Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

© 2019 IOP Publishing Ltd. A SnI4 molecule lowers its symmetry from T d to C3v on the liquid-liquid transition. Because it is possible to lower the molecular symmetry without violating the crystalline symmetry, it is worth examining whether the deformation occurs in the crystalline phase field. Extended X-ray absorption fine structure (EXAFS) measurements on the crystalline state were carried out to investigate the change in the environment around a Sn atom at high pressures and temperatures. We could not find clear evidence on the symmetry change of molecules even close to the melting points, where the melting curve becomes abnormally flat against pressure. Indeed, no inconsistency was found when we assumed that the coordination number of a Sn atom remains unchanged in the temperature and pressure range examined. The situation remains true when the system entered the high-pressure crystalline phase on compression. We can propose a consistent scenario as to the structural change on the phase transformation. The incompressibility of a SnI4 molecule could be suitably quantified. The procedure enabled us to conclude the molecule is more than an order of magnitude incompressible than the lattice.

DOI： 10.1088/1361-648X/ab4cbc

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

High pressure hydrous phases with distorted rutile-type structure have attracted much interest as potential water reservoirs in the Earth's mantle. An in-situ X-ray diffraction study of beta-CrOOH was performed at high pressures of up to 6.2 GPa and high-temperatures of up to 700 K in order to clarify the temperature effect on compression behaviors of beta-CrOOH. The P-V-T data fitted to a Birch-Murnaghan equation of state yielded the following results: isothermal bulk modulus K-T0 = 191(4) GPa, temperature derivative ( partial differential K-T/ partial differential T)(P) = -0.04(2) GPa K-1, and volumetric thermal expansion coefficient alpha = 3.3(2) x 10(-5) K-1. In this study, at 300 K, the a-axis became less compressible at pressures above 1-2 GPa. We found that the pressure where the slopes of a/b and a/c ratios turned positive increased with temperature. This is the first experimental study indicating the temperature dependence of the change in the axial compressibility in distorted rutile-type M3+OOH.

DOI： 10.1080/08957959.2019.1642884

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

DOI： 10.7566/JPSJ.88.065003

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

DOI： 10.1088/1361-648X/ab0cf2

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

DOI： 10.1063/1.5061714

Web of Science

researchmap

Authorship：Lead author,　Corresponding author  

DOI： 10.7566/JPSJ.87.114006

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Ltd.  

A new ‘two-phase’ simulation method with which to accurately predict the melting curve is proposed. The method requires, as a starting configuration, generating a two-phase coexistence state by employing a suitable ensemble. Examining a change in volume ratio of the two phases upon varying temperature (pressure) under a fixed pressure (temperature) allows us to determine the phase transition point. The Clausius–Clapeyron relationship can then be implemented as a guide to predict the nearby phase transition point. The method was applied to determine the solid–liquid phase boundary of the modified Lennard–Jones system. A better accuracy, as that achieved by the non-equilibrium relaxation method (Asano Y, Fuchizaki K. J Phys Soc Jpn. 2017
86:025001), was obtained but with much less computational cost.

DOI： 10.1080/08927022.2017.1387657

Web of Science

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Physics Publishing  

The similarity in the shape of the melting curve of GeI4 to that of SnI4 suggests that a liquid-liquid transition as observed in liquid SnI4 is also expected to occur in liquid GeI4. Because the slope of the melting curve of GeI4 abruptly changes at around 3 GPa, in situ synchrotron diffraction measurements were conducted to examine closely the structural changes upon compression at around 3 GPa. The reduced radial distribution functions of the high- and low-pressure liquid states of GeI4 share the same feature inherent in the high-pressure (high-density) and low-pressure (low-density) radial distribution functions of liquid SnI4. This feature allows us to introduce local order parameters that we may use to observe the transition. Unlike the transition in liquid SnI4, the transition from the low-pressure to the high-pressure structure seems sluggish. We speculate that the liquid-liquid critical point of GeI4 is no longer a thermodynamically stable state and is slightly located below the melting curve. As a result, the structural change is said to be a crossover rather than a transition. The behavior of the local-order parameters implies a metastable extension of the liquid-liquid phase boundary with a negative slope.

DOI： 10.1088/1361-648X/aaa180

Web of Science

Scopus

PubMed

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The melting curve of MgO, an important compound dissociated from the component of the Earth's lower mantle, was predicted in this work by using a one-phase approach. The existing data for the melting points under pressures were used as input. The necessary thermodynamic information was supplemented by constructing the equation of state. The melting point near the core-mantle boundary was estimated to be approximately 6000 K.

DOI： 10.7566/JPSJ.86.064602

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

A pressure-induced structural change of a polymer isotactic poly(4-methyl-1-pentene) (P4MP1) in the melted state at 270 degrees C has been investigated by high-pressure in situ x-ray diffraction, where high pressures up to 1.8 kbar were applied using helium gas. The first sharp diffraction peak (FSDP) position of the melt shows a less pressure dependence than that of the normal compression using a solid pressure transmitting medium. The contraction using helium gas was about 10% at 2 kbar, smaller than about 20% at the same pressure using a solid medium. The result indicates that helium entered the interstitial space between the main chains. The helium/monomer molar ratio was estimated to be 0.3 at 2 kbar from the FSDP positions. These results suggest that the compressibility of the P4MP1 melt can be largely dependent on the pressure transmitting media. As the pore size is reversibly and continuously controllable by compression, we suggest that the P4MP1 melt can be an ideal porous liquid for investigating a novel mechanical response of the pores in a non-crystalline substance. Published by AIP Publishing.

