研究者詳細 - 徳永　智春

論文 - 徳永　智春

分割表示 137 件中 21 - 40 件目／全件表示 >>

Applying an alternating current to strontium titanate minimizes the change in oxidation state caused by flash sintering

Seko, M; Inagaki, S; Tokunaga, T; Kobayashi, S; Nakamura, A; Yamamoto, T

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 44 巻 ( 5 ) 頁： 2965 - 2971 2024年5月

掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the European Ceramic Society

This study estimated the amount of oxygen deficiency in SrTiO3 polycrystals that were flash sintered under direct current (DC) and alternating current (AC) electric fields, mainly by using the fine structural change of the Ti L23-edges collected by electron energy-loss spectroscopy. The DC electric field corresponded to formation of the maximum amount of oxygen deficiency at approximately δ = 0.07 as SrTiO3−δ, which corresponds to a lattice expansion of roughly 0.1% as a lattice constant of SrTiO3. Furthermore, the oxygen deficiency was distributed unevenly. The formation of dislocation networks in DC-flash-sintered SrTiO3 polycrystals might be related to the lattice strain field caused by this nonuniform oxygen deficiency. In contrast, an AC electric field did not correspond to the oxygen deficiency of SrTiO3, which is similar to the results in thermally sintered SrTiO3 polycrystals.

DOI： 10.1016/j.jeurceramsoc.2023.12.046

Flash healing of Vickers microcracks formed on the (001) surface of cubic zirconia single crystals

Kayukawa, S; Katsuyama, Y; Kodaira, A; Tokunaga, T; Morita, K; Nakamura, A; Yamamoto, T

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 43 巻 ( 14 ) 頁： 6272 - 6278 2023年11月

掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the European Ceramic Society

Flash healing, a technique for microcrack healing using a flash event, has recently attracted attention for effective microcrack healing of ceramics. To investigate the diffusion-accelerated phenomena that occur during flash healing, the flash-healing behavior of Vickers indentation microcracks on (001) zirconia single crystals was investigated, mainly from the viewpoint of microstructure analysis of the healed microcracks. Scanning electron microscopy and atomic force microscopy showed that the surface microcracks were rapidly healed. However, scanning transmission electron microscopy showed that a row of pores remained along the original microcrack inside the crystal, and the crystallographic orientation relationship on both sides of the microcrack was restored to that of the original single crystal. Compared with the findings for healing without an electric field, the distance from the pore closest to the surface was larger and the total pore volume was smaller for flash healing. These results suggest that flash treatment increases lattice diffusion.

DOI： 10.1016/j.jeurceramsoc.2023.06.001

Near-full compaction within only 30 min of total sintering time by shrinkage-rate-controlled flash sintering in 3 mol % Y2O3-doped ZrO2 polycrystal

Ishino, Y; Koike, M; Kodaira, A; Tokunaga, T; Yamamoto, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 131 巻 ( 10 ) 頁： 600 - 607 2023年10月

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 development of a high-speed sintering method that can shorten the entire sintering time while guaranteeing the mechanical properties is very attractive as a sintering process for structural ceramic polycrystals. For this purpose, a sintering protocol that combines shrinkage-rate-controlled flash sintering, which controls the shrinkage rate to be constant with the use of an alternative current electric field, and a rapid furnace ramp were applied to 3-mol % Y2O3-doped ZrO2 (3YSZ). As a result, a 3YSZ sintered polycrystal with about the relative density of 99.5 % (6.06 g/cm3) could be successfully fabricated within 30 min as the entire sintering time, which includes the furnace-heating regime. The sintered 3YSZ polycrystal is confirmed to exhibit a Vickers hardness of approximately 1290 HV and a fracture toughness (KIC) of approximately 5.2 MPa m1/2, which are similar values to those obtained from a typical thermally sintered 3YSZ polycrystal.

