> CeO <inf>4</inf> with an excitation band peaking at ∼290 nm, mismatching with the near-ultraviolet light emitting diodes. Herein, we report a new series of Ce ⁴⁺ -based compounds Sr <inf>4.4</inf> Ce <inf>2.6</inf> REZnO <inf>12</inf> (RE = Y, La, and Eu) capable of photoluminescence induced by O ^2- -Ce ⁴⁺ charge transfer excitation under near-ultraviolet-visible light. The crystal structure of Sr <inf>4.4</inf> Ce <inf>2.6</inf> EuZnO <inf>12</inf> was determined by single crystal X-ray diffraction. The RE = La and Y samples were confirmed to be iso-structure compounds of the RE = Eu sample by powder X-ray diffraction. By introducing highly covalent Zn ²⁺ -O ^2- bonds into the framework, the Ce ⁴⁺ -O ^2- bonds are lengthened due to the effect of the Ce ⁴⁺ -O ^2- -Zn ²⁺ stretch. The lengthened Ce ⁴⁺ -O ^2- bond weakens the repulsion of the electrons between Ce ⁴⁺ and O ^2- , thereby lowering the charge transfer energy to the visible light region. Incorporation of Eu ³⁺ into the present compounds realized red emission under near-ultraviolet-visible excitation by the O ^2- -Ce ⁴⁺ charge transfer followed by energy transfer to Eu ³⁺ .

DOI： 10.1021/acs.inorgchem.8b01900

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Rsc Advances  

Doping of Cr⁶⁺ into BiVO<inf>4</inf> was examined in this study. A new absorption band with a 1.84 eV energy threshold appeared with Cr-doping. The theoretical band calculation has revealed that the new absorption is ascribed to the electron transition from the valence band to acceptor levels formed by empty Cr 3d orbitals. It was confirmed that photocatalytic water oxidation in the presence of Ag⁺ or Fe³⁺ of an oxidizing reagent was induced by excitation of the new absorption although activity under band gap excitation decreased with Cr-doping. Characteristics of carrier dynamics were also investigated by transient absorption spectroscopy.

DOI： 10.1039/C8RA07830K

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/fchem.2018.00467

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.180620

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.180605

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.snb.2018.08.021

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Handbook of Sol Gel Science and Technology Processing Characterization and Applications  

Silicon and phosphorous are important elements in materials science. There are less proper raw materials for synthesis of their compounds by aqueous solution- based sol-gel methods, because the conventional raw materials have low stability in aqueous conditions and/or high reactivity with other elements such as metal ions. In this chapter, preparation, chemistry, property, and stability of glycol-modified silanes (GMSs) and glycol-conjugated phosphate esters are summarized. The former is dispersed in an aqueous solution as silicon clusters, and the latter is dissolved in water. In addition, their applications for synthesis of silicates and phosphates by aqueous solution-based sol-gel methods are also documented using examples. The materials obtained showed high performance and phase purity caused by homogeneity of constituents at the atomic level. It is also clearly showed that introduction of such unconventional raw materials enables us to develop new compounds and new synthetic routes for synthesizing high-performance materials.

DOI： 10.1007/978-3-319-32101-1_135

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担当区分：筆頭著者   記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Powders of REMO<inf>4</inf> (RE: rare earth, M: Nb and Ta) were synthesized by a coprecipitation method employing watersoluble peroxo Nb/Ta complexes. This peroxo-based method is an aqueous solution route free from organics and halides. REMO<inf>4</inf> was directly crystallized by annealing the precursor under moderate conditions. It has been revealed that the precursors are also useful for synthesis of oxynitrides under mild nitriding conditions.

DOI： 10.1246/cl.170652

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Asian Ceramic Societies  

Control of crystal growth leads to highly functional materials with desired morphologies. In this study, the relationship between select additives and the crystal growth of rutile-type titania under hydrothermal conditions using α-hydroxy acids, carboxylic acids, or alcohols as additives was systematically investigated. Without additives, rod-like rutile crystals with average dimensions of 295 nm × 67 nm were formed. Acceleration of the crystal growth was observed and the aspect ratios of the resulting rod-like crystals were found to increase in the presence of the additives. Alcohols promoted crystal growth along the c-axis, but not in the direction to perpendicular to [001]. Carboxylic acids accelerated the overall crystal growth and this increase was more enhanced along the c-axis than that along others. Both effects were observed using α-hydroxy acids. In addition, the present results implied that the size of the hydrocarbon groups in alcohols and α-hydroxy acids appeared to be related to the acceleration of crystal growth along the c-axis. Hydroxy groups may reduce the surface energy of the crystal facets perpendicular to the c-axis by their adsorption on those facets, resulting in the formation of rod-like crystals with high aspect ratio.

DOI： 10.1016/j.jascer.2017.06.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Crystengcomm  

Crystalline mesoporous materials with oriented configurations are promising for high-performance energy storage and conversion devices. In this work, hierarchical microspheres constructed from radially oriented single-crystalline TiO<inf>2</inf> nanorods have been fabricated by a facile hydrothermal approach using oxalic acid as a chelating and structure-directing agent. The obtained mesoporous TiO<inf>2</inf> microspheres have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller specific surface area measurement to reveal their unique properties. The growth and assembly process of the nanorod-based microspheres were elucidated in view of chelation-assisted assembly. It was found that oxalic acid played a crucial role in the oriented assembly of nanorods into well-defined microspheres.

DOI： 10.1039/c7ce01158j

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

Tetravalent manganese is known as one of the candidate luminous centers to obtain red emission. There are still unclear factors in Mn⁴⁺-activated oxide phosphors to achieve intense emission. In this paper, we studied the photoluminescence properties of double perovskite-type tantalates AE<inf>2</inf>LaTaO<inf>6</inf> (AE = Ca, Sr, and Ba) activated with Mn⁴⁺. All AE<inf>2</inf>LaTaO<inf>6</inf>:Mn exhibited Mn⁴⁺-emission in the deep red region under excitation by near-ultraviolet-green light (300-570 nm) at room temperature. Co-substitution of Mg²⁺, Al³⁺, and Ti⁴⁺ compensates unbalanced charge caused by oxygen defects, resulting in the enhancement of Mn⁴⁺-emission. The present cosubstitution effect is different from the usual cosubstitution, such as the replacement of two Al³⁺ by Mn⁴⁺ and Mg²⁺, taking into consideration the charge balance between cations. Theoretical calculation of band structures based on density functional theory suggests the presence of two kinds of quenching schemes in AE<inf>2</inf>LaTaO<inf>6</inf>:Mn, photoionization and electron transfer from valence band to t<inf>2g</inf> orbitals of Mn.

DOI： 10.1021/acs.jpcc.7b06280

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担当区分：筆頭著者   記述言語：日本語  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Catalysis B Environmental  

Synthesis of a series of oxynitride Ba<inf>3-x</inf>La<inf>x</inf>Ta<inf>5</inf>O<inf>14−x</inf>N<inf>1+x</inf>(x = 0–1.5) with a tetragonal tungsten bronze (TTB) structure was examined using moist-NH<inf>3</inf>and 5% NH<inf>3</inf>-N<inf>2</inf>as nitriding atmosphere. The samples with x = 0–1 were successfully obtained as phase pure TTB oxynitride whereas the x = 1.5 samples gave a mixture of TTB oxynitride, Ta<inf>3</inf>N<inf>5</inf>, and LaTaO<inf>4</inf>. Absorption of TTB oxynitrides in visible region was enhanced as increasing the content of nitrogen. TTB oxynitrides exhibited both of H<inf>2</inf>and O<inf>2</inf>evolution under visible light in the presence of methanol and silver ions, respectively, as sacrificial reagents. Nitrogen poor surface in the samples synthesized under moist-NH<inf>3</inf>atmosphere was modified by annealing treatment using 5% NH<inf>3</inf>, resulting in improvement of photocatalytic activity for H<inf>2</inf>evolution. Evaluation using monochromatic light revealed that the apparent quantum efficiency of Ba<inf>2</inf>LaTa<inf>5</inf>O<inf>13</inf>N<inf>2</inf>was higher than that of Ba<inf>3</inf>Ta<inf>5</inf>O<inf>14</inf>N.

DOI： 10.1016/j.apcatb.2017.01.057

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

A novel oxynitride, BaYSi<inf>2</inf>O<inf>5</inf>N, has been synthesized by a solid-state reaction method. Its crystal structure was determined by single-crystal X-ray analysis. Eu²⁺- and Ce³⁺-doped BaYSi<inf>2</inf>O<inf>5</inf>N exhibit broad blue emission with peaks around 459 and 412 nm under excitation at 250-450 and 250-370 nm, respectively. This is the first report on the synthesis of oxynitrides in the BaO-Y<inf>2</inf>O<inf>3</inf>-SiO<inf>2</inf>-Si<inf>3</inf>N<inf>4</inf> system.

DOI： 10.1246/cl.170144

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry C  

In this work, novel single-phase white emitting Ca<inf>3</inf>Ln(AlO)<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>:Ce³⁺,Tb³⁺,Mn²⁺ (Ln = Y and Gd) phosphors were synthesized by a conventional solid-state reaction method. The crystal structure and photoluminescence properties were investigated for the first time. The structure of Ca<inf>3</inf>Ln(AlO)<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf> was formed by AlO<inf>6</inf> octahedral chains interconnected by BO<inf>3</inf> triangles. Along the [001] direction, the Ca/Ln cations fill in the trigonal and hexagonal tunnels. For Ca<inf>3</inf>Ln(AlO)<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>:Ce³⁺ and Ca<inf>3</inf>Ln(AlO)<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>:Mn²⁺, large Ce³⁺ preferred to occupy the smaller coordination site, while small Mn²⁺ occupied the larger coordination site, which was explained by the space hindrance. Due to the cation disorder, the local environment of Ce³⁺ was complicated and the emission band was extremely broad. In Ca<inf>3</inf>Ln(AlO)<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>, the emission color can be tuned from blue to green or red by tuning the Ce³⁺-Tb³⁺ or Ce³⁺-Mn²⁺ concentration based on energy transfer. Thus, the combination of blue, green and red emitting Ce³⁺, Tb³⁺ and Mn²⁺ generated white emission.

DOI： 10.1039/c7tc00941k

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記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Titanium Dioxide Nanoparticles Characterizations Properties and Syntheses  

Brookite is a polymorph of titania found in nature. Synthesis of single-phase brookite is difficult in comparison to anatase and rutile. It is well known that brookite has various potential applications. Therefore, methods for the synthesis of brookite with high purity are highly desirable. This chapter summarizes simple hydrothermal methods for the synthesis of brookite crystals with various morphologies using water-soluble titaniumcomplexes. Physical properties of the brookite powders obtained are also described. In addition, the formation mechanisms are discussed. A series of studies have indicated that the structures and nature of the complexes have a strong influence on the formation of brookite nuclei. Therefore, the titanium source is quite important for the selective synthesis of titania polymorphs. Application of the present approach allows the synthesis of rod-like brookite crystals with aspect ratios of 1 - 10, as well as snowflake-like crystal agglomerations. The mechanism of morphological control is also discussed.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Photopolymer Science and Technology  

Er³⁺/Yb³⁺ co-doped calcium tantalate up-conversion (UC) phosphors were synthesized via a parallel synthesis scheme using the gelable citrate complex method. Samples with various Ca/Ta atomic ratios were prepared, and their UC emission properties were compared. Under 980-nm near-infrared laser excitation, α-Ca<inf>2</inf>Ta<inf>2</inf>O<inf>7</inf>: Er³⁺, Yb³⁺ showed an extremely weak UC emission intensity and CaTa<inf>4</inf>O<inf>11</inf>: Er³⁺, Yb³⁺ demonstrated an excellent UC emission intensity. In addition, the local symmetry around the rare-earth dopant ions affected the UC luminescence properties.

DOI： 10.2494/photopolymer.30.507

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記述言語：日本語  

担当区分：筆頭著者   記述言語：英語  

DOI： 10.2109/jcersj2.16117

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Upconversion (UC) phosphors comprising Er³⁺/Yb³⁺ codoped rare-earth complex oxides, RE<inf>x</inf>Ta<inf>y</inf>O<inf>z</inf> and RE<inf>x</inf>Nb<inf>y</inf>O<inf>z</inf> (RE = Y, La, or Gd), were synthesized via the gelable citrate complex method, and their UC emission properties were compared. This led to the discovery of an intense green-emitting UC phosphor, YTa<inf>7</inf>O<inf>19</inf>:Er³⁺/Yb³⁺, which is the first example of a YTa<inf>7</inf>O<inf>19</inf> UC phosphor host material. Green UC emission obtained using optimum Er³⁺ and Yb³⁺ content was 20 times stronger than that obtained using a Y<inf>2</inf>O<inf>3</inf> host.

DOI： 10.1246/cl.160413

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Phosphors with sufficient red emission component are necessary for warm white light-emitting diodes. In this work on (Sr,Ba)<inf>2(1-x)</inf>Eu<inf>2x</inf>SiO<inf>4</inf> phosphors, (Sr,Ba)<inf>1.5</inf>Eu<inf>0.5</inf>SiO<inf>4</inf> achieved 75% of an internal quantum efficiency under excitation by blue light. Surprisingly, the (Sr,Ba)<inf>1.5</inf>Eu<inf>0.5</inf>SiO<inf>4</inf> exhibited orange emission, against the well-known traditional green-yellow emission of (Sr,Ba)<inf>2</inf>SiO<inf>4</inf>:Eu²⁺. Moreover, the concentration quenching of Eu²⁺ in (Sr,Ba)<inf>2</inf>SiO<inf>4</inf> was abnormally unobvious. With the help of calculations based on the density functional theory, it was discovered that the distinct local environment of luminescence centers rather than usual explanation such as self-absorption or intensified crystal field splitting, is responsible to the interesting red shifts in excitation and emission spectra. The refinement analysis based on X-ray diffraction revealed that the unequal distribution of Eu²⁺ to two crystallographic sites caused low concentration of Eu²⁺ at the 9-coordination site, inhibiting the concentration quenching. The (Sr,Ba)<inf>1.5</inf>Eu<inf>0.5</inf>SiO<inf>4</inf> phosphor has warmer emission than the commercial Y<inf>3</inf>Al<inf>5</inf>O<inf>12</inf>:Ce³⁺. This study also promotes research on the effect of site occupancy and the local environment of luminescence centers.

DOI： 10.1021/acsami.6b02237

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

A molecular dynamics simulation was conducted to elucidate the conformation and dynamics of a glycolate ion (CH<inf>2</inf>(OH)COO^-) at the surface of a TiO<inf>2</inf> rutile crystal. The simulation was performed for the {001} and {110} planes of the crystal. The results indicate that, for both planes, the conformation and dynamics of the ion are strongly dominated by a layered structure of water on the surface. The simulation suggests that the ion binds to the surface more stably on the {110} plane than on the {001} plane, and that the stable conformation of the ion at the surface differs between the planes: on the {110} plane the carboxyl group of the ion is preferentially oriented toward the surface, whereas on the {001} plane it is oriented toward liquid water. These simulation results are compared with the growth shapes of rutile crystals synthesized in the presence of glycolic acid, and the role of glycolate ions in controlling the morphology of rutile crystals is discussed. (Figure Presented).

DOI： 10.1021/acs.jpcc.5b11087

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Calcium silicate cosubstituted with Sr²⁺ and Eu²⁺ was studied in order to examine the relationship between emission characteristics and Eu²⁺ occupancy at two types of Ca sites (Ca(1n) and Ca(2n)). The results clearly indicate that red emission of the Ca2<inf>2</inf>-SiO<inf>4</inf>:Eu²⁺ phosphor is caused by Eu²⁺ substitution at the Ca(2n) site. In addition, red shift in emission of Eu(2n) occurs when large amounts of Eu were substituted.

