Article
Chemistry, Physical
Romain Vollondat, Stephane Roques, Celine Chevalier, Jeremy Bartringer, Jean-Luc Rehspringer, Abdelilah Slaoui, Thomas Fix
Summary: Type I (Na8Si46) or type II (Nax <= 24Si136) silicon clathrates films with a large surface area have been synthesized using a two-step process. The specific type of silicon clathrates phase can be selectively obtained by finely tuning the synthesis conditions. These films demonstrate higher optical absorption coefficients compared to diamond silicon in the visible light range, with type II films showing a direct bandgap suitable for photovoltaic applications. The surface defects and inhomogeneities of the as-prepared type II films have been significantly reduced through pressure annealing treatment.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Min Jin, Siqi Lin, Wen Li, Xinyue Zhang, Yanzhong Pei
Summary: This study focuses on the anisotropy of transport properties in n-type Mg3Sb2, revealing nearly isotropic transport properties in centimeter-sized single crystals, and uncovering the origins of low lattice thermal conductivity and superior electronic performance in the material.
MATERIALS TODAY PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yue Xin, Qiao Shi, Ke Xu, Zhi-Sen Zhang, Jian-Yang Wu
Summary: Mechanical properties of clathrate hydrates are influenced by the ability of host-guest molecules to form hydrogen bonds and the polarity of guest molecules, with structures containing guests with weak hydrogen bonding ability exhibiting brittle failure, while structures entrapping guests with strong hydrogen bonding ability showing ductile failure.
FRONTIERS OF PHYSICS
(2021)
Article
Crystallography
Haruhiko Morito, Kohei Futami, Kozo Fujiwara
Summary: This study investigates the influence of Na-Sn flux composition on the morphology and size of Na-Si clathrate crystals. The use of a flux leads to larger crystals with faceted surfaces. A Na9Sn4 solid phase precipitation inhibits the growth of Na-Si clathrate crystals at a specific ratio. Furthermore, synthesis conditions for obtaining type I crystals by conventional thermal decomposition in vacuum were established.
Article
Chemistry, Multidisciplinary
Carlos Lopez-Buena, Carlos Herreros-Lucas, Manuel Suarez-Rodriguez, Marius R. Bittermann, Alfredo Amigo, Sander Woutersen, Maria Gimenez-Lopez, Francisco Rivadulla
Summary: By adjusting the concentration of tetrabutyl ammonium and phosphonium salts in water, a unique and highly incompressible supramolecular liquid can be formed, with a dynamic structure similar to clathrates involving almost all water molecules of the solvent. Despite increased local order, the thermal diffusivity and compressibility of these liquids are significantly decreased compared to bulk water due to slower relaxation dynamics. This opens up the possibility of designing a new family of stable supramolecular fluids with potential technological applications in energy storage and conversion.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Nanoscience & Nanotechnology
Xiaolian Zhang, Pengcheng Zhai, Xiege Huang, Sergey Morozov, Bo Duan, Wenjuan Li, Gang Chen, Guodong Li, William A. Goddard
Summary: In this study, the intrinsic mechanical properties of thermoelectric clathrate Ba8Au6Ge40 were investigated using density functional theory calculations. The researchers found that the strength of Ba8Au6Ge40 varies depending on the loading direction, with {110}/<001> shearing and <110> tension being the weakest. The stretching and twisting of the Ge-Ge bonds cause distortion in the structure and ultimately lead to material failure.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Crystallography
Haruhiko Morito, Hisanori Yamane, Rie Y. Umetsu, Kozo Fujiwara
Summary: Type-II Na24Si136 clathrate octahedral single crystals surrounded by {111} facets were grown by evaporating Na from a molten mixture of Na4Si4 and Na9Sn4 at 823 K for 12 h. One of the obtained single crystals was used as a seed for the following single crystal growth of the type-II clathrate using the same method. The weight of the crystal grown with the seed was increased from 0.6 to 30.4 mg by repeating the seeded growth and was proportional to the surface area of the seed crystal.