DOI： 10.1063/1.4983508

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The existence of a network structure consisting of electrically neutral tetrahedral molecules in liquid SnI4 and GeI4 at ambient pressure was examined. The liquid structures employed for the examination were obtained from a reverse Monte Carlo analysis. The structures were physically interpreted by introducing an appropriate intermolecular interaction. A 'bond' was then defined as an intermolecular connection that minimizes the energy of intermolecular interaction. However, their 'bond' energy is too weak for the 'bond' and the resulting network structure to be defined statically. The vertex-to-edge orientation between the nearest molecules is so ubiquitous that almost all of the molecules in the system can take part in the network, which is reflected in the appearance of a prepeak in the structure factor.

DOI： 10.1088/1361-648X/aa5f09

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The critical parameters of the modified Lennard-Jones system were examined. The isothermal-isochoric ensemble was generated by conducting a molecular dynamics simulation for the system consisting of 6912, 8788, 10976, and 13500 particles. The equilibrium between the liquid and vapor phases was judged from the chemical potential of both phases upon establishing the coexistence envelope, from which the critical temperature and density were obtained invoking the renormalization group theory. The finite-size scaling enabled us to finally determine the critical temperature, pressure, and density as T-c = 1.0762(2), p(c) = 0.09394(17), and rho(c) = 0.331(3), respectively.

DOI： 10.7566/JPSJ.86.034003

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The melting curve of the modified Lennard-Jones system, which has been obtained by equating the free energies between the solid and liquid phases, was reinvestigated using the nonequilibrium relaxation method. The latter method satisfactorily reproduced the previous result with much simplified procedures.

DOI： 10.7566/JPSJ.86.025001

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A molecular liquid GeI4 is a candidate that undergoes a pressure-induced liquid-to-liquid phase transition. This study establishes the reference structure of the low-pressure liquid phase. Synchrotron x-ray diffraction measurements were carried out at several temperatures between the melting and the boiling points under ambient pressure. The molecule has regular tetrahedral symmetry, and the intramolecular Ge-I length of 2.51 angstrom is almost temperatureindependent within the measured range. A reverse Monte Carlo (RMC) analysis is employed to find that the distribution of molecular centers remains self-similar against heating, and thus justifying the length-scaling method adopted in determining the density. The RMC analysis also reveals that the vertex-to-face orientation of the nearest molecules are not straightly aligned, but are inclined at about 20 degrees, thereby making the closest intermolecular I-I distance definitely shorter than the intramolecular one. The prepeak observed at similar to 1 angstrom(-1) in the structural factor slightly shifts and increases in height with increasing temperature. The origin of the prepeak is clearly identified to be traces of the 111 diffraction peak in the crystalline state. The prepeak, assuming the residual spatial correlation between germanium sites in the densest direction, thus shifts toward lower wavenumbers with thermal expansion. The aspect that a relative reduction in molecular size associated with the volume expansion is responsible for the increase in the prepeak's height is confirmed by a simulation, in which the molecular size is changed.

DOI： 10.1088/0953-8984/28/44/445101

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We propose a novel approach with which to estimate the density of liquids. The approach is based on the assumption that the systems would be structurally similar when viewed at around the length scale (inverse wavenumber) of the first peak of the structure factor, unless their thermodynamic states differ significantly. The assumption was implemented via a similarity transformation to the radial distribution function to extract the density from the structure factor of a reference state with a known density. The method was first tested using two model liquids, and could predict the densities within an error of several percent unless the state in question differed significantly from the reference state. The method was then applied to related real liquids, and satisfactory results were obtained for predicted densities. The possibility of applying the method to amorphous materials is discussed.

DOI： 10.1088/0953-8984/28/39/395101

Web of Science

Scopus

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The melting curve of the modified Lennard-Jones solid is derived using a one-phase approach. The Pade approximation employed for solving the melting-curve equation converges at the middle stage, giving rise to the well-known Simon curve that satisfactorily captures the actual melting curve found from a molecular dynamics simulation over a pressure range of four orders of magnitude. This situation is justified because the solid under consideration was shown to satisfy the thermodynamic condition under which Simon's curve becomes exact. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physleta.2015.10.009

Web of Science

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

DOI： 10.11316/jpsgaiyo.71.1.0_3260

CiNii Books

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

An equation of state (EOS) was constructed for the modified Lennard-Jones (mLJ) solid. States not close to the melting point are accurately described by the EOS. A "pretransitional" behavior was detected for the temperature derivative of the bulk modulus near the temperature at which the melting curve bends appreciably.

DOI： 10.7566/JPSJ.84.085002

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

A model molecular crystalline GeI4 was examined using molecular dynamics simulation. The model was constructed in such a way that rigid tetrahedral molecules interact with each other via Lennard-Jones potentials whose centers are located at the vertices of a tetrahedron. Because no other interaction that can "soften" the intermolecular interaction was introduced, the melting curve of the model crystalline material does not exhibit the anomaly that was found for the real substance. However, the current investigation is useful in that it could settle the upper bound of pressure below which the model can predict properties of the molecular liquid. Moreover, singularity-free nature of the melting curve allowed us to analytically treat the melting curve in the light of the Kumari-Dass-Kechin equation. As a result, we could definitely conclude that the well-known Simon equation for the melting curve is merely an approximate expression. The condition for the validity of Simon's equation was identified.

DOI： 10.7566/JPSJ.84.064601

Web of Science

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

DOI： 10.11316/jpsgaiyo.70.2.0_1385

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

DOI： 10.11316/jpsgaiyo.70.2.0_1386

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

DOI： 10.11316/jpsgaiyo.70.2.0_2989

CiNii Books

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

In situ synchrotron x-ray diffraction measurements were carried out to determine the melting curve of the molecular crystal GeI4. We found that the melting line rapidly increases with a pressure up to about 3 GPa, at which it abruptly breaks. Such a strong nonlinear shape of the melting curve can be approximately captured by the Kumari-Dass-Kechin equation. The parameters involved in the equation could be determined from the equation of state for the crystalline phase, which was also established in the present study. The melting curve predicted from the equation approaches the actual melting curve as the degree of approximation involved in obtaining the equation is improved. However, the treatment is justifiable only if the slope of the melting curve is everywhere continuous. We believe that this is not the case for GeI4's melting line at the breakpoint, as inferred from the nature of breakdown of the Kraut-Kennedy and the Magalinskii-Zubov relationships. The breakpoint may then be a triple point among the crystalline phase and two possible liquid phases.

