研究者詳細 - 丹羽　健

論文 - 丹羽　健

分割表示 86 件中 21 - 40 件目／全件表示 >>

Synchrotron-Radiation Infrared Microspectroscopy of Marcasite-Type NiN<sub>2</sub> 査読有り

Soda, K; Kawada, T; Niwa, K; Hasegawa, M; Ikemoto, Y

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 91 巻 ( 4 ) 2022年4月

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：Journal of the Physical Society of Japan

The electronic structure of the marcasite-type NiN2, newly synthesized under high pressures and high temperatures, was investigated using synchrotron-radiation infrared (IR) microspectroscopy and first-principles calculations based on the density functional theory (DFT). The IR spectrum of the marcasite-type NiN2 showed characteristic low reflectance of the semiconductor with spectral features probably due to defects or lattice vibrations and free carriers. The effective free-carrier concentration in the marcasite-type NiN2 was estimated by fitting a Drude-Lorentz model for the optical response to be 1024-25 m-3, much less than those of normal metals (1028-29 m-3) and comparable to the estimated concentration of the thermally-excited carrier in the conduction band. The DFT predictions could semi-quantitatively explain the experimental findings; at 36 GPa, the marcasite-type NiN2 had a narrow gap between the Ni 3d aσ bands split in the distorted octahedral coordination of N neighbors.

DOI： 10.7566/JPSJ.91.044702

High pressure synthesis and the valence state of vanadium ions for the novel transition metal pernitride, CuAl<sub>2</sub>-type VN<sub>2</sub> 査読有り

Asano, S; Niwa, K; Sasaki, T; Gaida, NA; Hasegawa, M

DALTON TRANSACTIONS 51 巻 ( 7 ) 頁： 2656 - 2659 2022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：Dalton Transactions

A novel transition metal pernitride, CuAl2-type VN2, has been synthesized at a pressure above 73.3 GPa. The bulk modulus has been determined to be K0 = 347(12) GPa. By hard X-ray absorption spectrum measurements of VN2, the valence state of transition metal ions in pernitrides has been for the first time experimentally reported.

DOI： 10.1039/d1dt04310b

超高圧力下での新物質・新結晶の溶液結晶成長査読有り

長谷川正, 佐々木拓也, Nico A. GAIDA, 丹羽健

日本結晶成長学会誌 49 巻 ( 2 ) 頁： n/a 2022年

Pressure-Tunable Crystal Structure and Magnetic Transition Temperature of the Nowotny Chimney-Ladder CrGeγ Phase 査読有り

Sasaki, T; Noda, K; Gaida, NA; Niwa, K; Hasegawa, M

INORGANIC CHEMISTRY 60 巻 ( 19 ) 頁： 14525 - 14529 2021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：Inorganic Chemistry

A Nowotny chimney-ladder (NCL) chromium germanide (CrGeγ) with varying compositions has been synthesized under high pressure. Crystal structure parameters of the NCL CrGeγ have been calculated by Le Bail refinement based on the superspace group. The refined γof CrGeγ increases with the synthesis pressure, indicating an increasing Ge content. The NCL CrGeγ phases are ferromagnetic at T = 2 K regardless of their composition, and the magnetic transition temperature (TC) increases when the γbecomes higher. It is noteworthy that CrGe1.763 and CrGe1.774 synthesized at P = 10 and 14 GPa have magnetic transition temperatures of T = 295 and 333 K above room temperature, respectively. Surprisingly, the magnetic transition temperature has changed by δTC = 270 K, although the γvalues of the raw material and the sample synthesized at P = 14 GPa differ by only δγ= 0.05, corresponding to an atomic concentration of 0.62 atom %. The synthesis pressure acts as an essential parameter in tuning the composition of the NCL phase. Accordingly, the high-pressure synthesis may significantly control several physical characteristics of NCL phases by utilizing compositional and structural modulation.

