Article
Materials Science, Multidisciplinary
Jun Tang, Jinfan Chen, Pengchuang Liu, Ruizhi Qiu
Summary: The oxidation corrosion of metallic plutonium is an important issue for its applications, but the atomic mechanisms of such oxidation are still unclear. Through a first principles study, we investigated the oxygen diffusion in plutonium dioxide, sesquioxide, and their interface, and obtained dynamic parameters of oxygen diffusion in different oxides. We also discovered a dynamic equilibrium and an anisotropic pathway for oxygen diffusion at the oxide interface. These findings help to understand the mechanisms of plutonium oxidation at an atomic level and reveal prospects for the application of anisotropic orientation-relevant fluorite-structured oxides.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Chemistry, Physical
Alexander Bakulin, Lora S. Chumakova, Svetlana E. Kulkova
Summary: The oxygen absorption energy and migration barriers in titanium silicide with composition Ti5Si3 and hexagonal structure have been calculated, and the diffusion mechanism of oxygen in this material has been discussed. The obtained diffusion coefficient of oxygen in Ti5Si3 is comparable to experimental values for metal oxides.
Article
Chemistry, Physical
Alexander Bakulin, Sergey S. Kulkov, Svetlana E. Kulkova
Summary: In this study, analytic expressions for the temperature-dependent diffusion coefficient of oxygen in the alpha 2-Ti3Al alloy were obtained using Landman's method. The estimation of oxygen diffusion coefficient, pre-exponential factor, and activation energy was performed using migration barriers calculated by the first principle method within density functional theory. The validated method showed good agreement between the calculated diffusion coefficient of oxygen and available experimental data and theoretical results obtained within statistical approach.
Article
Crystallography
Nicolas Zapp, Denis Sheptyakov, Holger Kohlmann
Summary: Heteroanionic hydrides show great potential in functional materials design. By employing solid-state reactions, the cubic rare earth hydride oxides DyHO, ErHO, and LuHO were synthesized, each exhibiting unique crystal structures. Computational chemistry studies suggest that the formation of REHO compounds for smaller rare earth elements is less favorable compared to sesquioxides, requiring mild synthesis conditions for their synthesis.
Article
Chemistry, Physical
S. S. Setayandeh, E. G. Obbard, J. Stansby, D. Frost, Jack O. Astbury, C. L. Wilson, P. A. Burr
Summary: There is no consensus on the structure and composition of the epsilon phase in the W-B system. Ab initio calculations and experimental comparisons suggest that the epsilon phase is most likely a hypo-stoichiometric W2B5-x compound.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Chemical
Ricardo Urrego-Ortiz, Santiago Builes, Federico Calle-Vallejo
Summary: In this study, three correction schemes for PBE-calculated Gibbs energies of formation of 13 nitrogen compounds are analyzed. The results show that by correcting the errors in the NNO and ONO backbones and those in N-O and N-N bonds, the mean and maximum absolute errors are reduced to chemical accuracy. The study demonstrates that combining chemical intuition and automated optimization can swiftly enhance the predictiveness of DFT-GGA calculations of gases.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Gabriel L. Murphy, Zhaoming Zhang, Helen E. Maynard-Casely, Joshua Stackhouse, Piotr M. Kowalski, Thomas Vogt, Evgeny Alekseev, Brendan J. Kennedy
Summary: A combined experimental and theoretical investigation was conducted to study the compressibility of two SrUO4-x polymorphs (alpha and fi) under hydrostatic conditions. The study explains the contrasting chemical and mechanical behaviors of these polymorphs by differences in oxygen defect formation chemistry. The experimental data and ab initio calculations revealed that the expansion of the uranyl bonds in alpha-SrUO4 and fi-SrUO4 under hydrostatic pressures is due to the reduction of uranium formal oxidation state and the formation of oxygen vacancies. The difference in preferred lattice sites for oxygen defect formation leads to the significant difference in apparent bulk moduli between the two polymorphs.