DOI： 10.7566/JPSJ.83.074603

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

We have proposed a modified Lennard-Jones (mLJ) potential to deal with problems, such as the accurate determination of the melting condition, in which an attractive interaction plays an essential role, but its range need not necessarily extend to infinity. An accurate phase diagram, including the triple and the critical points of the system characterized by the mLJ potential, has been investigated using mainly thermodynamic integration. To predict the thermodynamic behavior of the system, it is further desired to construct the equation of state (EOS) as accurately as possible. The modified Benedict-Webb-Rubin EOS was employed to this end. The 33 parameters involved in the equation were carefully determined in order for the EOS to be compatible with the temperature dependences of the virial coefficients as well as with an extremely large set of thermodynamic data obtained from our own molecular dynamics simulation performed over a wide fluid region. The resultant EOS was found to be not only sufficiently accurate at temperatures up to twenty times as high as the critical-point temperature but also effective in practical use.

DOI： 10.7566/JPSJ.83.034601

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

The Lennard-Jones (LJ) potential has been widely used, even beyond fluid science, as a standard form to express interparticle interaction. However, numerical computation and simulation requires some convention for dealing with the potential's infinite tail. This delicate problem can be circumvented by adopting a truncated potential. The functional form of the latter should mimic that of the original potential as closely as possible, while simultaneously minimizing artificial effects caused by the resultant discontinuities. The advantage of choosing such a truncated LJ potential, called the modified Lennard-Jones (mLJ) potential, is that the thermodynamic behavior of fluids can be predicted from the extensive knowledge base regarding the LJ fluid. In this study, the properties of the mLJ fluid were treated as perturbations of the LJ fluid case, and the discrepancies were expressed as density series expansions. The second virial coefficient of the mLJ fluid was well reproduced by this method. Reproduction of the liquid-vapor coexisting envelope was also satisfactory, except in the vicinity of the critical point. © 2013 The Physical Society of Japan.

DOI： 10.7566/JPSJ.82.124001

Web of Science

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The low-pressure crystalline phase of a molecular crystal, SnI4, has a rising melting curve that breaks abruptly at around 1.5 GPa, beyond which it becomes almost flat, with a slight maximum at about 3 GPa. Although the overall aspect of this melting curve can be captured by the Kumari-Dass-Kechin equation, the values for the parameters involved in the equation were definitely different from those predicted on the basis of the Clapeyron-Clausius relationship. On the other hand, the accuracy of our experimental data prevented us from judging whether the parameters are derivable from the Lindemann melting law, as shown independently by Kumari and Dass, and by Kechin. The Kraut-Kennedy and Magalinskii-Zubov relationships seem to be valid in the low-pressure region where the melting curve is rising. The breakdown of these relationships suggests a qualitative change in the intermolecular interaction upon compression, thereby making the melting behavior unusual. (C) 2013 AIP Publishing LLC.

DOI： 10.1063/1.4851396

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

By adopting the isothermal-isochoric ensemble instead of the isothermal-isobaric one, the density of the modified Lennard-Jones system could be specified unambiguously even under extremely low-pressure conditions. The Gibbs free energy of the gaseous state could thereby be calculated with sufficient accuracy. For practical applications of the free energy, the lowest correction in the virial expansion was found to be sufficient under pressure conditions below 0.001 epsilon/sigma(3), where epsilon and sigma are the energy and length parameters, respectively, of the modified Lennard-Jones potential. Comparison of this free energy with those for the condensed phases obtained hitherto gave well-defined sublimation points. These points then defined the equilibrium solid-gas phase boundary. The present study thus confirmed the location of not only a sublimation point found previously under marginally stable conditions of an isobaric ensemble, but also the triple point; its temperature and pressure were speculated to be 0.61 epsilon/k(B) and 0.0018 +/- 0.0005 epsilon/sigma(3), respectively, where k(B) denotes Boltzmann's constant.

DOI： 10.7566/JPSJ.82.033001

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

An in situ synchrotron x-ray absorption measurement was carried out to estimate the density of liquid SnI4. The characteristic densities of the low-and high-pressure liquids were found to be 4.6-4.7 and 4.9-5.0 g/cm(3), respectively, and their region is separated at around 1.7 GPa. The difference in density, although a slight amount of 0.3-0.4 g/cm(3), strongly suggests the existence of a weak but discontinuous phase transition at that pressure between the two liquid regions.

DOI： 10.7566/JPSJ.82.033003

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

An investigation of the precise determination of melting temperature in the modified Lennard-Jones system under pressure-free conditions [Y. Asano and K. Fuchizaki, J. Phys. Soc. Jpn. 78, 055002 (2009)] was extended under finite-pressure conditions to obtain the phase diagram. The temperature and pressure of the triple point were estimated to be 0.61 epsilon/k(B) and 0.0018(5) epsilon/sigma(3), and those of the critical point were 1.0709(19) epsilon/k(B) and 0.1228(20) epsilon/sigma(3), where epsilon and sigma are the Lennard-Jones parameters for energy and length scales, respectively, and k(B) is the Boltzmann constant. The potential used here has a finite attractive tail and does not suffer from cutoff problems. The potential can thus be a useful standard in examining statistical-mechanical problems in which different treatments for the tail would lead to different conclusions. The present phase diagram will then be a useful guide not only for equilibrium calculations but also for nonequilibrium problems such as discussions of the limits of phase (in)stability. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764855]