Article
Chemistry, Physical
J. Suchanicz, K. Kluczewska-Chmielarz, M. Nowakowska-Malczyk, G. Jaglo, G. Stachowski, T. V. Kruzina
Summary: The phase transitions of unpoled and poled NBT single crystals were studied, and it was found that these transitions are of first-order and exhibit ferroelastic aspects. The transformations between rhombohedral-tetragonal and tetragonal-cubic phases result in a softening of mechanical properties, similar to improper ferroelastic transitions. The difference in internal friction between unpoled/poled states and between different poled directions can be attributed to the density difference of mobile ferroelastic twin walls.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Avantika Hasija, Subham Ranjan, Sarah Guerin, S. R. N. Kiran Mangalampalli, Satoshi Takamizawa, Deepak Chopra
Summary: This article introduces a polymorphic organic salt that exhibits both thermoresponsive and mechanoresponsive behavior at different temperatures. The study reveals that the single crystalline form of this salt displays reversible phase transformation, shape memory effect, and mechanical flexibility. By conducting experiments and calculations, the research reveals the differences in elastic modulus and resistance to elastic deformation among different forms of the salt.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Lanxian Shen, Kaiyuan Shen, Wen Ge, Jie Zheng, Baihua He, Shukang Deng
Summary: In this study, Sm-doped type-VIII single-crystalline clathrate SmxBa8-xGa16Sn30 thermoelectric material was successfully prepared via Sn-flux method, showing low solubility of Sm in Ba8Ga16Sn30 but significantly improved carrier mobility. The electrical properties exhibited irregular changes with the increase of initial Sm content, where the sample with x = 0.75 consistently showed high Seebeck coefficient and conductivity.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2022)
Article
Physics, Applied
Lihua Liu, Xiaojun Liu, Wei Zhang, Peizhu Liu, Ning Chen, Yang Li
Summary: This paper introduces magnetic Gd atom into type-I clathrate Eu8Ga16Ge30 for the first time, and finds that Gd doping not only reduces the magnetic entropy change of the sample, but also strengthens the second magnetic transition at low temperature, resulting in larger refrigerant capacity and relative cooling power.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2022)
Article
Materials Science, Multidisciplinary
Masato Ohnishi, Terumasa Tadano, Shinji Tsuneyuki, Junichiro Shiomi
Summary: The effects of strong phonon anharmonicity induced by the quadruple-well potential of guest atoms in type-I clathrate Ba8Ga16Sn30 were investigated. A first-principles-based self-consistent phonon (SCP) theory was used to analyze the phonon transport, including a coherent interbranch component. The experimental thermal conductivities were reasonably reproduced by considering both lattice and electron contributions. The analysis with the SCP theory showed that the hardening of guest modes resulted in an increase in lattice thermal conductivity at frequencies below those of the framework-dominant flat modes, leading to a slow decay of the total lattice thermal conductivity with increasing temperature. Detailed analysis revealed that the increase in low-frequency lattice thermal conductivity was attributed to the increase in group velocities and lifetimes of phonon modes below the flat guest modes, as well as the abnormal increase in lifetimes of phonon modes between the frequencies of the flat guest and framework modes with increasing temperature.
Article
Chemistry, Physical
S. Dinagaran, J. Gajendiran, S. Gokul Raj, S. Gnanam
Summary: The aim of this work was to grow organic single crystals of 4-Aminoantipyrine (4-AAP) and investigate their crystal structure, optical properties, thermal stability, material rigidity, and dielectric behavior. The experimental results showed that the 4-AAP single crystals exhibited good transparency and nonlinear optical characteristics, and their electrical conductivity and dielectric behavior changed with the applied frequency.
JOURNAL OF MOLECULAR STRUCTURE
(2023)
Article
Chemistry, Multidisciplinary
Chao Wang, Shunda Yang, Min Luo
Summary: This article provides an overview of recent advancements in adduct-type nonlinear optical crystals, focusing on their structures and properties. The coordination chemistry and disadvantages of adducts are analyzed, and the current synthesis methods and future directions for further exploration are discussed. Adduct-type NLO crystals possess the ability to achieve a harmonious balance among multiple property parameters.
Article
Nanoscience & Nanotechnology
Lin Ma, Wanpeng Li, Kaixiang Yang, Jianjun Bi, Jicun Feng, Jiabei Zhang, Zhengguang Yan, Xiaoyuan Zhou, Cuixiu Liu, Yuan Ji, Jacob C. Huang, Xiaodong Han
Summary: This study investigated the mechanical properties of mixed organic-inorganic halide perovskite single crystals and found that the presence of organic cations significantly affects the mechanical properties of OIHPs, highlighting their importance in enhancing performance.