DOI： 10.2109/jcersj2.23041

Structural Defect Effect on the Concentration Quenching of TbXY2-XO3 Phosphor Thin Films

Suzuki, S; Dazai, T; Tokunaga, T; Yamamoto, T; Katoh, R; Takahashi, R

JOURNAL OF PHYSICAL CHEMISTRY C 127 巻 ( 19 ) 頁： 9380 - 9387 2023年5月

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

This study investigates the structural defect effect on the luminescence properties of TbxY2-xO3 (x = 0-0.5) composition-gradient films using combinatorial pulsed laser deposition (PLD). TbxY2-xO3 films were grown on a SrTiO3 (001) substrate in an O2/He mixed atmosphere at PO2 = 1 × 10-4 Torr. A He buffer gas moderated the kinetic energy of the PLD plume and suppressed the resputtering of the film surface, resulting in the fabrication of defect-rich and poor TbxY2-xO3 films. The TbxY2-xO3 composition-gradient films exhibited varying green emissions from the Tb-doped Y2O3 films. The luminescence intensity of the defect-rich film was significantly weaker than that of the defect-poor film. Furthermore, concentration quenching of the luminescence occurred at high Tb concentrations. The analysis of the decay profiles of the luminescence as a function of the Tb concentration suggested two possible reasons for luminescence quenching: dynamic quenching induced by structural defects and static quenching induced by the shorter average distance of adjacent Tb ions. The investigation of the structural defect effect on the luminescence properties provides insights into the primary material parameters of phosphor materials and offers a pathway for enhancing their luminescence properties.

DOI： 10.1021/acs.jpcc.3c01679

Mechanistic consideration of ZnTe microspheres formation in a PVP-contained polyol system via hot injection method

Chau, YTR; Nguyen, MT; Tokunaga, T; Yonezawa, T

ADVANCED POWDER TECHNOLOGY 34 巻 ( 4 ) 頁： 103970 - 103970 2023年4月

掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Powder Technology

Zinc telluride (ZnTe) microspheres have been synthesized in a polyol system with adding various amount of poly(N-vinyl-2-pyrrolidone) (PVP, K-90) at 200 °C via a hot injection method. The smallest sized ZnTe microspheres obtained in this study had an average size of 634 nm through reaction for 48 h using 518 mg of PVP. A retrospective study was conducted to evaluate the formation process of ZnTe microspheres by conducting experiments from 0.2 h to 48 h. Nucleation and growth of ZnTe at the tips of Te rods in a PVP-contained polyol system were observed in sample reacted less than 1 h. More ZnTe microspheres and less Te rods were observed when the reaction was proceeded for longer time, suggesting that Te rods were the sacrificial template for the growth of ZnTe. Amount of PVP is the key factor of controlling dimensions of Te rods formed at the initial stage as well as the sizes of ZnTe microspheres by influencing the nucleation and growth rate of ZnTe. The obtained ZnTe microspheres at 48 h consisted of voids, which were originated by the detachment of ZnTe microspheres from Te rods after their growth.

DOI： 10.1016/j.apt.2023.103970

Microcrack healing in single-crystal cubic zirconia by thermal annealing 査読有り

Kayukawa, S; Katsuyama, Y; Kodaira, A; Tokunaga, T; Morita, K; Nakamura, A; Higuchi, K; Yamamoto, T

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 43 巻 ( 3 ) 頁： 1078 - 1086 2023年3月

掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the European Ceramic Society

Thermally healed Vickers microcracks perpendicular to (001) surface of cubic zirconia single crystals were investigated mainly with scanning transmission electron microscopy. The orientational relationship of areas containing healed microcracks was completely restored to that of the original single crystal, but a row of pores corresponding to the unhealed state remained where the original microcrack was located. Isolated pore formation proceeded from dislocation recovery via heat treatment, which brought the inner surfaces of the microcrack into contact, followed by diffusion bonding via surface diffusion. Once isolated pores were formed, the total pore volume did not significantly change by increasing the healing temperature, although pore sizes increased and the number of pores decreased. Ostwald ripening became pronounced in pore microstructure evolution when pore elimination was dominated by lattice diffusion after complete crystallographic restoration to a single crystal.