DOI： 10.1063/1.4764855

Web of Science

researchmap

Publisher：The Surface Science Society of Japan  

DOI： 10.14886/sssj2008.32.0_194

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

The molecular crystal of tin tetraiodide is known to exhibit unusual features under pressure, such as solid-state amorphization. The low-pressure crystalline phase has a melting curve with a maximum at about 1.5 GPa, dividing the liquid phase into two states with different structures. However, the thermodynamic properties of this solid phase are still unknown. For proper thermodynamic measurements for the solid phase, we present here the Parsafar-Mason and Birch-Murnaghan-Anderson equations of state for the phase as a predecessor. The validity of the equations was confirmed by recent experimental observations. As far as can be seen from the equations of state, no remarkable anharmonic properties are expected, in the sense that the thermal pressure is well described by a linear function of temperature, i.e., alpha K-T (where alpha and K-T are the coefficient of thermal expansion and the isothermal bulk modulus, respectively) is virtually independent of temperature. In addition to the equations of state, we also report a unique means of holding a chemically active sample, which we established through the in situ x-ray diffraction measurements for SnI4 at high pressures and temperatures.

DOI： 10.1103/PhysRevB.84.144105

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We have shown from in situ synchrotron x-ray diffraction measurements that there are two thermodynamically stable liquid forms of SnI4, depending on the pressure. Based on the liquid-liquid critical point scenario, our recent measurements suggest that the second critical point, if it exists, may be located in a region close to the point at which the melting curve of the crystalline phase abruptly breaks. This region is, unlike that of water, experimentally accessible with relative ease. (C) 2011 American Institute of Physics. [doi:10.1063/1.3637038]

DOI： 10.1063/1.3637038

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The pressure in an isothermal-isochoric (or constant-NVT for short) Gibbs ensemble, which consists of two coexisting phases in equilibrium as the subsystems, was derived in terms of the microscopic degrees of freedom of the ensemble. The usual virial expression for pressure was found to be valid only approximately for subsystems that compose the ensemble. Fortunately, however, application of the expression is acceptable within most of the two-phase region except in the vicinity of the critical point. This was directly confirmed by conducting the Monte Carlo simulations which generate the isothermal-isobaric (constant-NpT) Gibbs ensembles as well as the constant-NVT ones.

DOI： 10.1143/JPSJ.80.024003

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

A classical interaction site model is still of great value for a complex substance to which first-principles calculations are not easily applied. In simulations using file interaction site model, a tail of potential other than the Coulomb potential is usually ignored. However, such a cutoff of potential may not be justifiable under some thermodynamic conditions. or ill circumstances where precise structural and/or thermodynamic properties have to be investigated. Here, we consider I molecular system in which it molecule or an atomic cluster contains several interaction sites. These interaction sites are connected via. inverse power interactions. By attaching it virtual charge to all interaction site, all inverse power interactions, including the Coulomb interactions between true electric charges. are formally treated in a unified fashion. The periodicity introduced by the periodic boundary condition, employed ill Simulations to eliminate the effects Of surfaces, then allows LIS to adopt the idea of an Ewald Sum. thereby being free from the Cutoff. The Ewald sum is taken for the SUM of the interactions, making Use of ill, formula for the generalized zeta function proposed by the author. As all example, the potential energy of it Molecular crystal, SnI4, in the low-pressure Crystalline State, and of Solid argon is examined, where van der Waals interactions bring about cohesion in these crystals. The Lennard-Jones potential is employed to model the cohesive interaction. The treatment is extended to molecular dynamics as well. The equations Of Motion that call generate all isobaric ensemble are derived. The technical aspects when carrying Out large-scale Simulations utilizing the Ewald method are briefly mentioned.

DOI： 10.1143/JPSJ.79.024004

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

The well-known Lennard-Jones potential is modified in such a way that it smoothly vanishes at a certain distance. A system whose interparticle interaction is given by such a potential is referred to as a modified Lennard-Jones system, and is served as a standard system describing simple solids and fluids. A phase diagram is determined based on the free energies obtained through thermodynamic integration.

DOI： 10.1088/1742-6596/215/1/012123

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

Structure of the liquid forms of tin tetraiodide, SnI4, has been studied at high pressure and high temperature by synchrotron x-ray diffraction experiment. Using a new sample container, we managed to collect diffraction data with much better quality than before. The presence of two different liquid forms was verified. The structural change between these two liquid forms is expected to take place in a very narrow pressure range between 1.35 GPa at 850K and 2.03 GPa at 1000K.

DOI： 10.1088/1742-6596/215/1/012079

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

DOI： 10.1143/JPSJ.78.055002

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The discovery of a first-order phase transition in fluid phosphorus aroused renewed interest in polyamorphism in liquids with a locally tetrahedral molecular structure. We have performed in situ synchrotron x-ray diffraction measurements on tin tetraiodide, which consists of SnI(4) tetrahedral molecules at ambient pressure, and established that the liquid forms existing above and below 1.5 GPa, where the slope of the melting curve of the solid phase changes abruptly, have different structures. This discovery offers evidence of thermodynamically stable polyamorphism in general compounds as well as in elements. A possible phase diagram that includes the two amorphous states already found is proposed based on the pseudobinary regular solution model. The vertex-to-face orientation between the nearest molecules plays a key role in the transition from the low-pressure to the high-pressure liquid phase.