DOI： 10.1021/acs.inorgchem.1c01887

Crystal and Electronic Structure of U<sub>7</sub>Te<sub>12</sub>-Type Tungsten Nitride Synthesized under High Pressure 査読有り

Chang, CC; Sasaki, T; Gaida, NA; Niwa, K; Hasegawa, M

INORGANIC CHEMISTRY 60 巻 ( 17 ) 頁： 13278 - 13283 2021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：Inorganic Chemistry

Tungsten nitride continues to drive fundamental interests because of its potential as a functional compound, which combines features such as high hardness together with thermal, chemical, and wear resistance. Here, we report a novel tungsten nitride phase synthesized from MoC-type WN0.6 and molecular nitrogen after laser irradiation at P = 70 GPa in a diamond anvil cell. This novel phase is quenchable at ambient pressure and determined to be U7Te12-type tungsten nitride and crystallizes in the hexagonal space group (P6) having lattice parameters of a = 8.2398(3) Å, c = 2.94948(14) Å, and V = 173.423(13) Å3. Tungsten atoms are coordinated to eight and nine nitrogen atoms, higher than previously reported tungsten nitrides. The bulk modulus is determined to be K0 = 312 (5) GPa (K0′ = 4.0 fixed), and DFT calculations predict that U7Te12-type W7N12 has a metallic nature.

DOI： 10.1021/acs.inorgchem.1c01633

Nitriding synthesis and structural change of phosphorus nitrides at high pressures 査読有り

Niwa, K; Iijima, Y; Ukita, M; Toda, R; Toyoura, K; Sasaki, T; Matsunaga, K; Gaida, NA; Hasegawa, M

JOURNAL OF RAMAN SPECTROSCOPY 52 巻 ( 5 ) 頁： 1064 - 1072 2021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：Journal of Raman Spectroscopy

The phase stability of γ-P3N5 and the possible formation of new phosphorus nitrides were investigated via high-pressure in situ Raman spectroscopy, X-ray diffraction measurements, and first-principles calculations up to approximately 80 GPa. In this study, γ-P3N5 was synthesized via the direct nitridation of black phosphorus at a pressure approximately above 12 GPa. The Raman spectrum, bulk modulus (K0 = 130.27(43) GPa), and compression behaviors (order of axial compressibility: βc > βa > βb) were experimentally measured for the first time. These experimental results were in good agreement with those of first-principles calculations. Our high-pressure in situ measurements and first-principles calculations revealed that γ-P3N5 persisted up to 80 GPa at room temperature. The compression of γ-P3N5 proceeded with the folding of the layer consisting of the corner- and edge-sharing PN4 and PN5. The present findings indicate that the P–N bonding with a low coordination number (PN4 and PN5) is preferable and stabilized for phosphorus nitride over a wide pressure range. However, laser heating between 67 and 70 GPa in the presence of nitrogen resulted in the formation of new PxNy, which included the possibility of a new high-pressure P3N5 phase. The Raman scattering measurements along with the decompression demonstrated that the local structure of the newly synthesized PxNy metastably persisted at atmospheric pressure. The present experimental and theoretical studies on phosphorus nitrides offer new insights into the high-pressure behaviors of covalent compounds consisting of highly coordinated polyhedra.

DOI： 10.1002/jrs.6079

Electronic Structures of Transition-Metal Pernitrides Studied Using X-ray Absorption and Photoelectron Spectroscopy 査読有り

Soda Kazuo, Kato Daiki, Komabuchi Mai, Terabe Toshiki, Takayama Shin, Ibaragi Toshiki, Kato Masahiko, Niwa Ken, Hasegawa Masashi, Takakura Shoichi, Nakatake Masashi

Journal of the Physical Society of Japan 90 巻 ( 4 ) 頁： 44710 - 44710 2021年4月

Electronic Structures of Transition-Metal Pernitrides Studied Using X-ray Absorption and Photoelectron Spectroscopy 査読有り

Soda Kazuo, Kato Daiki, Komabuchi Mai, Terabe Toshiki, Takayama Shin, Ibaragi Toshiki, Kato Masahiko, Niwa Ken, Hasegawa Masashi, Takakura Shoichi, Nakatake Masashi

Journal of the Physical Society of Japan 90 巻 ( 4 ) 頁： 44710 - 44710 2021年4月

Phase relations and thermoelasticity of magnesium silicide at high pressure and temperature 査読有り

Gaida, NA; Niwa, K; Sasaki, T; Hasegawa, M

JOURNAL OF CHEMICAL PHYSICS 154 巻 ( 14 ) 頁： 144701 2021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：Journal of Chemical Physics