Article
Chemistry, Multidisciplinary
Aamir Iqbal Waidha, Humera Khatoon Siddiqui, Yuji Ikeda, Maren Lepple, Sami Vasala, Manuel Donzelli, A. D. Fortes, Peter Slater, Blazej Grabowski, Ulrike Kramm, Oliver Clemens
Summary: A new anion-deficient perovskite material with unique oxygen vacancy ordering has been synthesized through a two-step heating process, showing G-type antiferromagnetic ordering confirmed by neutron powder diffraction, magnetic measurements, and DFT studies. The compound exhibits a high electronic conductivity and remarkable bifunctional catalytic activity, comparable to that of Ba0.5Sr0.5Co0.8Fe0.2O3-y, making it a promising candidate for efficient catalysts in oxygen-related reactions.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Shengsheng Liu, Linhan Liu, Zhiying Cheng, Jing Zhu, Rong Yu
Summary: The atomic structures of the (101) and (001) surfaces of Mn3O4 have been determined, showing that the (101) surface undergoes subsurface reconstruction while the (001) surface has Mn(III) ions in the outermost layer. These findings provide a microscopic understanding of the higher catalytic activity of the (001) surface compared to the (101) surface and could lead to the development of novel catalysts based on Mn3O4.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
J. Kong, S. K. Nayak, K. Co, S. Nayak, J. Wu, A. Feteira, K. A. Beyer, S. P. Alpay, A. Pramanick
Summary: The study utilized x-ray pair distribution function and density functional theory calculations to characterize the structure of cation-oxygen divacancy pairs in a Dion-Jacobson (D-J) layered perovskite, uncovering the relationship between local structural distortions and dielectric properties. The findings suggest that controlling atomic defects could potentially lead to significant control of dielectric properties in D-J layered perovskites.
Article
Materials Science, Multidisciplinary
Hou -Bo Zhou, Zi-Bing Yu, Feng-xia Hu, Jian-Tao Wang, Fei-Ran Shen, Jia-Zheng Hao, Lun-Hua He, Qing-Zhen Huang, Yi-Hong Gao, Bing-Jie Wang, Zhuo Yin, Zheng-Ying Tian, Jing Wang, Yun-Zhong Chen, Ji-Rong Sun, Tong-Yun Zhao, Bao-Gen Shen
Summary: This study reports the emergence of the Invar effect with excellent mechanical properties by modulating the electronic structure in LaFe11.6-xCoxSi1.4. The site occupancy of Co atoms was determined using neutron and X-ray diffraction, and ab initio calculations were performed to study the electronic band structure. The results show that the incorporation of Co atoms inhibits spontaneous magnetostriction and enhances the Invar effect in the ferromagnetic region of LaFe10.6Co1.0Si1.4.
Article
Chemistry, Physical
Maria Batuk, Daphne Vandemeulebroucke, Monica Ceretti, Werner Paulus, Joke Hadermann
Summary: This paper presents the first ever in situ 3D electron diffraction (ED) experiment in a gas environment, investigating the structure evolution of SrFeO2.5 material. The results show that SrFeO2.5 undergoes transformation into SrFeO2.75 and SrFeO3-delta structures under O-2 flow. However, during the reduction process in H-2 flow, the crystals return to their initial structure but without regaining the complete ordered structure.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
Article
Chemistry, Physical
Kohei Tada, Hiroyuki Ozaki, Koji Fujimaru, Yasutaka Kitagawa, Takashi Kawakami, Mitsutaka Okumura
Summary: The study found that surface interactions can tune chemical indices and that weak adsorption onto ionic solids with charge-dipole interactions can enhance diradical character.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
M. Krzystyniak, M. J. Gutmann, K. Refson, G. Romanelli, S. Rudic, S. C. Capelli, D. Fortes, O. Magdysyuk, J. I. Marquez Damian, G. Maciel-Pereira
Summary: This study investigates the interplay between phonon anharmonicity and nuclear quantum effects in hexamethylenetetramine (HMT) and its deuterated counterpart (DHMT) using a combination of experimental techniques and theoretical calculations. The results show that the combined effects of isotopic substitution, temperature, anharmonicity, and nuclear quantum effects lead to systematic discrepancies between theoretical predictions and experimental data. Additionally, a significant effect known as the reverse Ubbelohde effect, where deuteration decreases hydrogen bond length in HMT, is observed.