DOI： 10.1063/1.3109691

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Diffraction data from hexagonal boron nitride compiled through in situ synchrotron x-ray measurements under pressures and temperatures up to about 8 GPa and 1000 K, respectively, were analyzed in the light of Birch-Murnaghan's and Parsafar-Mason's equations of state. The isothermal bulk moduli at ambient conditions obtained from these equations almost coincide. However, the value, about 20 GPa, is appreciably small compared to the one reported previously. The x-ray diffraction patterns by which the current result is justified are presented. The possible origin of a large discrepancy in the values is discussed. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ssc.2008.09.031

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Synchrotron x-ray diffraction measurements were performed on liquid SnI4 up to a scattering vector of 25 A(-1), utilizing a horizontal two-axis diffractometer installed at the SPring-8 bending magnet beam line BL04B2 in Japan. An effective method based on the maximum entropy method was devised to transform the measured total structure factor to the reduced radial distribution function. The reliability of the density estimation is discussed.(c) 2007 American Institute of Physics.

DOI： 10.1063/1.2754265

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The expression known as Murnaghan's equation of state in high-pressure research community is mathematically a correct solution to the equation of bulk modulus but is valid only within a very limited parameter space. Moreover, the equation of state in question exhibits a peculiar behavior at high pressures when fitted to compression data. An alternative expression with a much wider range of validity is given. No peculiarity appears in the resultant compression curve. The latter expression thus provides a new tool as an infinitesimal-strain equation of state for quick estimate of compression characteristics of substances.

DOI： 10.1143/JPSJ.75.034601

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A recent experimental investigation into the low-pressure crystalline state of an SnI4 molecular crystal under high pressure has revealed that the melting points predicted from molecular dynamics simulations were too high. The short-range octupole-octupole intermolecular interaction, which plays an important role at high pressures, was newly introduced to the model to accommodate this effect. These interactions do indeed destabilize the crystalline state. However, the degree of destabilization was too small to quantitatively reproduce the experimental melting points. A possible origin of the discrepancy is discussed. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ssc.2004.08.003

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The location of the liquidus in the low-pressure crystalline phase of SnI4 was determined utilizing in situ x-ray diffraction measurements under pressures up to approximately 3.5 GPa. The liquidus is not well fitted to a monotonically increasing curve such as Simon's equation, but breaks near 1.5 GPa and then becomes almost flat. The results are compared to those from molecular dynamics simulations. Ways to improve the model potential adopted in the simulations are discussed. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1751397

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Glassy dynamics of fluid particles in a supercooled liquid is discussed on the basis of the time-evolution equation obtained through the dynamical density functional theory (DDFT). The advantage, brought about by the coarse-grained nature of the formalism, in treating such strongly correlated motion over other approaches, such as the mode-coupling theories and direct computer simulations, is emphasized. A direction in which the DDFT should prove its worth on examining the phenomena is suggested.

DOI： 10.1088/0953-8984/14/46/322

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

Isothermal-isobaric molecular dynamics simulations were carried out for SnI4 in its liquid state under hydrostatic pressure up to about 5 GPa. The equation of state was obtained from the virial pressure. which was found to be in good agreement with that derived by Boublik regarding a system consisting of hard-convex bodies as a reference fluid. The virial coefficients determined from the equation of state were presented so as to facilitate experimental confirmation.

DOI： 10.1143/JPSJ.70.1321

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The relaxation process to a scaling state which is a nonequilibrium steady state in evolving cellular structures, such as soap froths and grain systems, is investigated by computer simulation of the vertex model and phenomenology in two dimensions. Our results are as follows: (i) This relaxation is hierarchical, that is, the average size of a cell (the characteristic length of the system) relaxes rapidly at an early stage and then topological quantities associated with the shape of cells relax slowly at a late stage. (ii) The latter slow relaxation is well described by the stretched exponential function. (iii) The time exponent beta of the stretched exponential function is related to the power gamma of the distribution for the time interval of the topological change in the form gamma = 1 + beta.

DOI： 10.1143/JPSJ.69.2727

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The pressure-temperature phase diagram of SnI4 was investigated to examine the inherent instability of crystalline SnI4 in terms of undergoing pressure-induced solid state amorphization, by conducting molecular dynamics simulations prior to studies involving laboratory experiments. The SnI4 molecules are regarded as rigid tetrahedra interacting with one another via van der Waals forces. In order for the isothermal-isobaric ensemble to be achieved, the well-established Nose-Klein scheme combined with the momentum scaling method was adopted when carrying out the simulations. The system was carefully heated up under fixed hydrostatic pressure from the low-pressure crystalline state across the melting point, which was determined by monitoring the time-dependence of the mean square displacement of the molecules, whereas, on cooling, the liquid state remained supercooled down to room temperature. The slope of the liquidus in the phase diagram between the low-pressure crystalline phase and the liquid phase was found to be positive, implying that the low-pressure crystalline phase has little connection with solid state amorphization. An expected overall pressure-temperature phase diagram of SnI4 is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)50923-4].

DOI： 10.1063/1.481675

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：E D P SCIENCES  

Strongly correlated dynamics of fluid particles in a supercooled liquid is discussed on the basis of the mesoscopic kinetic equation involved in the dynamical density functional theory, focusing attention on the advantage of a spatio-temporally coarse-grained description. By virtue of the coarse-grained character, the time evolution of the density profile is effectively obtainable beyond the late beta-relaxation regime, skipping over microscopic processes. Application of the theory is proposed in discussing the correlation length of particle motion, which may be crucial in examining the effect of confinement.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

Isothermal-isobaric molecular dynamics simulations for molecular crystal SnI4 are performed to examine the thermodynamic stability of the low-pressure crystalline phase against melting. Radial distribution functions in the liquid state are presented which await experimental verification.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The crossover behavior from collective to local spin motions in diluted antiferromagnets is discussed using the canonical molecular dynamics method without introducing any ad hoc approximations to the equations of motion. The calculated dynamic responses are compared with the recent results obtained by neutron inelastic scattering experiments. (C) 1999 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0022-3697(99)00093-1