Within the exploration of sustainable and functional materials, narrow bandgap magnesium silicide semiconductors have gained growing interest. Intriguingly, squeezing silicides to extreme pressures and exposing them to non-ambient temperatures proves fruitful to study the structural behavior, tune the electronic structure, or discover novel phases. Herein, structural changes and thermoelastic characteristics of magnesium silicides were probed with synchrotron x-ray diffraction techniques using the laser-heated diamond anvil cell and large volume press at high pressure and temperature and temperature-dependent synchrotron powder diffraction. Probing the ambient phase of Mg2Si (anti-CaF2-type Mg2Si, space group: Fm3¯m) at static pressures of giga-Pascals possibly unveiled the transformation to metastable orthorhombic anti-PbCl2-type Mg2Si (Pnma). Interestingly, heating under pressures introduced the decomposition of Mg2Si to hexagonal Mg9Si5 (P63) and minor Mg. Using equations of state (EoS), which relate pressure to volume, the bulk moduli of anti-CaF2-type Mg2Si, anti-PbCl2-type Mg2Si, and Mg9Si5 were determined to be B0 = 47(2) GPa, B0 ≈ 72(5) GPa, and B0 = 58(3) GPa, respectively. Employing a high-temperature EoS to the P-V-T data of anti-CaF2-type Mg2Si provided its thermoelastic parameters: BT0 = 46(3) GPa, B′T0 = 6.1(8), and (∂BT0/∂T)P = -0.013(4) GPa K-1. At atmospheric pressure, anti-CaF2-type Mg2Si kept stable at T = 133-723 K, whereas Mg9Si5 transformed to anti-CaF2-type Mg2Si and Si above T ≥ 530 K. This temperature stability may indicate the potential of Mg9Si5 as a mid-temperature thermoelectric material, as suggested from previous first-principles calculations. Within this realm, thermal models were applied, yielding thermal expansion coefficients of both silicides together with estimations of their Grüneisen parameter and Debye temperature.

DOI： 10.1063/5.0044648

Crystal and Electronic Structures of MoSi<sub>2</sub>-Type CrGe<sub>2</sub> Synthesized under High Pressure 査読有り

Sasaki, T; Kanie, K; Yokoi, T; Niwa, K; Gaida, NA; Matsunaga, K; Hasegawa, M

INORGANIC CHEMISTRY 60 巻 ( 3 ) 頁： 1767 - 1772 2021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：Inorganic Chemistry

Chromium germanides, namely, Nowotny chimney-ladder-phase CrGe1.77 and MoSi2-type CrGe2, were synthesized above 15 GPa or more via laser heating using a diamond anvil cell (LHDAC). MoSi2-type CrGe2, which is the most Ge-rich compound in the Cr-Ge system, crystallizes in the tetragonal structure with a space group of I4/mmm (no. 139) and lattice parameters of a = 3.24919(6) Å and c = 8.0523(3) Å and is isostructural with MoSi2. MoSi2-type CrGe2 has a deep pseudogap caused by the splitting of 3d orbitals with Cr, as evidenced by ab initio calculation. In this article, we have succeeded in synthesizing a binary compound between transition-metal and metalloid elements for the first time at high pressures above 10 GPa using the LHDAC. This pathway opens the possibility to explore more compounds in this system and may provide new insights into the fundamental interaction between these two elements.

DOI： 10.1021/acs.inorgchem.0c03240

Elasticity of nanocrystalline kyanite at high pressure and temperature from ultrasonic and synchrotron X-ray techniques 査読有り

Gaida, NA; Gréaux, S; Kono, Y; Ohfuji, H; Kuwahara, H; Nishiyama, N; Beermann, O; Sasaki, T; Niwa, K; Hasegawa, M

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 104 巻 ( 1 ) 頁： 635 - 644 2021年1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