Article
Nanoscience & Nanotechnology
Dengshan Zhou, Zhenghao Chen, Kazuki Ehara, Kodai Nitsu, Katsushi Tanaka, Haruyuki Inui
Summary: Research shows that the macroscopic mechanical strength of single crystals of equiatomic Cr-Mn-Fe-Co-Ni high entropy alloy, which are expected to develop short-range ordering during thermal annealing, is not affected. The hardness, critical resolved shear stress, and activation volume values of the alloy do not significantly vary with the annealing temperature.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Bhaskar Paul, Norihiko L. Okamoto, Misato Kusakari, Zhenghao Chen, Kyosuke Kishida, Haruyuki Inui, Shigeki Otani
Summary: The plastic deformation behavior of single crystals of three transition-metal diborides, CrB2, TiB2 and ZrB2, was investigated at different temperatures, showing differences in plastic flow behavior influenced by crystal orientation and critical resolved shear stress.
Article
Chemistry, Physical
Takuya Hatakeyama, Hongyi Li, Norihiko L. Okamoto, Kohei Shimokawa, Tomoya Kawaguchi, Hiroshi Tanimura, Susumu Imashuku, Maximilian Fichtner, Tetsu Ichitsubo
Summary: The study revealed that under conditions where the magnesium migration kinetics are sufficiently enhanced, MnO2 polymorphs can transform into Mg-including spinels and then rocksalt-like phases. Alpha-MnO2 was found to exhibit reversible magnesium intercalation at 150 degrees C, while lambda-MnO2 phase possessing spinel/rocksalt structure framework is thermally unstable.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Physical
Mikio Oomae, Takeshi Teramoto, Katsushi Tanaka
Summary: The variations in positive temperature dependence of yield stress for L12 intermetallic compounds in pseudobinary alloys of Co3(Al, W)-Co3Ti were investigated. The activation energies are intermediate values between those of Co3(Al, W) and Co3Ti, and the composition dependence of the temperature dependence of yield stress can be predicted from the physical properties of the base compounds.
Article
Multidisciplinary Sciences
Zhenghao Chen, Bhaskar Paul, Sanjib Majumdar, Norihiko L. Okamoto, Kyosuke Kishida, Haruyuki Inui, Shigeki Otani
Summary: The plastic deformation behavior of single crystals of ZrB2 and TiB2 at room temperature was investigated using micropillar compression tests, which revealed that plastic flow can be observed through specific slip systems with high critical resolve shear stress values.
SCIENTIFIC REPORTS
(2021)
Article
Materials Science, Multidisciplinary
Daixiu Wei, Liqiang Wang, Yongjie Zhang, Wu Gong, Tomohito Tsuru, Ivan Lobzenko, Jing Jiang, Stefanus Harjo, Takuro Kawasaki, Jae Wung Bae, Wenjun Lu, Zhen Lu, Yuichiro Hayasaka, Takanori Kiguchi, Norihiko L. Okamoto, Tetsu Ichitsubo, Hyoung Seop Kim, Tadashi Furuhara, Evan Ma, Hidemi Kato
Summary: Recently-developed high-entropy alloys (HEAs) have expanded the compositional space and mechanical properties by substituting the constituent metals with metalloids. Metalloid substitution increases strength by increasing local lattice distortion and short-range chemical inhomogeneities, while reducing stacking fault energy to discourage dynamic recovery.
Article
Chemistry, Inorganic & Nuclear
Takuya Hatakeyama, Norihiko L. Okamoto, Tetsu Ichitsubo
Summary: This study investigates the thermal stability of alpha, beta, gamma, delta, and lambda-type MnO2 polymorphs using DSC and HTXRD. Results show that the thermal stability order of the polymorphs is beta > alpha > gamma > delta approximate to lambda. The structure and phase transformations of each phase under high temperature conditions are discussed in relation to the bonding environment of oxide ions.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Takeshi Teramoto, Momoko Narasaki, Katsushi Tanaka
Summary: In order to understand the complex mechanism of solid-solution strengthening in high-entropy alloys (HEAs), this study evaluates the effective atomic radii of constituent elements experimentally and finds a different order compared to previous theoretical calculations. While theoretical calculations suggest a correlation between yield stress and average atomic displacement in HEAs, this correlation is not confirmed by experimental results in this study.