Article
Chemistry, Physical
Alexander V. Bakulin, Alexey S. Kulkov, Svetlana E. Kulkova
Summary: The projector augmented-wave method based on electron density functional theory is used to calculate the absorption energy and migration barriers of hydrogen in doped B2-TiFe. An analytical expression for the temperature-dependent diffusion coefficients of hydrogen in the doped alloy is derived using Landman's method. An approach to estimate the average jump rates of hydrogen for calculating the diffusion coefficient in doped alloys is developed. The effect of impurities on hydrogen diffusion in the alloy is discussed.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Physical
Yuta Yasui, Takafumi Tsujiguchi, Yuichi Sakuda, James R. Hester, Masatomo Yashima
Summary: This study analyzes the electrical conductivity and crystal structure of hexagonal perovskite derivatives Ba3MNbO8.5, and finds that Ba3WNbO8.5 has higher activation energy for conductivity compared to Ba3MoNbO8.5. The study also investigates the factors influencing conductivity and activation energy, and highlights the unresolved issue of O2/O3 disorder in Ba3MNbO8.5.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Inorganic & Nuclear
Kei Saito, Kotaro Fujii, Masatomo Yashima
Summary: BaY1/3Ga2/3O2.5 is a new type of mixed oxide-ion and proton conductor, with a high chemical and electrical stability, belonging to a new structure family of oxide-ion and proton conductors.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Taito Murakami, Toshiya Shibata, Yuta Yasui, Kotaro Fujii, James R. Hester, Masatomo Yashima
Summary: Investigation on solid solutions Ba7Ta4-xMo1+xO20+x/2 (x = 0.2-0.7) reveals high oxide-ion conductivity and stability under reducing conditions in Ba7Ta3.7Mo1.3O20.15, which indicates a strategy for the development of solid electrolytes based on hexagonal perovskite-related oxides.
Article
Chemistry, Physical
Hiroshi Yaguchi, Kotaro Fujii, Yoshinori Tsuchiya, Hiraku Ogino, Yoshihiro Tsujimoto, Masatomo Yashima
Summary: This study discovers RP oxychlorides Ba3Y2O5Cl2, Sr3Sc2O5Cl2, and Sr2ScO3Cl as a class of oxide-ion conductors. Ba3Y2O5Cl2 shows higher oxide-ion conductivity compared to Sr3Sc2O5Cl2, mainly attributed to its larger free and lattice volumes. The results suggest that RP oxychlorides are potential candidates for high oxide-ion conductivity.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Chemistry, Inorganic & Nuclear
Masashi Nakamura, Hirofumi Akamatsu, Kotaro Fujii, Yusuke Nambu, Yoichi Ikeda, Tomoki Kanazawa, Shunsuke Nozawa, Masatomo Yashima, Katsuro Hayashi, Kazuhiko Maeda
Summary: The study reveals that H-doped ASn0.7Y0.3O3-delta have almost identical bandgaps regardless of the A-site cation. Appropriate preparation conditions are essential for obtaining H-doped products with low defect densities.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Taito Murakami, Maxim Avdeev, Riho Morikawa, James R. R. Hester, Masatomo Yashima
Summary: Proton conductors are promising materials for clean energy, but most available materials require chemical substitutions to show sufficient conductivity, leading to difficulties in sample preparation and chemical instability. Recently, proton conductors based on hexagonal perovskite-related oxides have been gaining attention for their high proton conductivity without the need for chemical substitutions. In this study, three types of oxides with different oxygen-deficient layers were used to investigate the roles of specific layers in proton conduction. It was found that undoped beta-Ba2ScAlO5 exhibited high proton conductivity, while structurally related oxides alpha-Ba2Sc0.83Al1.17O5 and BaAl2O4 showed lower conductivity. Ab initio molecular dynamics simulations revealed the migration of protons through the double-octahedral layer, with the h' layer acting as a proton reservoir. These findings provide a strategy for developing high-performance proton conductors.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Maria Takahashi, Tsuyoshi Asatani, Tatsuki Morimoto, Yoshinobu Kamakura, Kotaro Fujii, Masatomo Yashima, Naoki Hosokawa, Yusuke Tamaki, Osamu Ishitani
Summary: In this study, new redox photosensitisers were synthesized, which can supply different numbers and reduction potentials of electrons to the catalyst in photocatalytic reactions, providing a new approach for the reduction of CO2.
Article
Chemistry, Multidisciplinary
Hiroshi Yaguchi, Daisuke Morikawa, Takashi Saito, Kenji Tsuda, Masatomo Yashima
Summary: This study reports a novel oxide-ion conductor material, LaBi2-xTexO4+x/2Cl, which exhibits high oxide-ion conductivity through the vacancy mechanism. LaBi1.9Te0.1O4.05Cl possesses an oxide-ion conductivity of 20 mS cm(-1) at 702 degrees C, surpassing the best Bi2V0.9Cu0.1O5.35 conductors below 201 degrees C. The material also shows excellent chemical and electrical stability, and the high conductivity is attributed to cooperative diffusion through interstitial oxygen sites in triple fluorite-like layers. These findings provide a new direction for the development of oxide-ion conductors.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Inorganic & Nuclear
Hong Yan, Kotaro Fujii, Houria Kabbour, Akira Chikamatsu, Yu Meng, Yoshitaka Matsushita, Masatomo Yashima, Kazunari Yamaura, Yoshihiro Tsujimoto
Summary: Researchers have successfully grown a new gallium oxysulfide single crystal, La4Ga2S8O3, with disulfide pairs using a KI molten salt. The disulfide pairs dominate the valence band maximum and conduction band minimum, making La4Ga2S8O3 a direct-type semiconductor with an optical band gap of 2.45 eV. This research suggests that band gap engineering using multiple anions is a promising approach for developing novel photocatalysts with suitable band gap energies for water splitting and high photocorrosion resistance.