Material properties, such as elasticity data at wide-ranging conditions of pressure and temperature, attract increasing attention for material and earth sciences. In particular, polycrystalline ceramics for next-generation photonic applications are nowadays fabricated by advanced syntheses techniques operating under elevated pressures and temperatures. Herein, the elastic properties of a synthetic transparent and reinforced aluminosilicate nanoceramic composed of triclinic kyanite with minor amounts of trigonal α-alumina crystals are investigated using in situ synchrotron X-ray diffraction and ultrasonic techniques at high-pressure (up to 11 GPa) and high-temperature (300-1500 K) conditions. This not only enables the determination of the equation of state (EoS) parameters by applying the pressure-volume-temperature (P-V-T) data to the high-temperature Birch-Murnaghan EoS but also yields the elastic moduli together with their P and T derivatives from the fit of the compressional and shear wave velocities to a finite strain EoS: KS0,300 = 186(2) GPa, K′S0,300 = 7.2(6), (∂KS0,300/∂T)P = −0.023(2) GPa K−1, G0,300 = 125(1) GPa G′0,300 = 2.3(2), (∂G0,300/∂T)P = −0.017(1) GPa K−1. On the basis of our acquired results, we propose to predict the elastic moduli of aluminosilicate ceramics by a linear function of the ratio of AlO6 octahedra and SiO4 tetrahedra within the constituting phases.

DOI： 10.1111/jace.17464

Thermal Expansion of Incompressible U<sub>2</sub>S<sub>3</sub>-Type Nb<sub>2</sub>N<sub>3 </sub>Synthesized in a Diamond Anvil Cell

Asano, S; Niwa, K; Sasaki, T; Gaida, NA; Hasegawa, M

INORGANIC CHEMISTRY 59 巻 ( 12 ) 頁： 7915 - 7918 2020年6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：Inorganic Chemistry

A novel niobium nitride, U2S3-type Nb2N3, has been successfully synthesized by nitridation of δ-NbN above approximately 30 GPa in a laser-heated diamond anvil cell. Nb2N3 crystallizes in the same orthorhombic structure (space group: Pnma) as η-Ta2N3. Nb2N3 consists of regular-shaped polyhedra, and the bulk modulus has been determined to K0 = 300(2) GPa. The low-temperature X-ray diffraction measurements have been successfully conducted for the tiny novel Nb2N3 between 297.7(5) and 106.3(3) K under ambient pressure. Nb2N3 shows no structural phase transition down to 106.3(3) K, and investigation of the linear thermal expansion coefficients yields αa = 3.36(9) × 10-6 K-1, αb = 5.39(10) × 10-6 K-1, αc = 6.77(15) × 10-6 K-1, respectively. Our study reveals that the incompressible novel nitride shows low thermal expansion behavior, which offers new insights for the development of functional nitrides and their crystal chemistry.

DOI： 10.1021/acs.inorgchem.0c01057

Crystal structures and electronic properties of Sn<sub>3</sub>N<sub>4</sub> polymorphs synthesized <i>via</i> high-pressure nitridation of tin

Niwa, K; Inagaki, T; Ohsuna, T; Liu, Z; Sasaki, T; Gaida, NA; Hasegawa, M

CRYSTENGCOMM 22 巻 ( 20 ) 頁： 3531 - 3538 2020年5月

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：CrystEngComm

The crystal structures, compression behaviors, and electronic properties of Sn3N4 polymorphs were investigated by means of high-pressure in situ measurements, transmission electron microscopy, and DFT ab initio calculations. The direct nitridation of tin above a pressure of 29.5 GPa by using a laser-heated diamond anvil cell resulted in the synthesis of highly crystalline monoclinic Sn3N4 which so far is consistent with the reported one. On the other hand, it was newly discovered that the monoclinic Sn3N4 undergoes phase transition twice along with decompression at ambient pressure. Advanced synchrotron X-ray powder diffraction measurements and TEM analyses on the recovered sample demonstrate that the newly recovered Sn3N4 crystallizes with orthorhombic symmetry and consists of irregularly shaped SnN5 and SnN6. DFT ab initio calculations reveal that this newly recovered orthorhombic Sn3N4 is an indirect band gap semiconductor having a narrower electronic energy gap than that of cubic spinel-type Sn3N4. The present results demonstrate that high-pressure nitridation is a powerful method to synthesize highly crystalline Sn3N4 polymorphs and reveal the new crystal chemistry of group IVA nitrides with respect to the variety of crystal structures and electronic properties.

DOI： 10.1039/d0ce00210k

Hydrogen Depth-profiles in Nb Hydrides Formed in Supercritical Water 査読有り

Soda Kazuo, Sugiura Shinya, Yamaguchi Kanta, Kato Masahiko, Niwa Ken, Hasegawa Masashi, Suzuki Kohtaku, Ishigami Ryoya, Ikenaga Eiji

e-Journal of Surface Science and Nanotechnology 18 巻頁： 152-158 2020年4月

Nanowire crystals of tantalum nitride grown in ammonium halide fluxes at high pressures

Gaida, NA; Sasaki, T; Liu, Z; Niwa, K; Hirozawa, M; Ohsuna, T; Hasegawa, M

APPLIED PHYSICS LETTERS 116 巻 ( 12 ) 2020年3月

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：Applied Physics Letters

Nanowire crystals of a tantalum nitride phase have been grown from epsilon-tantalum nitride and ammonium halide precursors at high pressures exceeding several gigapascals. Synchrotron x-ray diffraction and Transmission Electron Microscopy (TEM) observations revealed that they had crystallized in an unreported hexagonal structure with lattice parameters of a = 3.050(1) Å and c = 2.909(2) Å. The one-dimensional growth orientation was along the crystallographic [001] direction. Scanning TEM-EDX elemental analyses showed that the nanowire crystals were composed of tantalum and nitrogen with small amounts of oxygen. The presence of the melted ammonium halides combined with supercritical ammonia acting as a reactive flux at high pressure and temperature played a significant role in the nanowire crystal growth. Raman spectroscopy performed on several single crystal nanowires pointed toward metallic properties, and the temperature dependence of the magnetization measured by Superconducting Quantum Interference Device magnetometry suggested a superconducting transition about 6.2 K. The analysis of the compression behavior revealed an incompressible nature, and the bulk modulus was determined to be 363(6) GPa.

DOI： 10.1063/1.5140856

Microstructural effects on hardness and optical transparency of birefringent aluminosilicate nanoceramics 査読有り Open Access

Gaida N.A, Nishiyama N, Beermann O, Schürmann U, Masuno A, Giehl C, Niwa K, Hasegawa M, Bhat S, Farla R, Kienle L

International Journal of Ceramic Engineering and Science 2 巻 ( 2 ) 頁： 76 - 82 2020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：International Journal of Ceramic Engineering and Science

Transparent nanoceramics, synthesized at extreme conditions of high pressure and temperature, are new classes of materials highly attractive for photonic applications, such as optical windows, which require additional increased hardness and toughness. In this study, mechanical properties of transparent polycrystalline nanoceramics consisting of triclinic Al2SiO5 kyanite (~91.4 vol%) and trigonal Al2O3 corundum (~8.6 vol%) fabricated at high pressure (10 GPa) and temperature (1200-1400°C) were investigated. It is already known that the optical transparency of kyanite-based nanoceramics increases with decreasing average grain size. The present study shows that the hardness of these ceramics increases with decreasing grain sizes down to ~70 nm according to the Hall-Petch strengthening. This grain size seems to mark a transition range where an inverse Hall-Petch effect is indicated due to signs of a moderate hardness decrease at a smaller grain size of ~35 nm. The observed hardness-grain size relation can fairly be described by an existing composite model, which considers the crystals to be harder than the noncrystalline grain boundaries. Within the range of average grain sizes examined, the kyanite habit changes from more equant to more columnar. This behavior is associated with the observed strong crack deflection by the columnar kyanite grains with aspect (length to diameter) ratios ranging from ~2 to 10 and may positively affect the fracture toughness.

DOI： 10.1002/ces2.10036

超高圧力下での直接窒化反応による白金族金属二窒化物の創製査読有り

長谷川正, 丹羽健

応用物理 89 巻 ( 2 ) 頁： 87 - 91 2020年2月

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：公益社団法人応用物理学会

<p>白金族元素（Ru，Rh，Pd，Os，Ir，Pt）は常圧下では窒素に対して不活性であり，従来は窒化物を形成しないとされてきた．ところが，数十GPa以上の超高圧下での直接窒化反応を用いると，これらの金属の二窒化物が創製される．ここでは，金属二窒化物などの金属多窒化物という新しい物質群について，現在世界で展開されている物質科学研究の一端を紹介する．最初に，ダイヤモンドアンビルセルという超高圧発生装置とレーザー加熱を組み合わせた超高圧合成技術について説明する．次に，合成された白金族金属二窒化物の安定性，結晶構造，物性について簡単に紹介する．そして最後に，白金族元素以外の金属においても創製される二窒化物の研究例として，世界で唯一初めての単結晶育成に成功したCrの二窒化物について述べる．</p>

DOI： 10.11470/oubutsu.89.2_87

High-Pressure Synthesis and Crystal Structure of MoC-Type Tungsten Nitride by Nitridation with Ammonium Chloride

Sasaki, T; Ikoma, T; Sago, K; Liu, Z; Niwa, K; Ohsuna, T; Hasegawa, M

INORGANIC CHEMISTRY 58 巻 ( 24 ) 頁： 16379 - 16386 2019年12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：Inorganic Chemistry

A novel tungsten nitride, MoC-type WN, was synthesized at 6 GPa and 1200 °C via nitridation of tungsten by ammonium chloride as a nitrogen source. This compound is isostructural with γ′-MoC, which has a hexagonal structure with a space group of P63/mmc (No. 194). Micrometer-sized single crystals of MoC-type WN were grown in molten ammonium chloride flux. In addition, NaCl-type WN and WC-type WN were synthesized via nitridation by ammonium chloride at 6 GPa and 1000 °C. Ammonium chloride is appropriate as a nitrogen source for nitride synthesis under high pressure. The new WN phase crystallizes in the hexagonal structure with unit cell parameters of a = 2.89248(2) Å and c = 10.17069(7) Å. The chemical formula of MoC-type WN refined by the Rietveld analysis from powder X-ray diffraction data was WN0.60(1). The zero-pressure bulk modulus, K0, of MoC-type WN was determined to be 338(3) GPa, which can be expected to be a hard material.

DOI： 10.1021/acs.inorgchem.9b01945

Hydrogen-Storing Salt NaCl(H<sub>2</sub>) Synthesized at High Pressure and High Temperature Open Access

Matsuoka, T; Muraoka, S; Ishikawa, T; Niwa, K; Ohta, K; Hirao, N; Kawaguchi, SI; Ohishi, Y; Shimizu, K; Sasaki, S

JOURNAL OF PHYSICAL CHEMISTRY C 123 巻 ( 41 ) 頁： 25074 - 25080 2019年10月

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：Journal of Physical Chemistry C

X-ray diffraction and Raman scattering measurements, and first-principles calculations are performed to search for the formation of a NaCl-hydrogen compound. When the NaCl and H2 mixture is laser-heated to above 1500 K at pressures exceeding 40 GPa, we observe the formation of NaClHx with P63/mmc structure which accommodates H2 molecules in the interstitial sites of the NaCl lattice forming ABAC stacking. Upon the decrease of pressure at 300 K, NaClHx remains stable down to 17 GPa. Our calculations suggest the observed NaClHx is NaCl(H2). In addition, a hydrogen-richer phase NaCl(H2)4 is predicted to become stable at pressures above 40 GPa.

DOI： 10.1021/acs.jpcc.9b06639

High-Pressure Synthesis and Phase Stability of Nickel Pernitride

Niwa, K; Fukui, R; Terabe, T; Kawada, T; Kato, D; Sasaki, T; Soda, K; Hasegawa, M

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 2019 巻 ( 33 ) 頁： 3753 - 3757 2019年9月

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：European Journal of Inorganic Chemistry

The high-pressure nitridation of nickel was investigated using a laser-heated diamond-anvil cell. Marcasite-type nickel pernitride (NiN2) was synthesized at approximately 40 GPa, and it transformed into the tetragonal phase at approximately 3 GPa along with the decompression. The structural refinement of marcasite-type NiN2 at 36 GPa gives an N-N distance of 1.24 Å. The first-principles calculation reveals that the marcasite-type NiN2 is a narrow-gap semiconductor, and high-pressure in-situ X-ray diffraction measurements revealed a zero-pressure bulk modulus of 172(6) GPa. The axial ratios (c/a and b/a) of marcasite-type NiN2 are close to the upper-limit values of marcasite-type structures, which suggests that the stability of marcasite-type transition metal pernitrides strongly depends on the d-electrons.

DOI： 10.1002/ejic.201900489

　前のページ - 次のページ　

1
2
3
4
5