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOCIETY JAPAN  

DOI： 10.1143/JPSJ.68.2864

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Slow dynamics which shows up in supercooled liquid near the glass transition is discussed on the basis of the discretized version of the dynamical density functional equation which is the mesoscopic kinetic equation put forth recently in an attempt to go beyond the current mode-coupling theories. The discretization was realized through an appropriate mapping of the equation onto the kinetic lattice gas model in such a way that the master equation for the latter could approximately lead to the former upon coarse-graining of the spatio-temporal scales. The kinetic lattice gas model, which contains no ad hoc parameters except the direct correlation function of the reference liquid, is then solved for a hard-sphere liquid by using the ordinary Monte Carlo method to give successfully the thermally activated hopping process which is dominant at later times. Aspect of the free-energy landscape is also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0378-4371(98)00622-0

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The current mode coupling theory (MCT) of supercooled liquids and glass transition appears to be limited to the initial stage of freezing prior to glass transition despite its remarkable successes. In the hope of overcoming this limitation a theoretical framework is proposed which combines the mode coupling mechanism and the free energy barrier hopping which takes place in the glassy state. The new theory takes the form of a Fokker-Planck type equation for the probability distribution functional of density. The theory can be mapped onto a kinetic Ising model and some numerical consequences will be presented. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(98)00499-2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

Through the mapping onto the kinetic lattice gas model the dynamical density functional equation is solved by the Monte Carlo method in a deeply supercooled hard-sphere liquid, while focusing on how the system explores the free-energy landscape during a relaxation process. A variety of metastable states appear as the supercooling proceeds beyond the equilibrium crystallization point. Our approach is the first to reproduce the hopping transitions among these states as a solution of a mesoscopic kinetic equation.

DOI： 10.1143/JPSJ.67.2158

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The dynamical density functional equation put forth recently in an attempt to go beyond the current mode coupling theories of supercooled liquid and glass transitions is solved by mapping to the kinetic lattice gas model. Analyses of the dynamic structure factor in the initial stage of freezing reveal that the equation correctly captures the mode coupling mechanism of density fluctuations.

DOI： 10.1143/JPSJ.67.1505

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MINERALS, METALS & MATERIALS SOC  

Relaxation to a scaling state in grain growth has been investigated by computer simulation of the two-dimensional vertex model which expresses a grain system with small number of degrees of freedom. Two kinds of grain boundaries with low and high energies are taken into account. Starting with a random pattern, the system develops to coarsen and approaches a scaling state with the statistical self-similarity after long time.
This relaxation process is found to be hierarchical, i.e. the average grain size first follows a power law of time and then other quantities, such as the variances of grain size and edge number distributions, gradually approach constants.
It is shown that the latter slow relaxation is well described by the stretched exponential form which is defined by an inverse of exponential of time to a power less than one and is widely observed in amorphous materials. The origin of this slow relaxation is discussed by tracing each life of grain to find the relation between its topological change and the slow relaxation. It is concluded that this slow relaxation can be qualitatively explained by the defect diffusion model.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MINERALS, METALS & MATERIALS SOC  

Recently large-scale numerical computations, including the first principles calculations, regarding the interfacial energy between the two crystallines, which capture microscopic nature of materials concerned have been made. It has been believed that the details of the bonding at an interface are crucial in understanding the dependence of the interfacial energy on geometrical location of the interface. Nevertheless the similarity of the overall features of the curves of the interfacial energy obtained against variation of the parameters which specify the geometrical location of an interface for several materials suggests a common underlying physics which should not depend strongly on the material chosen. The present investigation is therefore to discuss the commonly observed characteristics in the energy curves from purely geometrical point of view. To this end I first clarify, taking the twist boundaries as an example to which the method is applied, the hierarchy in the geometrical construction of the coincident-site lattice by invoking the continued-fraction expansion algorithm for the transformation operator between the two lattice structures which are separated by the interface in question. Interfacial energies are then calculated against misorientation based on a two-dimensional version of the model put forth by du Plessis and van der Merwe, which turn out to reveal a fractal energy surface with cusps at every Sigma value. It is emphasized that these singularities are not attributable to the nature of the bonding but are of purely geometrical origin.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

Synchrotron x-ray diffraction study establishes a novel structure sequence in SnI4 at high pressures to 153 GPa. A new crystalline phase responsible for the metallization is observed above 7.2 GPa. The pressure-amorphized SnI4 emerging above 15 GPa crystallizes at 61 GPa into another new structure having an apparent fee lattice with a nearest-neighbor distance as short as 3.00 Angstrom. This provides evidence for the occurrence of molecular dissociation. Atomic arrangement in the nonmolecular phase and structural properties of the amorphous state an discussed.

DOI： 10.1103/PhysRevLett.79.4597

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

Isothermal-isobaric molecular dynamics simulations of molecular crystal SnI4 are carried out based on a model consisting of rigid tetrahedral molecules interacting via van der Waals forces. The hehavior of the crystal upon an increase in pressure is satisfactorily reproduced on both microscopic and macroscopic scales in the pressure regime in which the low-pressure phase is stable. In particular the compression curve obtained is in excellent agreement with the experimentally determined one. Upon further increase in pressure, however. no symmetry change is detected in the present simulations over the pressure regime in which the phase transformation and the subsequent solid state amorphization are experimentally found to take place.

DOI： 10.1143/JPSJ.66.1575

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

Neutron scattering studies have been performed to elucidate the martensitic transformation mechanism in a quenched Cu61Zn39 alloy. The TA(1)[110] phonon branch (e//[1 (1) over bar 0]) showed slight softening over the entire q-region in the parent phase as the transformation temperature was approached on cooling. No particular dip was observed even just above the transformation temperature, while the intensities of the quasi-elastic diffuse scattering developed near q = 1/6[1 (1) over bar 0] and 1/3[1 (1) over bar 0] positions in the parent phase. No anomaly was found in several other phonon branches. The structure of the beta(1) '' martensite phase was investigated, and a mixed phase of an orthorhombic structure and a monoclinic structure is proposed, which are both different from the previously reported structures. An annealing effect was observed to confirm the role of inclusions in the parent phase.