INORGANIC CHEMISTRY
(2023)
Article
Multidisciplinary Sciences
Yuta Yasui, Masataka Tansho, Kotaro Fujii, Yuichi Sakuda, Atsushi Goto, Shinobu Ohki, Yuuki Mogami, Takahiro Iijima, Shintaro Kobayashi, Shogo Kawaguchi, Keiichi Osaka, Kazutaka Ikeda, Toshiya Otomo, Masatomo Yashima
Summary: This study used resonant X-ray diffraction and nuclear magnetic resonance techniques to reveal the hidden Mo/Nb chemical order in the disordered hexagonal perovskite Ba7Nb4MoO20, with Mo atoms predominantly localized near the ion-conducting layer. The findings provide a basis for the development of ion conductors and offer a new avenue for investigating hidden chemical order/disorder in materials.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Yugo Kikuchi, Yuta Yasui, James R. R. Hester, Masatomo Yashima
Summary: We report new hexagonal perovskite-related oxides Ba3W1+xV1-xO8.5+x/2, which have a higher bulk conductivity than the mother material Ba3WVO8.5. Increasing the excess W content in Ba3W1+xV1-xO8.5+x/2 leads to an increase in oxygen content, resulting in improved oxide ion conduction. These findings open new avenues in the science and technology of oxide ion conductors.
Article
Materials Science, Multidisciplinary
Riho Morikawa, Taito Murakami, Kotaro Fujii, Maxim Avdeev, Yoichi Ikeda, Yusuke Nambu, Masatomo Yashima
Summary: Ba2LuAlO5 is an oxide with high proton conductivities, high diffusivity, and high chemical stability without chemical doping. It is a hexagonal perovskite-related oxide with highly oxygen-deficient hexagonal close-packed h' layers, which can uptake a large amount of water. Proton migration mainly occurs around the cubic close-packed c layers at the interface. These results demonstrate that the highly oxygen-deficient and cubic close-packed layers are a promising strategy for high-performance proton conductors.
COMMUNICATIONS MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Takuya Ohmi, Iain W. H. Oswald, James R. Neilson, Nikolaj Roth, Shunta Nishioka, Kazuhiko Maeda, Kotaro Fujii, Masatomo Yashima, Masaki Azuma, Takafumi Yamamoto
Summary: In this study, a thiocyanate-stabilized pseudo-cubic perovskite FAPbI(3) with ordered columnar defects (alpha'-phase) is reported. The compound is stable at room temperature and the presence of the alpha'-phase reduces the transition temperature of delta-phase to alpha-phase. The defect-ordered pattern in the alpha'-phase forms a coincidence-site lattice at the twinned boundary of the single crystals.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Yuichi Sakuda, Taito Murakami, Maxim Avdeev, Kotaro Fujii, Yuta Yasui, James R. Hester, Masato Hagihala, Yoichi Ikeda, Yusuke Nambu, Masatomo Yashima
Summary: In this study, a new hexagonal perovskite-related oxide Ba7Nb3.8Mo1.2O20.1 with high oxide-ion and proton conductivity, as well as high chemical and electrical stability, was reported. The ion diffusion mechanism of this material was found to be based on the formation and breaking of dimers, resulting in high oxide-ion conduction. Additionally, proton conduction was achieved through proton migration in the hexagonal close-packed structure layers.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Takuya Ohmi, Iain W. H. Oswald, James R. Neilson, Nikolaj Roth, Shunta Nishioka, Kazuhiko Maeda, Kotaro Fujii, Masatomo Yashima, Masaki Azuma, Takafumi Yamamoto
Summary: The study presents a thiocyanate-stabilized pseudo-cubic perovskite FAPbI(3) with ordered columnar defects (α'-phase). This compound exhibits stable characteristics at room temperature and has potential applications in photophysical fields.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)