DOI： 10.1246/cl.151145

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Research  

Although there are numerous reports on the synthesis of spherical materials, the development of new approaches remains important for theory construction to realize tailor-made synthesis of spherical materials. Herein, we report the synthesis of polydispersed spherical particles of H2Ti2O5 intercalated with a polyethyleneamine, such as an ethylenediamine, on the basis of a solvothermal treatment using concentrated polyethyleneamine aqueous solutions. The diameter of the micrometer-sized spheres enlarged with increasing amine concentration in the reaction solution. It was speculated that high ionic strength caused the self-assembly of polyethyleneamine-intercalated H2Ti2O5, resulting in the formation of spherical agglomerates. The spheres had a specific a surface area of 200 m² g^-1 and approximately 5 nm pores, and these values were controlled by amine concentration and treatment time. Conversion to single phase anatase and rutile without changes in spherical morphology was achieved by heat treatment. The present approach may assist with the design morphology of agglomerates.

DOI： 10.1557/jmr.2016.67

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本結晶成長学会  

Control of crystal growth is rather important in the field of materials, because the shape directly affects their functional abilities. Our research group engages in hydrothermal synthesis of titanium dioxide, which is regarded as one of the representative ceramics, using water-soluble titanium complexes. The high chemical stability and peculiar molecule structures of these titanium complexes allowed us to use various compounds which play a role in control of crystal growth, resulting in the selective synthesis of four titanium dioxide polymorphs, that is, rutile, anatase, brookite and TiO_2(B), with a controlled shape. This paper summarizes our past study and reported researches on synthesis of titania polymorph crystals by classification of zero-, one-, two-, and three-dimensional structures.

DOI： 10.19009/jjacg.42.4_283

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.16117

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Carbon  

Graphene/M<inf>x</inf>WO<inf>3</inf> (M = Na, K) nanocomposites with different weight ratios were successfully synthesized using MBH<inf>4</inf> as a reducing agent in aqueous solution, followed by crystallization of amorphous precursors under calcination in H<inf>2</inf> (5 vol.%)/N<inf>2</inf> atmosphere at 600 °C. The coupled samples showed good shielding properties in NIR wavelength range together with certain visible lights transparency. The as-prepared tungsten bronze nanoparticles are homogeneously anchored on graphene sheets, and the graphene/tungsten bronze nanocomposite showed an enhanced electrical conductivity with good shielding properties in the NIR range together with certain visible lights transparency. With the increment of graphene amount in the composites, the contact between the graphene sheets was enhanced, and the M<inf>x</inf>WO<inf>3</inf> might enhance the charge transport properties of graphene by generating the short conductive path for electrons over the remained oxygenated functional groups. The synergistic effects could be observed in the composites. When 5 wt.% or more graphene were composed into M<inf>x</inf>WO<inf>3</inf>, the hybrid composite showed the higher electrical conductivity than those of uncoupled graphene and tungsten bronze alone.

DOI： 10.1016/j.carbon.2015.06.072

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

8479

DOI： 10.4236/opj.2015.511031

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その他リンク： http://file.scirp.org/xml/61445.xml

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

It has been found that Mn⁴⁺-activated La<inf>2</inf>MTiO<inf>6</inf> (M = Mg and Zn) functions as novel Eu-free phosphors for red emission in this work. La<inf>2</inf>MTiO<inf>6</inf>:Mn⁴⁺ exhibited emission with a peak at 710 nm under excitation by ultraviolet to blue light (300-550 nm). La<inf>2</inf>MgTiO<inf>6</inf>:Mn⁴⁺ exhibited stronger emission than La<inf>2</inf>ZnTiO<inf>6</inf>:Mn⁴⁺. The internal quantum yield of La<inf>2</inf>MgTiO<inf>6</inf>:Mn⁴⁺ was 58.7% under the excitation at 330 nm.

DOI： 10.1246/cl.150748

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Nanoscience and Nanotechnology  

Reduced graphene oxide (rGO)/rod-shaped potassium tungsten bronze nanocomposites with the different ratio were successfully synthesized by solvothermal reaction and followed by the reduction in H<inf>2</inf>(5 vol.%)/N<inf>2</inf> atmosphere at 550 °C. The coupled samples showed excellent shielding ability of NIR light as well as certain visible lights transparency. The synergistic effects could be observed in the composites, i.e., when 15 wt% and 20 wt% of rGO which was fabricated by chemical reduction of graphene oxide, were composed into K<inf>x</inf>WO<inf>3</inf>, the composite showed the higher electrical conductivity than those of rGO and potassium tungsten bronze.

DOI： 10.1166/jnn.2015.10579

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

A novel picolinate-iron(III) compound, Fe(C<inf>6</inf>H<inf>4</inf>NO<inf>2</inf>)<inf>2</inf>(OH) (1), was synthesized from an aqueous solution of a picolinate-iron(II) complex. Compound 1 was obtained by a thermal treatment of the picolinate-iron complex aqueous solution, whose pH was adjusted to 37, containing more than twice molar picolinic acid (Hpa) to Fe at 353K for 72 h. When the iron aqueous solution in the presence of more than six times molar Hpa to Fe at pH 25 was heated, Fe(C<inf>6</inf>H<inf>4</inf>NO<inf>2</inf>)<inf>3</inf>-H<inf>2</inf>O (2) appeared. Millimeter-sized yellow-green single crystals of 2 could be obtained by the heat treatment of the picolinate-iron aqueous solution, whose pH was adjusted to 3, with Fe²⁺:Hpa = 1:10 at 373K for 72 h. Formation mechanism of 1 and 2 was also discussed through investigations of relationship between synthesis conditions and products. Our approach opens a promising new route for preparation of precursors for synthesis of high functional ceramics and development of new organicinorganic hybrids.

DOI： 10.2109/jcersj2.123.751

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Two novel pyrazine-2-carboxylate titanium complexes were synthesized from an aqueous solution (1) and 1 in N,Ndimethylformamide (DMF) (2). The structure of 2 was determined to be [Ti<inf>6</inf>O<inf>8</inf>(C<inf>4</inf>H<inf>3</inf>N<inf>2</inf> COO)<inf>8</inf>(C<inf>3</inf>H<inf>7</inf>NO)<inf>4</inf>]• 4C<inf>3</inf>H<inf>7</inf>NO• H<inf>2</inf>O by single-crystal X-ray analysis. Both complexes exhibited solvent adsorptiondesorption accompanying reversible structural change. 1 and 2 were compatible, and 1 was vital for the synthesis of 2. The degassed 1 showed gate adsorption property for water vapor.

DOI： 10.1246/cl.150393

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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DOI： 10.1246/cl.150341

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Crystal Growth  

Recently, shape-controlled synthesis of crystals exposing high-index facets has attracted much research interest due to their importance for both fundamental studies and technological applications. Herein, crystals of rutile-type TiO<inf>2</inf> with hierarchical structures exposing high-index facets have been synthesized by a facile hydrothermal method using water-soluble titanium complex as a precursor and picolinic acid as structure-directing and shape-controlling agents. The synthesized particles were composed of several branches of pyramidal crystals with relatively smooth surface. On the basis of investigation results, it was speculated that the mutual π-stacking and selective adsorption of picolinic acid on specific {111} facets resulted in the formation of rutile crystals bound by high-index surfaces such as {331}.

DOI： 10.1016/j.jcrysgro.2015.02.056

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Funtai Oyobi Fummatsu Yakin Journal of the Japan Society of Powder and Powder Metallurgy  

In this paper, we demonstrated the synthesis of silicate-based phosphors by solution techniques using glycolmodified silane (GMS) as a Si source. GMS is a water-dispersible inorganic Si cluster, which is vitally involatile and nonflammable compounds, compared to volatile and flammable Si-alkoxides such as tetraethoxysilane (TEOS). Therefore, GMS has allowed the silicon containing compounds to be synthesized through various solution processes for ceramic compounds such as polymerizable complex (PC) and amorphous metal complex (AMC) methods. This paper provides examples of synthesis of new silicate-based phosphors such as NaAlSiO<inf>4</inf>:Eu²⁺, BaZrSi<inf>3</inf>O<inf>9</inf>:Eu²⁺, and CaSrSiO<inf>4</inf>:Eu²⁺. In addition, other examples of improvement of emission for conventional silicate-based phosphors, Y<inf>2</inf>SiO<inf>5</inf>:Ce³⁺-Tb³⁺ and Zn2SiO<inf>4</inf>:Mn²⁺, prepared by the above solution techniques including homogeneous precipitation using GMS are also given in this paper.

DOI： 10.2497/jjspm.62.127

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Journal  

Nature produces materials with excellent physical and chemical properties using water as a medium under ambient temperature and pressure. The current need for more highly functional and compact materials makes the mimicking of natural processes to produce these materials a very interesting approach, not only to obtain highly functionalized materials but also to reduce the environmental impact. Our research group is engaged in the development of new stable water-soluble compounds that follow natural processes for the synthesis of materials using water as a medium. This paper summarizes a hydrothermal synthesis of rutile-type titanium oxide using water-soluble titanium complexes, controlling the crystal morphology by utilizing organic molecules as shape-control agents as well as their speculative formation mechanism and superior dielectric properties of unusually shaped titanium oxide crystals. By recapitulating our results, we indicate that control of the nano- and macro-structures and functional improvement are accomplished through the development of new precursor compounds.

DOI： 10.1038/pj.2014.89

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Dalton Transactions  

NaBa<inf>1-x</inf>Ca<inf>x</inf>PO<inf>4</inf>:Eu²⁺ were synthesized using polymerizable complex method. New phases were observed at x = 1/3 and 0.5, which were identified by single-crystal XRD analysis as Na<inf>3</inf>Ba<inf>2</inf>Ca(PO<inf>4</inf>)<inf>3</inf> and NaBa<inf>0.5</inf>Ca<inf>0.5</inf>PO<inf>4</inf> with a trigonal system. Though both phases pretend to be solid solutions between NaBaPO<inf>4</inf> and NaCaPO<inf>4</inf>, they have different coordination environments and PO<inf>4</inf> orderings. 1 mol% Eu²⁺-activated NaBaPO<inf>4</inf>, Na<inf>3</inf>Ba<inf>2</inf>Ca(PO<inf>4</inf>)<inf>3</inf>, and NaBa<inf>0.5</inf>Ca<inf>0.5</inf>PO<inf>4</inf> exhibited an emission maximum at 435 nm, 458 nm, and 460 nm, respectively. The shift of the emission maximum might be due to a change in the Eu-O bond length. This journal is

DOI： 10.1039/c4dt03024a

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Rsc Advances  

Controlled/living radical polymerization was examined with the use of magnetic iron oxide (Fe<inf>3</inf>O<inf>4</inf>) prepared through various processes, including hydrothermal synthesis, a bioinspired process, and magnetotactic bacteria. Prior to the use of various types of Fe<inf>3</inf>O<inf>4</inf>, commercially available Fe<inf>3</inf>O<inf>4</inf> was employed as a heterogeneous catalyst for styrene polymerization in conjunction with an alkyl halide as an initiator. Under appropriately optimized conditions, with the addition of Ph<inf>3</inf>P in a solvent mixture of toluene and DMF, the polymerization proceeded in a well-controlled manner. In addition, solid Fe<inf>3</inf>O<inf>4</inf> was recovered using a magnetic approach and was reused for a polymerization reaction. The effects of stirring on the polymerization rate suggest that the surface of Fe<inf>3</inf>O<inf>4</inf> is responsible for the catalysis in polymerization. Fe<inf>3</inf>O<inf>4</inf> samples prepared through various processes were then used for styrene polymerization and showed different activities depending on the preparation process. In particular, Fe<inf>3</inf>O<inf>4</inf> prepared through hydrothermal synthesis exhibited a much higher activity compared with commercial Fe<inf>3</inf>O<inf>4</inf>.

DOI： 10.1039/c5ra09149g

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

Single phase Zn<inf>1-2x</inf>(CuGa)<inf>x</inf>Ga<inf>2</inf>S<inf>4</inf> was successfully synthesized by a two-step route: synthesis of an oxide precursor by a polymerizable complex (PC) method followed by sulfurization under a H<inf>2</inf>S-Ar flow. The samples thus obtained were porous aggregates consisting of fine crystals with 50 nm size. Among the examined compositions, Zn<inf>0.4</inf>(CuGa)<inf>0.3</inf>Ga<inf>2</inf>S<inf>4</inf> (x = 0.3) showed the highest activity for H<inf>2</inf> evolution from an aqueous solution containing S^2- and SO<inf>3</inf>^2- as electron donors under visible light irradiation. The apparent quantum yield of the optimized sample with deposition of 2 wt% of Rh was 19% at 420 nm. This value is higher than that of the sample synthesized by a solid state reaction (15%). Therefore, improvement of the photocatalytic performance of Zn<inf>0.4</inf>(CuGa)<inf>0.3</inf>Ga<inf>2</inf>S<inf>4</inf> for H<inf>2</inf> evolution has been achieved by using the two-step synthesis method including the preparation of an oxide precursor by the PC method.

DOI： 10.1039/c5ta02114f

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

Solid solutions between LaTaON<inf>2</inf> and SrTiO<inf>3</inf> were successfully synthesized. In this solid solution, the valence band maxima (VBM) shifted to positive sides as the fraction of SrTiO<inf>3</inf> increased, resulting in the appearance of activity for O<inf>2</inf> evolution even without any cocatalysts. Despite widening of the band gap (E<inf>g</inf>) by only 0.15 eV, La<inf>0.5</inf>Sr<inf>0.5</inf>Ta<inf>0.5</inf>Ti<inf>0.5</inf>O<inf>2</inf>N gained 0.5 V larger driving force for water oxidation, which corresponds to the potential difference between VBM and potential for water oxidation, than LaTaON<inf>2</inf>. It suggested that the contribution of Ti 3d to the conduction band suppressed the widening of E<inf>g</inf>. This is an interesting feature in the present LaTaON<inf>2</inf>-SrTiO<inf>3</inf> solid solution. The bare La<inf>0.5</inf>Sr<inf>0.5</inf>Ta<inf>0.5</inf>Ti<inf>0.5</inf>O<inf>2</inf>N exhibited the activity for O<inf>2</inf> evolution 9 times higher than LaTaON<inf>2</inf> modified with a CoO<inf>x</inf> cocatalyst. It has been found that the driving force for water oxidation of La<inf>0.5</inf>Sr<inf>0.5</inf>Ta<inf>0.5</inf>Ti<inf>0.5</inf>O<inf>2</inf>N was 0.8 V, and was larger than those in other perovskite-type oxynitrides.

DOI： 10.1039/c5ta02482j

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.19009/jjacg.42.4_283

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2497/jjspm.62.127

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

A carbon modified NaTaO<inf>3</inf> mesocrystal nanoparticle (ca. 20 nm) was successfully synthesized by a one-pot solvothermal method, employing TaCl<inf>5</inf> and NaOH as the starting materials and distilled water/EG mixed solution as a reaction solvent in the presence of appropriate amounts of glucose. The mesocrystal sample presented a high specific surface area 90.8 m² g^-1 with large amounts of well-dispersed mesopores in the particle, owing to the co-effect of EG and glucose during the reaction process. A non-classic mechanism of formation was proposed for the growth of the NaTaO<inf>3</inf> mesocrystal. Furthermore, the NaTaO<inf>3</inf> mesocrystal exhibited considerably improved visible light absorption in addition to the intrinsic UV light absorption as a result of carbon modification originated from glucose. On the basis of the large specific surface area, high crystallinity and optical property, the carbon modified NaTaO<inf>3</inf> mesocrystal demonstrated excellent efficiency for continuous NO gas destruction under irradiation of UV, short wavelength visible lights (>400 m) and even long wavelength visible light (>510 nm), considerably superior to those of the unmodified NaTaO<inf>3</inf> specimen and commercial titania, P25. The carbon modified NaTaO<inf>3</inf> mesocrystal nanoparticles prepared in this work would probably have potential utilization in environmental purification and energy conversion.

DOI： 10.1039/c4ta04132a

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Luminescence  

Two novel Eu²⁺-activated phosphors in the Na-Sc-Si-O system were developed in this study, NaScSi<inf>2</inf>O<inf>6</inf>:Eu and Na <inf>3</inf>ScSi<inf>3</inf>O<inf>9</inf>:Eu. NaScSi<inf>2</inf>O <inf>6</inf>:Eu²⁺ showed yellow emission with a peak at 555 nm under excitation at 220-430 nm. When flux-treatment was performed for NaScSi <inf>2</inf>O<inf>6</inf>:Eu²⁺, we found the existence of a new phase. We then succeeded in synthesis of a high-purity sample of this new compound by a parallel solution synthesis method. It was revealed that the new phase was Na<inf>3</inf>ScSi<inf>3</inf>O<inf>9</inf> with isostructure to Na<inf>3</inf>YSi<inf>3</inf>O<inf>9</inf>, and Eu²⁺-activated Na<inf>3</inf>ScSi<inf>3</inf>O<inf>9</inf> exhibited photoluminescence. Na <inf>3</inf>ScSi<inf>3</inf>O<inf>9</inf>:Eu showed green emission with a peak at 530 nm and a corresponding broad excitation band up to 500 nm. However, photoluminescence of Eu²⁺ was negligible for Na<inf>3</inf>YSi <inf>3</inf>O<inf>9</inf>:Eu because of the stabilization of Eu³⁺ at the Y³⁺ site. © 2014 Elsevier B.V.

DOI： 10.1016/j.jlumin.2014.05.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

The synthesis of oxyfluoride solid solutions with the composition (Ca<inf>1-x</inf>Sr<inf>x</inf>)<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>is reported in this study. (Ca<inf>1-x</inf>Sr<inf>x</inf>)<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>is found to form a solid solution within the entire composition range. Synthesis of Sr<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>, which is the first compound in the SrSiOF system, can be regarded as one of the interesting results of this study. The Eu²⁺-activated (Ca<inf>1-x</inf>Sr<inf>x</inf>)<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>solid solutions, except for Sr<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>exhibited photoluminescence under excitation at 300450nm at room temperature. The samples with x = 0.250.75 showed a broad red emission band with a peak around 630 nm, whereas the Ca<inf>4</inf>Si<inf>2</inf>O<inf>7</inf>F<inf>2</inf>:Eu²⁺(x = 0) showed blue emission with a peak at 470 nm. Thus, the substitution of Sr for Ca in Ca<inf>4</inf>SiO<inf>7</inf>F<inf>2</inf>:Eu²⁺changed the photoluminescence properties remarkably.

DOI： 10.2109/jcersj2.122.630

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

The stability and reactivity of phosphate raw materials, including two water-soluble phosphates, ethylene glycol-conjugated phosphate (EG-P), and polyethylene glycol-conjugated phosphate (PEG-P) developed by our group, were examined with the aim of synthesizing phosphates with high functionalities. EG-P was found to gradually hydrolyze in an aqueous solution, resulting in the formation of H<inf>3</inf>PO<inf>4</inf>, while PEG-P was stable for more than two months. EG-P and PEG-P did not form insoluble materials in aqueous solution in the presence of many other cations, while precipitates were often observed using conventional phosphate raw materials. In particular, there were no precipitates in an aqueous solution of PEG-P in the presence of Ca2⁺and Li⁺ions, which easily formed insoluble phosphates in a given aqueous condition. Consequently, single-phase LiCaPO<inf>4</inf>with high luminescence properties could be obtained by a polymerizable complex method employing PEG-P, while impurity phases were formed using other P sources, and KSrPO<inf>4</inf>was formed as a single phase using EG-P and PEG-P.

DOI： 10.2109/jcersj2.122.626

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Angewandte Chemie International Edition  

We report a new dicalcium silicate phosphor, Ca<inf>2-x</inf>Eu <inf>x</inf>SiO<inf>4</inf>, which emits red light in response to blue-light excitation. When excited at 450 nm, deep-red emission at 650 nm was clearly observed in Ca<inf>1.2</inf>Eu<inf>0.8</inf>SiO<inf>4</inf>, the external and internal quantum efficiencies of which were 44 % and 50 %, respectively. The red emission from Ca<inf>2-x</inf>Eu<inf>x</inf>SiO<inf>4</inf> was strongly related to the peculiar coordination environments of Eu²⁺ in two types of Ca sites. The red-emitting Ca<inf>2</inf>SiO<inf>4</inf>:Eu ²⁺ phosphors are promising materials for next-generation, white-light-emitting diode applications. A dicalcium silicate phosphor, Ca <inf>2-x</inf>Eu<inf>x</inf>SiO<inf>4</inf>, emits red light in response to blue-light excitation. When excited at 450 nm, deep-red emission at 650 nm was clearly observed in Ca<inf>1.2</inf>Eu<inf>0.8</inf>SiO<inf>4</inf>. The picture shows a photograph of the corresponding Ca<inf>1.20</inf>Eu <inf>0.80</inf>SiO<inf>4</inf> phosphor upon excitation with blue LEDs. The external and internal quantum efficiencies were 44 % and 50 %, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/anie.201402520

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記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Research  

Novel water-soluble titanium complexes coordinated by hydroxycarboxylic acids or amines were developed, and the hydrothermal treatment of the new complexes was carried out to elucidate the formation mechanism of the titania polymorphs including rutile, anatase, and brookite. An empirical relationship among the crystal structure of TiO2, the ligand, and the complex structure was found. Anatase, rutile, or a mixture of both was obtained by the hydrothermal treatment of the complexes coordinated by hydroxycarboxylic acids. The structure of complexes prepared using hydroxycarboxylic acids, which have one hydroxyl and one carboxylic groups, seems to be preferable for the formation of rutile. It was also found that the hydrothermal treatment of titanium complexes coordinated by amine with NAc2 structure resulted in the formation of brookite. Thus, the effect of ligand and complex structure on the crystal structure of TiO2 synthesized by the hydrothermal treatment of the complexes was proposed. © Materials Research Society 2013.

DOI： 10.1557/jmr.2013.229

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Asian Ceramic Societies  

Hydrothermal synthesis of Fe <inf>3</inf> O <inf>4</inf> (magnetite) particles was carried out using organic compounds as morphology control agents to obtain magnetite crystals with uncommon facets. It was established that the morphology of Fe <inf>3</inf> O <inf>4</inf> crystals obtained by hydrothermal treatment of an aqueous solution containing Fe ²⁺ and organic compounds depended on the organic compound used. The shape of the Fe <inf>3</inf> O <inf>4</inf> particles obtained when no additives were used was quasi-octahedral. In contrast, the addition of picolinic acid, citric acid or pyridine resulted in the formation of polyhedral crystals, indicating the presence of not only {111}, {100} and {110} facets but also high-index facets including at least {311} and {331}. When citric acid was used as an additive, octahedral crystals with {111} facets also appeared, and their size decreased as the amount of citric acid was increased. Thus, control of Fe <inf>3</inf> O <inf>4</inf> particle morphology was achieved by a simple hydrothermal treatment using additives. © 2014 The Ceramic Society of Japan and the Korean Ceramic Society.

DOI： 10.1016/j.jascer.2014.05.008

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担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5772/57533

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7678

DOI： 10.4236/opj.2013.36A003

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7677

DOI： 10.4236/opj.2013.36A002

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7679

DOI： 10.4236/opj.2013.36A004

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7680

DOI： 10.4236/opj.2013.36A006

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7621

DOI： 10.2109/jcersj2.121.593

Open Access

記述言語：英語  

記述言語：英語  

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7618

DOI： 10.1246/cl.130216

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7774

DOI： 10.1007/s11164-012-0894-1

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担当区分：筆頭著者   記述言語：日本語  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

7466

DOI： 10.1039/c3ta10257b

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7617

DOI： 10.1039/c3cy00014a

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c3tc31121j

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7312

DOI： 10.1149/2.019302jss

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

7681

DOI： 10.1039/c3cy00557g

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

Morphological control as well as formation of nanoparticles of anatase-type titanium dioxide has been achieved by a solvothermal treatment of a water-soluble citratoperoxotitanium (CPT) complex using ethylenediamine (EDA) as a key solvent in the presence of a given amount of water. When the EDA concentration in the whole solvent (EDA + H₂O) remained low less than 12 M, the powder obtained after the solvothermal treatment consisted of spindle-like anatase particles. With an increase of the EDA concentration in the solvent, the shape of the obtained particles changed from spindle to square bipyramid. When another water-soluble oxoglycolatoperoxotitanate complex or TiCl₄ was used as a starting source of Ti, similar shaped anatase particles could be obtained by a careful choice of synthetic conditions. Using a mixed solvent of EDA and water, sheet-like titanic acid was produced as an intermediate phase, regardless of the EDA concentration. Therefore, the formation of anatase in the current system may take place through dissolution-recrystallization of titanic acid. The formation of square bipyramidal anatase particle achieved in the present study is not agreement with a reported theoretical calculation of equilibrium phase, because the calculation reveals that truncated square bipyramid-like anatase is obtained under an acidic condition and spindle-like anatase was formed under a basic condition. An adsorption of EDA on particle surface and the pH of the solvent may contribute to the achievement of morphological control.

DOI： 10.2109/jcersj2.120.494

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記述言語：英語  

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/ejic.201200421

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ic300049j

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jcrysgro.2011.09.046

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

Phase- and morphology-control of TiO₂ was performed by a facile hydrothermal method using a novel water-soluble titanium&ndash;picolinato complex as a precursor. Single-phase rutile or brookite type titania can be obtained by tailoring the pH of the complex solution. Rutile with a hierarchical microstructure was synthesized using an excess amount of ligand as an additive and the final product consisted of microspheres with mesopores formed by a self-assembly of nanorods. The anisotropic growth of nanorods with a high aspect ratio was explained by a capping mechanism.

DOI： 10.2109/jcersj2.119.513

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本化学会  

The growing significance of nanocrystalline inorganic functional materials in the fields of catalysis, electronics, and energy conversion together with the increasing demand of the society for safer, softer, and &ldquo;greener&rdquo; technologies has drawn considerable attention of the researchers toward water-based solution processes for synthesis of such materials. In this respect complex oxides, containing d⁰-transition metals, such as Ti, Nb, Ta, or Si represent an outstanding challenge for materials chemists due to the extremely narrow range or almost complete absence of suitable precursor compounds compatible with aqueous systems. In the recent 10 years, a remarkable progress has been achieved in the development of new water-soluble complexes of titanium and considerable experience was accumulated in the application of these compounds for synthesis of nanocrystalline titanium-containing materials. The essential knowledge of coordination chemistry of such water-soluble titanium complexes is reviewed in this work, which succeeded to identify the key structural features responsible for stability of the compounds against hydrolysis and to provide guidelines for synthesis of these complexes. Finally, an extensive overview of highly selective aqueous solution based synthesis of TiO₂ polymorphs as well as complex oxide materials with the help of the novel water-soluble titanium complexes is provided.

DOI： 10.1246/bcsj.20100103

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担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 粉体粉末冶金協会  

A panel of new stable and water soluble complexes of titanium (IV) with natural hydroxy-carboxylic acids such as citric, tartaric, lactic or glycolic acid as ligands was developed. A typical structure of these complex ions includes a peroxo-group, and a hydroxy-carboxylic acid molecule attached to the metal ion by carboxylic and hydroxylic groups to form stable species. The tight coordination and negative charge of complex ions are responsible for stability of these new compounds in water solutions in a wide range of temperatures and pH. Use of natural non-toxic ligands and ammonium as counterions make such titanium compounds convenient reagents for "green" synthesis of titanium containing materials by aqueous solution methods.<BR>The architecture of titanium complexes includes structural motifs of different polymorphic forms of TiO<SUB>2</SUB>, which allows for application of these compounds as building blocks (tecton) for synthesis of titania with different crystal structures by a simple hydrothermal processes. In this way anatase, rutile, TiO<SUB>2</SUB>(B) and brookite were prepared in a reproducible and highly selective way. For the first time TiO<SUB>2</SUB>(B) and brookite were synthesized as single phase nano-crystals by a "one-pot" hydrothermal process, and their outstanding photo-catalytic activities were revealed.

DOI： 10.2497/jjspm.56.188

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

DOI： 10.2109/jcersj2.117.320

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

The metastable phase of TiO_2(B), one of the polymorphs of titanium dioxide (TiO_2), was prepared by a hydrothermal treatment of a titanium glycolate complex ([Ti_4(C_2H_2O_3)_4(C_2H_3O_3)_2(O_2)_4O_2]^<6->) at 473K for 1-72h in the presence of H_2SO_4. Characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the obtained samples were composed of single phase TiO_2(B) and the particles had plate-like morphology. After post-synthetic hydrothermal crystal growth (PHCG) applied to the as-prepared sample, thicker plate-like shaped particles were obtained. The photocatalytic activities of the samples obtained by the hydrothermal treatment and after the subsequent PHCG were evaluated in terms of methanol decomposition.

DOI： 10.2109/jcersj2.117.347

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担当区分：筆頭著者   記述言語：日本語  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1551-2916.2008.02641.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jcrysgro.2008.09.041

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jcrysgro.2008.09.041

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1551-2916.2008.02641.x

Open Access

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

CiNii Research

記述言語：英語  

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1107/S0108767308099406

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10853-007-1912-3

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1007/s10853-007-2113-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

DOI： 10.2109/jcersj2.116.578

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CiNii Research

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1107/S0108767308099406

Open Access

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.115.826

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.115.835

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/cm071370q

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記述言語：日本語  

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.4028/www.scientific.net/SSP.124-126.723

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/anie.200503565

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PubMed

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担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：特定非営利活動法人 日本火山学会  

DOI： 10.18940/kazan.51.4_245

Open Access

CiNii Research

記述言語：日本語  

記述言語：日本語 著書種別：学術書

Silicon and phosphorous are important elements in materials science. There are less proper raw materials for synthesis of their compounds by aqueous solution- based sol-gel methods, because the conventional raw materials have low stability in aqueous conditions and/or high reactivity with other elements such as metal ions. In this chapter, preparation, chemistry, property, and stability of glycol-modified silanes (GMSs) and glycol-conjugated phosphate esters are summarized. The former is dispersed in an aqueous solution as silicon clusters, and the latter is dissolved in water. In addition, their applications for synthesis of silicates and phosphates by aqueous solution-based sol-gel methods are also documented using examples. The materials obtained showed high performance and phase purity caused by homogeneity of constituents at the atomic level. It is also clearly showed that introduction of such unconventional raw materials enables us to develop new compounds and new synthetic routes for synthesizing high-performance materials.

DOI： 10.1007/978-3-319-32101-1_135

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総ページ数：416   担当ページ：217-226   記述言語：日本語 著書種別：学術書

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担当ページ：71-92   記述言語：英語 著書種別：学術書

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記述言語：日本語 著書種別：学術書

Brookite is a polymorph of titania found in nature. Synthesis of single-phase brookite is difficult in comparison to anatase and rutile. It is well known that brookite has various potential applications. Therefore, methods for the synthesis of brookite with high purity are highly desirable. This chapter summarizes simple hydrothermal methods for the synthesis of brookite crystals with various morphologies using water-soluble titaniumcomplexes. Physical properties of the brookite powders obtained are also described. In addition, the formation mechanisms are discussed. A series of studies have indicated that the structures and nature of the complexes have a strong influence on the formation of brookite nuclei. Therefore, the titanium source is quite important for the selective synthesis of titania polymorphs. Application of the present approach allows the synthesis of rod-like brookite crystals with aspect ratios of 1 - 10, as well as snowflake-like crystal agglomerations. The mechanism of morphological control is also discussed.

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担当ページ：1-27   記述言語：英語 著書種別：学術書

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担当ページ：1-40   記述言語：英語 著書種別：学術書

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総ページ数：262   担当ページ：15-27   記述言語：日本語 著書種別：学術書

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総ページ数：262   記述言語：日本語 著書種別：学術書

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総ページ数：262   記述言語：日本語 著書種別：学術書

CiNii Research

記述言語：日本語 著書種別：学術書

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

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記述言語：日本語   出版者・発行元：日本塗装技術協会  

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記述言語：日本語   出版者・発行元：一般社団法人 日本物理学会  

<p>ルチル型の二酸化チタン結晶を水熱合成してできる結晶形は，グリコール酸添加により{110}面が発達して&lt;001&gt;方向に伸びる晶癖変化を示すことが知られている。本研究では、グリコール酸イオンのルチル結晶表面吸着の異方性を分子動力学シミュレーションにより調べ、グリコール酸添加によるルチル結晶の晶癖変化との関係を考察した。</p>

DOI： 10.11316/jpsgaiyo.71.2.0_2455

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）  

1372

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記述言語：日本語   出版者・発行元：日本結晶成長学会  

Control of crystal growth is rather important in the field of materials, because the shape directly affects their functional abilities. Our research group engages in hydrothermal synthesis of titanium dioxide, which is regarded as one of the representative ceramics, using water-soluble titanium complexes. The high chemical stability and peculiar molecule structures of these titanium complexes allowed us to use various compounds which play a role in control of crystal growth, resulting in the selective synthesis of four titanium dioxide polymorphs, that is, rutile, anatase, brookite and TiO_2(B), with a controlled shape. This paper summarizes our past study and reported researches on synthesis of titania polymorph crystals by classification of zero-, one-, two-, and three-dimensional structures.

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタン(TiO2)は光触媒として、抗菌、脱臭、汚染物質の分解などに利用されている。酸化チタンには常温常圧で8種類の結晶構造があり、天然に産出するものにはアナターゼ型、ルチル型、ブルカイト型がある。その中でもアナターゼ型とルチル型が安定でかつ、合成しやすいことから様々な用途に広く使われている。これに対し、ブルカイト型は合成が非常に困難であることから利用例や研究報告数が少ない。そこで本研究では、水溶性チタン錯体を出発原料としブルカイト型酸化チタンの水熱合成を行った。また、得られたブルカイト粒子を用いてブルカイト型酸化チタン薄膜の作製を行い、光誘起親水性及び光触媒機能評価を行った。

DOI： 10.14853/pcersj.2011S.0.439.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタン(TiO2)は抗菌・防汚・汚染物質の分解などに利用されている。酸化チタンの結晶構造にはRutile、Anatase、Brookiteなどがあり、合成の容易なRutile、Anataseは広い用途で利用されており、可視光応答化についても多々報告されているがBrookiteについての報告例は少ない。我々は、今までに新規水溶性プロセスのグリコール酸チタン錯体を用いて準安定層のBrookiteを水熱法を用いて比較的容易に合成することに成功している。本研究ではこの合成プロセスを用いて可視光応答型Brookiteを合成した。また、従来の合成法ではNH3を用いていたのに対し、新たにNフリーの合成法を開発した。

DOI： 10.14853/pcersj.2010S.0.2P158.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

当研究グループ独自の原料である水溶性チタン錯体を用いて酸化チタン光触媒を水熱合成した。錯形成剤としての酒石酸を調製し作製した酒石酸チタン錯体に適切な添加剤を加えることで、ルチル型酸化チタンナノ粒子とニードル状アナターゼ型酸化チタン粒子の合成に成功した。合成した２つの試料について、メタノールの気相分解実験およびシュウ酸水溶液の分解実験で光触媒機能を評価し、活性に寄与する要因を調べた。この２つの実験結果から、気相では活性に結晶型の他に比表面積も大きく影響することがわかった。一方、溶液中では比表面積は活性に大きく影響せず、分散性や結晶性等が活性に影響を与えると考えられる。

DOI： 10.14853/pcersj.2010S.0.1L21.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタン(TiO2)は光触媒として、抗菌、脱臭、汚染物質の分解などに利用されている。酸化チタンには常温常圧で8種類の結晶構造があり、天然に産出するものにはアナターゼ型、ルチル型、ブルカイト型がある。その中でもアナターゼ型とルチル型が安定でかつ、合成しやすいことから様々な用途に広く使われている。これに対し、ブルカイト型は合成が困難であることから利用例や研究報告は数少ない。そこで、本研究では水溶性チタン錯体を原料として、ブルカイト型酸化チタンの水熱合成を行い、得られたブルカイト粒子を用いたブルカイト型酸化チタン薄膜の作製を行い、親水性及び光触媒機能評価を行った。

DOI： 10.14853/pcersj.2010S.0.1L25.0

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

我々は水溶性チタン錯体を水熱処理することで、準安定相TiO2(B)を直接合成できることをこれまでに報告してきた。水溶性チタン錯体から得られたTiO2(B)粒子は40nm程度の板状ナノ粒子で非常に大きな比表面積を有していることをこれまでに確認している。しかし実際には凝集して数μm程度の大きな塊となっているため、本来よりも比表面積が減少し分散性も低い。そこで水溶性チタン錯体と有機溶媒によるW/Oエマルションをつくり、水溶性チタン錯体を微小な液滴として分散させ、水熱処理を行うことでTiO2(B)ナノ粒子の微粒子化、分散性向上を試みた。

DOI： 10.14853/pcersj.2009F.0.1N26.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

二酸化チタンは白色顔料として多量に用いられている材料であり、近年では光触媒としての利用や研究が盛んになってきている。二酸化チタンは一般的にルチル型とアナターゼ型の2種類の多形が利用されるが、ルチル型は高温焼成で合成されるため微粒子の合成はできていなかった。本研究では新規独自の原料である酒石酸チタン錯体を用い、水熱法を適用することで合成が困難とされてきたルチル型二酸化チタンのナノサイズ微粒子を合成することに成功したことを報告する。また、その生成メカニズムについての考察を述べる。

DOI： 10.14853/pcersj.2009F.0.1N24.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

天然にも存在する有機酸を配位子に有し、酸性から塩基性の幅広い条件において加水分解を起こさない水溶性チタン錯体を塩基性条件で水熱処理すると、合成が困難であるとされるブルッカイト型酸化チタンを単相で得ることができることをこれまでに見出した。今回、用いる水溶性チタン錯体の配位子の選択や反応水溶液を塩基性にするために用いるアンモニア水の添加量の調節により、一般的に見られるブルッカイトよりもアスペクト比の大きいブルッカイト粒子や、棒状粒子が分裂し形状がリボン状に変化した特異な形態を有するブルッカイト粒子の作製に成功したことを報告する。合わせて、水溶性チタン錯体からのブルッカイト生成機構についての考察を述べる。

DOI： 10.14853/pcersj.2009F.0.1N23.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタン(TiO<SUB>2</SUB>)は光触媒として、抗菌、脱臭、汚染物質の分解などに利用されている。酸化チタンにはいくつかの結晶構造があり、天然のものにアナターゼ型、ルチル型、ブルカイト型がある。その中でもアナターゼ型とルチル型が安定でかつ、合成しやすいことから広く使われている。ブルカイト型は合成が困難であることから報告は数少ない。そこで、本研究では水溶性チタン錯体を原料として、ブルカイト型酸化チタンの水熱合成を行い、水熱合成によって生成した生成物を用いたブルカイト型酸化チタン薄膜の作製を行った。

DOI： 10.14853/pcersj.2009F.0.2N05.0

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記述言語：英語  

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタンの主な結晶構造として、アナターゼ型、ルチル型、ブルカイト型がある。その中でブルカイト型は合成が困難であることから報告は数少ない。本研究ではブルカイト型酸化チタンの水熱合成及び光触媒活性の評価を行った。操作方法は、水溶性チタン錯体であるグリコール酸チタン錯体溶液に、種々の添加剤を加え、水熱処理することによりTiO2を合成した。得られた生成物をXRD・STEMによって、同定・観察し、粒形、結晶性について評価した。次に、光触媒活性を評価するため、メタノールの分解反応により発生したCO2をIRにより測定した。グリコール酸チタン錯体溶液を塩基性条件下で水熱処理をすることでブルカイト型TiO2を得ることができた。

DOI： 10.14853/pcersj.2009S.0.460.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酒石酸チタン錯体を出発原料として、酸化チタン光触媒を水熱合成した。合成時に種々の添加剤を加えたところ、ルチル型酸化チタンナノ粒子とニードル状アナターゼ型酸化チタン粒子の合成に成功した。前者は過酸化水素を添加することで、後者はエチレンジアミンを添加することでそれぞれ得ることができた。これらについてメタノールの気相分解実験より光触媒機能評価を行なった。その結果、ナノルチルはニードル状アナターゼに比べ2倍の比表面積を有していながら活性は低い値を示した。このことより、酸化チタンの光触媒活性は結晶構造に大きく依存していることがわかった。

DOI： 10.14853/pcersj.2009S.0.457.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

現在光触媒として利用されている酸化チタンTiO2の中でも準安定相であるTiO2(B)を、新規チタン材料である水溶性チタン錯体を原料として水熱法によって合成した。グリコール酸を配位子としたグリコール酸チタン錯体溶液に硫酸を添加して加熱処理することで単相のTiO2(B)が得られた。TiO2(B)の微結晶を蒸留水、HCl、NaOHなどの異なる溶液中で再度水熱処理を行い結晶成長させることで粒子サイズ、形態をコントロールすることができた。また、メタノールの気相分解反応によって得られたTiO2(B)試料の光触媒活性の評価を行った。

DOI： 10.14853/pcersj.2009S.0.459.0

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記述言語：日本語   出版者・発行元：The Society of Chemical Engineers, Japan  

DOI： 10.11491/scej.2009.0.366.0

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記述言語：日本語   出版者・発行元：The Society of Chemical Engineers, Japan  

DOI： 10.11491/scej.2009.0.337.0

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

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その他リンク： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18750177/

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

本研究では、新規化合物の水溶性チタン錯体の一つである酒石酸チタン錯体を出発原料として、水熱法によって酸化チタンの合成を行った。水熱処理時の種々の条件（錯形成剤量、添加剤等）を変化させることで、多型と粒子形態の制御を行った。添加剤として過酸化水素を用いると平均粒径10nmのRutile型酸化チタンナノ粒子、エチレンジアミンを用いると30×150nm程度のニードル状Anatase型酸化チタンの合成に成功した。また、合成したこれらの試料の光触媒活性をメタノールの気相分解によって評価した。

DOI： 10.14853/pcersj.2008F.0.348.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

アミノ酸であるセリンとトレオニンを含有する新規水溶性チタン化合物の開発に成功した。得られたアミノ酸チタン化合物は中性の水を溶媒とすることが可能であることから、チタンに対してアミノ酸がキレート配位することでチタンの持つ強い加水分解能を抑制した“アミノ酸チタン錯体”を形成しているものと考えられる。一連の水溶性チタン錯体と同様に塩基性条件下でも分解しないという高い安定性を有しており、新たなチタン系材料の原料として期待できる。また、これらの水溶性アミノ酸チタン錯体を用いて合成した酸化チタンは高い光触媒活性を有し、さらに、可視光応答性を示した。

DOI： 10.14853/pcersj.2008F.0.347.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

EDTAを配位子とする水溶性チタン錯体を調製し、それを水熱処理する事により合成が困難とされるブルカイト型酸化チタンを単相で合成する事に成功した。これまで、グリコール酸を配位子とする水溶性チタン錯体を用いブルカイトの合成及び添加物による形態制御について報告してきたが、塩基性でのみブルカイトが合成可能である為、グリコール酸錯体を用いた添加物によるブルカイトの形態制御には制限があった。EDTAを配位子とするチタン錯体は弱酸性から中性領域でブルカイト粒子が合成可能であることから、種々の添加物を使用する事が可能となった。本発表では、添加物によるブルカイト粒子の形態制御及び、得られた粒子の光触媒活性を報告する。

DOI： 10.14853/pcersj.2008F.0.349.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

本研究では、水溶性チタン錯体であるグリコール酸チタン酸錯体を原料として、人工物としてのみ存在が確認され、一般に合成が困難とされているB型酸化チタン(TiO2(B))の水熱反応による合成を目的とした。金属チタン粉末に過酸化水素水とアンモニア水を加えて溶解し、錯形成剤としてグリコール酸を添加することで安定なグリコール酸チタン酸錯体を作製した。この錯体溶液に添加剤として硫酸を加えた強酸性条件でオートクレーブを用いて水熱処理を行った。得られた試料はXRD測定の結果TiO2(B)の単相であることが確認された。またSTEMでの観察により太さ12nm、長さ50nm程度の棒状粒子が長軸方向を揃えて凝集していることが確認された。

DOI： 10.14853/pcersj.2008S.0.3H10.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

水溶性チタン錯体の水熱処理により得られるルチル型酸化チタン(TiO<SUB>2</SUB>)の形態が、錯体水溶液にグリコール酸を過剰量加えることで、ロッド状からウィスカー状に制御可能であることを見出した。得られるウィスカー状TiO<SUB>2</SUB>はc軸方向に異方成長しており、(110)、(-110)、(1-10)、(-1-10)に囲まれていることが分かった。合成したルチル型TiO<SUB>2</SUB>の光触媒活性を紫外光照射時におけるTiO<SUB>2</SUB>の光触媒作用によるしゅう酸の酸化分解反応により評価したところ、ロッド状粒子よりもウィスカー状粒子の方が比表面積が小さくとも高い光触媒能を有していることが分かった。したがって、ルチル型TiO<SUB>2</SUB>の形態を制御することによりその光触媒能を向上させることに成功したと言える。

DOI： 10.14853/pcersj.2008S.0.3H11.0

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

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記述言語：日本語   出版者・発行元：The Society of Chemical Engineers, Japan  

DOI： 10.11491/scej.2008.0.628.0

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

酸化チタンは紫外線照射下で脱臭・抗菌・殺菌・空気中や水中の汚染物質の分解などといった光触媒作用を示すことから、各種分野への適用に大きな関心が持たれ一部では実用化されている。前回の報告では合成例の少ないブルカイト型酸化チタンを合成し、その光触媒活性を市販のアナターゼ型酸化チタンと比較しブルカイトがアナターゼと同様に高い活性を有することを示した。また同時に更なる高活性化の為には比表面積の増加すなわち微粒子化が必要であることを報告した。そこで、近年金属酸化物ナノ粒子の合成例が報告されているマイクロ波水熱法を用いブルカイト型酸化チタンの微粒子化を試み高活性化を目指した。

DOI： 10.14853/pcersj.2007F.0.130.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

チタンは多種多様の機能性セラミックス材料に利用されており、優れたポテンシャルを持つ元素として今後もその利用が拡大していくことが期待されている。我々の研究グループではチタンを親水性の錯体にすることで、水溶液プロセスによるチタン系セラミックス材料の合成を行っている。本発表では水溶性チタン錯体の作製とその構造及び安定性に関する考察を述べる。ならびに水溶性チタン錯体を原料とした、水溶液を媒体とすることを特徴とする手法、（１）錯体ゲル法による種々のチタン酸塩の合成、（２）水熱法による酸化チタンナノ粒子とそれを用いた光パターニング、（３）水熱法によるブルカイト型及びB型酸化チタンの生成とそのメカニズム、について述べる。

DOI： 10.14853/pcersj.2007F.0.128.0

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記述言語：日本語   出版者・発行元：公益社団法人 日本セラミックス協会  

無害で安定な物質である酸化チタン(TiO<SUB>2</SUB>)は白色顔料や光触媒として多岐に渡る分野で利用されている。その性能は酸化チタンの形状にも依存し、形態を変化させることで特異な機能が発現することが知られている。本発表では、水溶性チタン錯体の水熱処理により得られるルチル型酸化チタンの形態制御について報告する。開始水溶液に添加物として加える有機酸の種類や量、水熱処理時間や温度により得られるルチル型酸化チタンのサイズやアスペクト比の制御が可能であることが分かった。また、その生成機構の考察についても述べる。

DOI： 10.14853/pcersj.2007F.0.129.0

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