DOI： 10.1143/JPSJ.66.1033

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

Kinetic Ising model mapped from the dynamical density functional theory for dense fluid is simulated by the Monte Carlo method. This permits long time simulations which enable us to go over from relatively lower density fluid regions to high density freezing regions without difficulty.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：KYOTO UNIV  

Relaxation of domain structures (soap foam, grain aggregate, etc.) to a scaling state has been investigated by computer simulation. Our result is as follows: this relaxation has a hierarchical structure, i.e., the average domain size first relaxes and then the average domain shape relaxes slowly. The latter can be well described by the Kohlrausch anomalous relaxation law. The relation between the two relaxations is also discussed.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：TRANSTEC PUBLICATIONS LTD  

A significant step forward has been achieved in computer modeling of time-evolution of three-dimensional grain aggregates, by projecting the equation of motion for the grain boundaries with continuous degrees of freedom into that of grain vertices, thus leaving a finite set of equations of motion for vertices. This model is referred to as the vertex model. It is noted that such a coarse-graining can be carried out not in ad-hoc manner but in such a way that the grain edges are approximated by straight lines in the course of projecting out unimportant continuous degrees of freedom. However, we are immediately confronted with the fact that the grain faces bounded by these straight edges are not always planar in general which is characteristic of three-dimensional cellular systems.
To circumvent this difficulty supplementary vertices called virtual vertices are introduced on grain faces by which a unique triangulation of the faces can be achieved. The actual introduction of virtual vertices, which should still be simple enough to be practically implemented, has been performed in the following two ways; (i) Take the positions of virtual vertices as the centers of gravity of each grain face (center-of-gravity model). (i) Take the initial positions of virtual vertices as the centers of gravity as in (i), but their subsequent motions are determined selfconsistently by the equations of motion (virtual-vertex model).
Equations of motions of vertices are then readily derived for each case. Note here that some lower cutoff resolution below which the movement of vertices cannot be described by the equations of motion does exit because of the coarse-grained character of the vertex models. Such movements occurring in very limited spatial regions can be adequately described by local topology changes which can always be resolved into recombination processes between the two grains and/or tetrahedron annihilation process. In this way, dynamics of grain aggregates can be unambiguously described by the set of equations of motion for all the vertices together with the elementary topological processes. The model permits further refinements of arbitrary degree by increasing the number of virtual vertices in appropriate manner.
Grain growth kinetics is discussed on the basis of the vertex model by comparing the results obtained by the vertex model simulations with those obtained by the Potts model simulations.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

An effective computer modeling of time evolution of three-dimensional cellular systems like soap froths and crystalline grain aggregates has been devised, which captures the essence of difficult correlation effects of neighboring cells. This can be achieved by eliminating the continuous degrees of freedom besides the immediate vicinity of the center of a singular region of space, that is, an intersection of interfaces from the original full-curvature driven equation of motion of interfaces, thus leaving a set of equations of motion for such intersections, i.e. vertices. To actually carry out this projection operation each interface is divided into a set of two-dimensional simplexes. A derivation of the model equations is given in the most general possible form. Various results including topological characteristics of three-dimensional cellular patterns were obtained using the simpler version of these vertex equations, among which the result for the average growth rate of f-sided cells is presented. An application to some specific cellular systems is also discussed.

DOI： 10.1016/0378-4371(95)00224-U

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

The time evolution of three-dimensional cellular patterns is discussed on the basis of the vertex model which consists of a set of equations for the motion of vertices obtained from the full curvature-driven equation of motion of cell boundaries (faces) by a reduction in the degrees of freedom. Some difficulty in the earlier vertex models, originating from the fact that faces are non-coplanar, is now side-stepped by introducing virtual vertices as supplementary degrees of freedom. Equations of motion are then readily derived assuming that the whole process is purely dissipative. By solving these equations numerically, scaling properties concerning cellular pattern growth are obtained. In addition, geometrical features such as the three-dimensional versions of the Aboav-Weaire law and the Lewis law are verified with fair accuracy. We emphasize that our vertex model has the potentiality for efficient improvements of indefinite degree by introducing arbitrary numbers of virtual vertices. © 1995 Taylor &amp
Francis Group, LLC.

DOI： 10.1080/13642819508239038

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

A procedure is discussed concerning numerical lattice sums of quantities characterized by inverse power law and modulation wave vector. A relatively simple formula for the sum is derived for odd-dimensional lattice but for arbitrary power, modulation wave vector as well as lattice structure, which includes the sum of such as the Ruderman-Kittel-Kasuya-Yosida and the Friedel interactions as one of the special cases.

DOI： 10.1143/JPSJ.63.4051

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

A frustrated vertex model is proposed to elucidate some essential properties in proton glass. The frustration mechanism is clarified which arises from the geometric constraint, the so-called ice rule, rather than competing ferroelectric and antiferroelectric interactions. By comparing two order parameters which are obtained by exact thermal averaging and by Monte Carlo sampling, broken ergodicity as well as broken symmetry is examined. Estimation of the diffusion constant in a diffusion process in relevant configuration space allows us to discuss the ergodic convergence property in connection with the free energy surface structure.

DOI： 10.1142/S0217979294000828

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The effect of crystal orientation of grains on grain growth is investigated by computer simulation. A vertex model which includes the orientation dependence of grain boundary energy is used. It is shown that the orientation effect gives rise to more distortion and more diversity in the shape of the grains. Such a distortion in the shape of grains is measured by the moment tensor, for a quantitative discussion. It is also found that the 1/2-power growth law of the average size of grains still holds under such an anisotropic circumstance.