PHILOSOPHICAL MAGAZINE LETTERS
(2022)
Article
Multidisciplinary Sciences
Takuya Hatakeyama, Norihiko L. Okamoto, Satoshi Otake, Hiroaki Sato, Hongyi Li, Tetsu Ichitsubo
Summary: This study demonstrates that birnessite-type layered manganese dioxide with crystal water can serve as a well-balanced heat storage material due to its water-intercalation mechanism, high energy density, and validated driving force for intercalation, providing an optimal solution for low-grade waste-heat applications.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Xiatong Ye, Hongyi Li, Takuya Hatakeyama, Hiroaki Kobayashi, Toshihiko Mandai, Norihiko L. Okamoto, Tetsu Ichitsubo
Summary: Rechargeable magnesium batteries are promising candidates for future batteries due to their abundant resources and high energy density. This study compares the reaction behavior of different MnO2 cathodes in two electrolytes and highlights the importance of interfacial stability for practical applications.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Robert Josef Enzinger, Martin Luckabauer, Norihiko L. Okamoto, Tetsu Ichitsubo, Wolfgang Sprengel, Roland Wurschum
Summary: A detailed understanding of the kinetics of phase formation in fi-stabilised titanium is crucial for their applicability, but specialized measurement techniques are needed due to the complex nature and long timescales of the transformations. High-stability isothermal laser dilatometry was used to study the volume changes of Ti-21 at. pct V samples during phase formation. Different behaviors were observed between samples with different solute oxygen content, and the temperature ranges for diffusionless and diffusion-assisted isothermal w-formation as well as w-to-a transformation were determined. The results confirm recent findings on the distinction between diffusionless and diffusion-assisted isothermal w formation modes. Modelling of w-phase formation using Austin-Rickett kinetics revealed temperature-dependent formation rates, which were used to develop isothermal TTT-diagrams reflecting the strong influence of oxygen content.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Multidisciplinary Sciences
Kaoru Okamoto Yoshiyama, Norihiko L. Okamoto, Jun Hidema, Atsushi Higashitani
Summary: Far-ultraviolet radiation C light (far-UVC; 222 nm wavelength) has been considered as a safer light for killing pathogenic bacteria and viruses, but its effectiveness and potential biological damage compared to 254-UVC (254 nm wavelength) were unclear. This study found that 222-UVC caused slightly less DNA damage but had a significant effect on motility loss and severe damage to the sensory nervous system in a model organism, Caenorhabditis elegans. In contrast, 254-UVC had a higher impact on survival of eggs and chromosomal condensation. These results suggest that 222-UVC is less penetrating but causes more severe damage in tissues near the surface.
Article
Chemistry, Physical
Takeshi Teramoto, Kentaro Kitasumi, Ryota Shimohara, Yusuke Ito, Ryouga Shimizu, Katsushi Tanaka, Rintaro Ueji
Summary: The variation in chemical short-range order (CSRO) in Cr-Co-Ni medium entropy alloy was studied using electrical resistivity measurements. The results showed that thermodynamic equilibrium above 1075 K could not be achieved in conventional sample preparations. The resistivity quenched at different temperatures increased with lower annealing temperature, especially below 873 K. The activation energy was determined to be 240-270 kJ mol-1 and was similar to atomic diffusion in the Cr-Mn-Fe-Co-Ni high-entropy alloy, indicating a link between resistivity change and atomic arrangement. Compression tests on single crystals with varying degrees of CSRO showed that the degree of CSRO did not significantly affect the early stages of plastic deformation.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Norihiko L. Okamoto, Hiroki Yoshisako, Tetsu Ichitsubo
Summary: Layered manganese dioxide with K cations and water molecules shows reversible heat storage properties, but the initial irreversible capacity of water intercalation limits the energy density for subsequent cycles. This study analyzes the crystal structures of K-containing birnessite before and after heat treatment to understand the origin of the initial irreversible capacity. The analysis reveals that the ordered arrangement of K cations after heat treatment hinders the re-intercalation of excess water in subsequent cycles.
ENERGY STORAGE MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Hiroshi Tanimura, Norihiko L. Okamoto, Takao Homma, Yusuke Sato, Akihiro Ishii, Hitoshi Takamura, Tetsu Ichitsubo
Summary: This study investigates the ultrafast optical response of VTe2 and reveals the photoinduced phase transition process. It suggests that the high-temperature phase of VTe2 is induced within a picosecond through purely electronic effect and the phase transition dynamics proceed inhomogeneously via a nucleation mode.