DOI： 10.1016/j.jeurceramsoc.2022.10.065

Flash self-joining of Y-TZP ceramics assisted with an AC electric field 査読有り

Nambu, K; Kitaoka, T; Morita, K; Soga, K; Tokunaga, T; Yamamoto, T; Masuda, H; Yoshida, H

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 106 巻 ( 3 ) 頁： 2073 - 2082 2023年3月

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 American Ceramic Society

In this study, flash joining experiments were conducted using an AC field on 3 mol% Y2O3‐stabilized tetragonal ZrO2 polycrystal (Y‐TZP) bodies. Furthermore, the necessary conditions to obtain an almost complete self‐joining of Y‐TZP bodies were clarified. The specimens were successfully joined by applying an AC field at 60 mA·mm−2 for 80 s at a furnace temperature of 1000°C, thus resulting in a successfully joined specimen with 92% of the flexural strength of the as‐sintered Y‐TZP body. Almost complete self‐joining of Y‐TZP was achieved at current densities above 30 mA·mm−2, and input energy densities of >24 J·mm−3. Both the input energy density and electric current were critical factors for producing the reliable joining of ceramics.

DOI： 10.1111/jace.18889

A technique to modify the photoluminescence intensity of β-Ga<sub>2</sub>O<sub>3</sub> polycrystals using an electric field during sintering 査読有り

Ono, R; Kodaira, A; Tokunaga, T; Yoshida, H; Yamamoto, T

JOURNAL OF LUMINESCENCE 254 巻頁： 119508 - 119508 2023年2月

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

Beta gallium trioxide (β-Ga2O3) is an attractive wide bandgap oxide that exhibits photoluminescent emission in the ultraviolet and blue/green regions. In the present study, we describe the tuning and enhancement of photoluminescent emission in the blue/green region by applying an instantaneous electric field during the sintering of a β-Ga2O3 green compact. Blue/green emission at around 480 nm increases by a factor of approximately 16 in β-Ga2O3 polycrystal prepared with the sintering protocol that a green compact was heated up to 1300 °C and an alternating current electric field (50 V/cm at 1000 Hz) was isothermally loaded. Considering that the enhancement occurs at the cathode side under a direct current electric field, the enhanced blue/green photoluminescence is likely due to an increase in the number of oxygen vacancies.

DOI： 10.1016/j.jlumin.2022.119508

Local Crystallization of Amorphous Aluminum Oxide Thin Film Using Electron Beam Irradiation by SEM

Tanahashi S., Okawara S., Tokunaga T., Yamamoto T.

Materials Transactions 64 巻 ( 1 ) 頁： 184 - 190 2023年1月

掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Transactions

Amorphous thin film thinned for transmission electron microscopy observation is reported to crystallize by electron beam (EB) irradiation of TEM. If thin film deposited on substrates can be crystallized by EB irradiation of scanning electron microscopy (SEM), new nanoscale devices can be fabricated such as electronic nanoscale circuits in amorphous thin films. Therefore, an amorphous AlOx (am-AlOx) thin film is deposited onto a Si substrate by atomic layer deposition (ALD) and point and area scan irradiation of EBs were performed by SEM. Then, structure and elemental analyses are carried out by TEM. Only the point EB irradiated area crystallized from the surface to the interface between am-AlOx and the Si substrate, and £-Al2O3 appeared. Moreover, the oxygen content of the not irradiated area close to the irradiated area was lower than that of the not irradiated area far from the irradiated area. These results show that the EB irradiated area was positively charged by the emission of secondary and Auger electrons under point irradiation conditions, and that oxygen was supplied by attracting its negative charge to the EB irradiated area. Also, the electrostatic repulsion between positively charged atoms and the structure relaxation due to electron excitation were additional driving forces for the crystallization.

DOI： 10.2320/matertrans.mt-n2022004

Apparent Sintering Activation Energy Estimated by Master Sintering Curves for 8 mol% Y<inf>2</inf>O<inf>3</inf> Doped ZrO<inf>2</inf> Polycrystals during Shrinkage-Rate Controlled Flash Sintering

Koike M., Kodaira A., Tokunaga T., Yamamoto T.

Materials Transactions 64 巻 ( 10 ) 頁： 2315 - 2320 2023年

掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Transactions

The apparent activation energy of sintering for 8-mol%-Y2O3-doped ZrO2 during shrinkage-rate-controlled flash sintering was determined using a master sintering curve. The activation energy during SCF sintering was found to decrease from approximately 700 to 430 kJ/mol with density. The activation energy in a high-density region is approximately similar value of lattice diffusion, 460 kJ/mol. The relative density range over which the decrease in activation energy occurred during SCF sintering was smaller than during thermal sintering and further moved to a lower temperature range. The increase in shrinkage rate at lower temperatures that occurs during SCF sintering could be considered to be related to this decrease in activation energy.

DOI： 10.2320/matertrans.MT-T2023002

Apparent Sintering Activation Energy Estimated by Master Sintering Curves for 8mol% Y2O3 Doped ZrO2 Polycrystals during Shrinkage-Rate Controlled Flash Sintering

Koike, M; Kodaira, A; Tokunaga, T; Yamamoto, T

MATERIALS TRANSACTIONS 64 巻 ( 9 ) 頁： 2315 - 2320 2023年

Variation of photoluminescence intensity depending on the timing of electric field application during isothermal flash sintering for 3mol% Y<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub> polycrystal 査読有り

Itoh, A; Tokunaga, T; Kodaira, A; Yoshida, H; Yamamoto, T

CERAMICS INTERNATIONAL 48 巻 ( 19 ) 頁： 28712 - 28717 2022年10月

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 International

The shrinkage process and the change in photoluminescence (PL) intensity during isothermal flash sintering were investigated for 3 mol% Y2O3–ZrO2 (3YSZ) polycrystals doped with 300 ppm Bi2O3 as a PL impurity centre. The PL intensity of 3YSZ is enhanced by isothermal flash sintering. However, the enhancement of the PL intensity was revealed to become smaller when flash-treatment was applied for thermally pre-sintered 3YSZ polycrystal. To maximize the efficiency of electric field on the enhancement of the PL intensity, the electric field needs to be applied throughout the sintering from the initial stage to the final densification. The necessity for continuing to apply the electric field until the densification is completed is due to the fact that the recovery of oxygen vacancies, the origin of the F+ band, must be suppressed.

DOI： 10.1016/j.ceramint.2022.06.185

Effect of He Buffer Gas on Pulsed Nd:YAG Laser Deposition of Eu<i><sub>x</sub></i>Y<sub>2-<i>x</i></sub>O<sub>3</sub> Phosphor Thin Films 査読有り

Suzuki, S; Dazai, T; Kawashima, K; Tokunaga, T; Yamamoto, T; Takahashi, R

ACS APPLIED ELECTRONIC MATERIALS 4 巻 ( 9 ) 頁： 4419 - 4426 2022年9月

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 Electronic Materials

We investigated the feasibility of using He buffer gas to moderate the kinetic energy of pulsed laser deposition (PLD) plumes during the growth of EuxY2-xO3phosphor films. The PLD growth of Y2O3films using a Nd yttrium aluminum garnet (Nd:YAG) laser results in expanded lattice parameters compared to those of the bulk crystals, indicating the presence of crystal defects in the Y2O3films. Ablation plumes with a high kinetic energy are generated by the Nd:YAG laser that operates at high energy densities, leading to defect formation. To moderate the kinetic energy without reducing the film growth rate, He buffer gas was used for the Nd:YAG-PLD growth of Y2O3films, resulting in the suppression of crystal defect generation. This process was demonstrated to improve the phosphor properties of EuxY2-xO3thin films grown via combinatorial PLD as the He buffer gas-induced reduction in crystal defect density enhances the phosphor properties of the EuxY2-xO3films. Using He buffer gas to moderate the kinetic energy of PLD plumes is expected to be useful in reducing the crystal defect density and improving the film characteristics.

DOI： 10.1021/acsaelm.2c00691

A liquid metal catalyst for the conversion of ethanol into graphitic carbon layers under an ultrasonic cavitation field

Kawasaki, H; Otsuki, T; Sugino, F; Yamamoto, K; Tokunaga, T; Tokura, R; Yonezawa, T

CHEMICAL COMMUNICATIONS 58 巻 ( 56 ) 頁： 7741 - 7744 2022年7月

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

Eutectic gallium indium (EGaIn) has drawn considerable research interest in potential liquid catalysis. Herein, we report that EGaIn liquid metal acts as a catalyst for the growth of a graphitic carbon layer from ethanol under ultrasonication. High-speed imaging demonstrated the formation of ultrasonic cavitation bubbles at the liquid metal/ethanol interface, which facilitated the pyrolysis of ethanol into graphitic carbon on the liquid metal surface.

DOI： 10.1039/d2cc02510h

Effect of electron beam irradiation in gas atmosphere during ETEM 査読有り

Tokunaga, T; Kawakami, T; Higuchi, K; Yamamoto, Y; Yamamoto, T

MICRON 158 巻頁： 103289 - 103289 2022年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Micron

Transmission electron microscopy (TEM) is used to observe the atomic structures of materials. Environmental TEM (ETEM) is a method wherein a gas can be evaluated and it has been used to observe the dynamic reaction between materials and gases at the atomic level. An electron beam (EB), which has a sufficiently high energy (exceeding a few tens of kilovolts), can be used to ionize gas molecules. Subsequently, the ionized molecules might react with the materials during ETEM. Therefore, the current generated by the ions and electrons were measured to verify the presence of ions generated due to the ionization of the N2 gas atmosphere during EB irradiation in ETEM. The electron energy loss spectra (EELS) were acquired from the N2 gas atmosphere to estimate the types of ions generated. The results demonstrated that ions and electrons were generated in the N2 atmosphere during ETEM and EB irradiation. Moreover, the EELS analysis indicated that the generated ion was N2+. The material observation conducted using gas ETEM can detect the reaction between gases, ions, and materials.

DOI： 10.1016/j.micron.2022.103289

The role of surface oxides and stabilising carboxylic acids of copper nanoparticles during low-temperature sintering

Tokura, R; Tsukamoto, H; Tokunaga, T; Nguyen, MT; Yonezawa, T

MATERIALS ADVANCES 3 巻 ( 12 ) 頁： 4802 - 4812 2022年6月

掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Advances

This article provides a detailed discussion of 1-hexanoic-acid-stabilised copper nanoparticles with an average diameter of ∼80 nm prepared from cupric oxide micro-powders for low-temperature sintering applications. The obtained fine particles were dispersed in dipropylene glycol using a bead mill to obtain a stable paste containing 50 wt% copper. Sintering experiments at temperatures in the range of 120-250 °C were performed under a nitrogen or 3%H2-N2 gas flow. The lowest resistivity, approximately three times that of bulk copper, was obtained at 250 °C. These particles exhibited good conductivity upon sintering under nitrogen only. 1-Hexanoic acid contributed to the acceleration of sintering by removing the Cu64O oxide layer of the particles and activating the surface. The dispersed copper paste and the copper layer after sintering were observed using SEM.

DOI： 10.1039/d1ma01242h

Excess oxygen-vacancy formed by FAST regime of direct-current electric field during flash sintering for 3 mol%-10 mol% Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> 査読有り

Morisaki, N; Tokunaga, T; Kobayashi, K; Kodaira, A; Yamamoto, T

CERAMICS INTERNATIONAL 48 巻 ( 9 ) 頁： 12091 - 12097 2022年5月

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 International

The amount of excess oxygen vacancies that are generated during FAST regime of direct-current flash sintering was estimated semi-quantitatively for 3 mol%–10 mol% Y2O3-doped ZrO2 (3–10YSZ) using the temperature dependence of the electrical conductivity. For the estimation, the electrical conductivity in the temperature range, where shrinkages are below a few percent, was used to avoid the effect of large microstructural changes on the electric conductivity. For all Y2O3 contents except 3YSZ, the amount of excess oxygen vacancies increased above a compact temperature of approximately 840 °C, which depended on Y2O3 content, and was highest in 8YSZ. Approximately 0.13% excess oxygen vacancy was generated by direct-current flashing in 8YSZ in the present electric field condition. In contrast, the increase in the excess oxygen vacancies is negligible in 3YSZ. The dependence of the amount of excess oxygen vacancies on the Y2O3 content was related possibly to the dependence of the electrode overvoltage on the Y2O3 content.

DOI： 10.1016/j.ceramint.2022.01.069

Anelasticityinduced by AC flash processing of cubic zirconia 査読有り

Masuda, H; Morita, K; Tokunaga, T; Yamamoto, T; Yoshida, H

ACTA MATERIALIA 227 巻頁： 117704 - 117704 2022年4月

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 Materialia

The defect physics is important for understanding the athermal effect of electric fields and/or currents on the enhanced ionic diffusion during flash sintering of ceramics. In this study, conventionally sintered 8 mol% yttria-stabilized zirconia with a fluorite cubic structure was processed by AC flash and subsequently quenched to partially freeze the flash-induced defect structures. The dynamic and quasi-static mechanical properties of flashed and non-flashed samples were evaluated by a sound velocity measurement and a nanoindentation technique to characterize the mechanical responses attributed to the flash-induced defects. A negligible change was confirmed in the dynamic elastic constants even after flash, while the quasi-static elastic properties of the flashed sample exhibited a considerable rate dependence (i.e., the slower the loading rate, the lower the measured contact modulus). The contact modulus of the flashed sample tested at the slowest loading rate in this study was reduced to approximately 72% of the non-flashed one, where the contact modulus was rate-independent. The time-dependent mechanical behavior was also confirmed during nanoindentation creep. Such rate- and time-dependent mechanical properties are characterized as anelasticity (i.e., viscoelasticity or pseudoelasticity in other terms), which can be attributed to stress-induced and thermally activated recoverable motions of point defects. The flash process of cubic zirconia possibly induced point defects associated with short-range structural change, which could be the origin of anelasticity.

DOI： 10.1016/j.actamat.2022.117704

Anisotropic Growth of Copper Nanorods Mediated by Cl<SUP>-</SUP> Ions 査読有り国際共著

Saw, MJ; Nguyen, MT; Kunisada, Y; Tokunaga, T; Yonezawa, T

ACS OMEGA 7 巻 ( 8 ) 頁： 7414 - 7420 2022年3月

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

Anisotropic growth to form Cu particles of rod and wire shapes has been obtained typically in a complex system that involves both organic capping agents and Cl- ions. However, the sole effect of Cl- ions on the formation of Cu wires has yet to be fully understood, especially in an organic system. This present work determines the effect of Cl- ions on the morphologies of Cu particles in an organic phase without any capping agents. The results revealed that anisotropic Cu rods could be grown with the sole presence of Cl- ions. The rods have the (011) facets as the long axis, the (111) facets as the tip, and the (100) facets as the side surface. By increasing the Cl- ion concentration, more Cu atoms contributed to the formation of Cu rods and the kinetic growth of the length and the diameter of the rods varied. This suggests that Cl- ions have preferential adsorption on the (100) Cu surfaces to promote the anisotropic growth of Cu. Meanwhile, the adsorption of Cl- to the (111) and (100) surfaces at high Cl- concentrations regulates the relative growth of the particle length and diameter.

DOI： 10.1021/acsomega.2c00359

Direct determination of a topmost atomic layer of (100) surfaces on (La<sub>0.3</sub>Sr<sub>0.7</sub>)(Al<sub>0.65</sub>Ta<sub>0.35</sub>)O<sub>3</sub> single crystals annealed in air by high-resolution scanning transmission electron microscopy 査読有り

Tokuda, Y; Irimoto, T; Nishikawa, N; Katsuyama, Y; Kobayashi, S; Tokunaga, T; Yamamoto, T

SURFACE AND INTERFACE ANALYSIS 54 巻 ( 3 ) 頁： 212 - 217 2022年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Surface and Interface Analysis

Herein, we investigated the surface of an (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) single crystal via scanning transmission electron microscopy (STEM) after annealing in air. We found amorphous mounds and atomically flat surfaces formed on the surface of the (100) LSAT single crystal subsequent to heat treatment. These surface mounds mainly constituted SrO, including ~50 at.% Al. The atomically flat surface showed a B-site termination determined by the direct surface observation at the atomic scale through HAADF-STEM. The atomic arrangements on the surface were accommodated by surface-mound formation and La evaporation. Consequently, the ordered structure disappeared because of the increase in the Ta content at the terminated B-site layer.

DOI： 10.1002/sia.7043

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/sia.7043

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