DOI： 10.1016/0378-4371(94)90442-1

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The continued-fraction expansion algorithm is utilized to clarify the hierarchy among the coincident-site lattice structures. Boundary energies are calculated against twist misorientation based on a two-dimensional version of the model suggested by du Plessis and van der Merwe in 1965, which reveal a fractal energy surface with cusps at very SIGMA value. The origin of the cusps and the effects of local structural relaxation on the boundary energies are discussed.

DOI： 10.1080/09500839308240947

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MINERALS, METALS & MATERIALS SOC  

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The ultrasonic pulse echo method and the X-ray and neutron diffraction methods have been used to investigate the lattice instability of the premartensitic beta-1 phase of a Cu-27.0Al-5.5Pd alloy under uniaxial pressure. The third order elastic constants and the [110]TA1 mode Grueneisen parameter show that the beta-1 phase is strongly anharmonic. This situation causes marked instability of the beta-1 phase toward the (110)[110BAR] shear under the [001] pressure. Such an instability also appears as a gradient change of the [110]TA1 phonon dispersion relation at the GAMMA-point (q = 0). Interplanar force constant analysis of the [110]TA1 phonon dispersion relations suggests that the martensite induced by the [001] pressure would have the 18R (or 9R) structure. The 2/3[110]q(max) diffraction anomaly is found only by neutron diffraction and it does not show any noticeable pressure dependence; the anomaly is not the precursor of the stress-induced martensitic transformation.

DOI： 10.2320/matertrans1989.33.203

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Sr2CuO2(CO3) were prepared at 1273 K and 0.01 MPa CO2 partial pressure in a flowing gas of O2-CO2 using a mixture of SrCO3 and CuO powders as a starting material. The compound has a tetragonal structure with lattice constants a = 7.8045(1), and c = 14.993(1) angstrom, and its space group is I4. The formula per unit cell is 8 Sr2CuO2(CO3), and measured and calculated densities are D(m) = 4.71 g/cm3, and D(x) = 4.81 g/cm3, respectively. The crystal structure was refined by Rietveld analysis on X-ray powder diffraction and neutron powder diffraction data. The final residuals (R(F)) were 4.31 and 4.27% for the X-ray and neutron data, respectively. The structure consists of deformed [CuO6] octahedrons and layers of ordered triangular CO3 groups. Sr atoms having eight near oxygen neighbors are between the [CuO6] octahedrons and the CO3 layers.

DOI： 10.1016/0921-4534(92)90941-5

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Present work is aimed to obtain a clear idea of the phase stabilities of the title oxide at temperatures from 10K to 900K. X-ray powder and single-crystal diffraction measurements and neutron high-resolution powder diffraction measurements were carried out for the samples annealed in several different atmospheres i.e. CO + CO2 or O2 + Ar mixed gas, air, vacuum at about 10(-3)Pa. Clear evidence that NiO6 octahedrons rotate in the bc-plane (b > c > a setting) in La2NiO4.00 at room temperature was obtained. Shape of a magnetic peak 011 shows some broadening at temperatures below 70K i.e. LTO2 range.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The present study by X-ray and neutron diffraction methods is concerned with the omega-like peak appearing at the positions (H +/- 2/3, K +/- 2/3, L +/- 4/3) and (H +/- 2/3, K +/- 2/3, L -/+ 4/3) in the reciprocal lattice of the quenched beta(1) phase with the Heusler type structure of AuCuZn2. The obtained results indicate evidently that the omega-like peak is neither due to the omega phase formation as is the case of Zr alloy nor precursor phenomenon of the martensitic transformation. It is originated from a certain kind of regular arrangement of vacancies in the incompletely ordered B2 phase: the vacancies are responsible for the ordering reaction to the Heusler type structure occurring at about 670 K. They are frozen into the Heusler phase formed by quenching, and hence the quenched Heusler phase exhibits the omega-like peak as observed. The peak disappears with vacancy annihilation from the Heusler type beta(1) phase. Characteristics of both the [111]LA and [112BAR]TA phonon dispersion relations also support this conclusion.

DOI： 10.2320/matertrans1989.32.1011

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Trans Tech Publications, Ltd.  

DOI： 10.4028/www.scientific.net/msf.56-58.299

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

DOI： 10.1103/PhysRevB.42.10405

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

DOI： 10.1103/PhysRevB.42.9420

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/08957959008246127

researchmap

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

DOI： 10.1103/PhysRevB.40.4740

Web of Science

PubMed

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

DOI： 10.1103/PhysRevB.39.9260

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

Web of Science

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_2716

researchmap

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_1498

researchmap

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_2964

researchmap

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_2691

researchmap

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

researchmap

Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (bulletin of university, research institution)  

researchmap

Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (bulletin of university, research institution)  

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publishing type：Internal/External technical report, pre-print, etc.  

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (bulletin of university, research institution)  

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publishing type：Lecture material (seminar, tutorial, course, lecture, etc.)  

researchmap

Language：English   Publishing type：Meeting report  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：INT UNION CRYSTALLOGRAPHY  

DOI： 10.1107/S010876739607852X

Web of Science

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：English   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

researchmap

Language：Japanese   Publisher：一般社団法人日本物理学会  

CiNii Books

researchmap

Language：English   Publisher：The Japan Society of Applied Physics  

CiNii Books

researchmap

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2024.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

researchmap

Event date： 2023.3

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.9

Language：English   Presentation type：Poster presentation  

researchmap

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (invited, special)  

researchmap

Event date： 2021.3

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2020.12

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.2

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon, France  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：English   Presentation type：Oral presentation (general)  

Venue：Bayreuth, Germany  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：English   Presentation type：Poster presentation  

Venue：Lyon, France  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

researchmap

Language：English   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：English   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：English   Presentation type：Oral presentation (general)  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap