20 citations · 91 across the 15 of their papers we have counts for
16 papers
Nature of the order parameter of glass
Koun Shirai
In glass physics, order parameters have long been used in the thermodynamic description of glasses, but the nature is not yet clear. The difficulty is how to find order in disorder…
Residual Entropy of Glasses and the Third Law Expression
Koun Shirai
The third law of thermodynamics dictates that the entropy of materials becomes zero as temperature () approaches zero. Contrarily, glass and other similar materials exhibit nonz…
First-principles study on the specific heat jump in the glass transition of silica glass and the Prigogine-Defay ratio
Koun Shirai, Kota Watanabe, Hiroyoshi Momida
The most important characteristic of glass transition is a jump in specific heat . Despite its significance, no standard theory exists to describe it. In this study, first-…
First-principles study on the specific heat of glass at glass transition with a case study on glycerol
Koun Shirai, Kota Watanabe, Hiroyoshi Momida
The standard method to determine the transition temperature (Tg) of glass transition is the jump in the specific heat. Despite this importance, standard theory for this jump is lac…
Effect of magnetocrystalline anisotropy on magnetocaloric properties of AlFeB compound
Hung Ba Tran, Hiroyoshi Momida, Yu-ichiro Matsushita +4
It is well known that the temperature dependence of the effective magnetocrystalline anisotropy energy obeys the power law of magnetization in the Callen-Callen theory.…
Anisotropic magnetocaloric effect of CrI: A theoretical study
Hung Ba Tran, Hiroyoshi Momida, Yu-ichiro Matsushita +2
CrI is considered to be a promising candidate for spintronic devices and data storage. We derived the Heisenberg Hamiltonian for CrI from density functional calculation…
Interpretation of the apparent activation energy of glass transition
Koun Shirai
The temperature dependence of the viscosity of glass is a major concern in the field of glass research. Strong deviations from the Arrhenius law make the interpretation of the acti…
A thermodynamic description of the glass state and its application to glass transition
Koun Shirai
Many properties of solids such as the glass state are commonly treated as nonequilibrium phenomena, which involve many conceptual difficulties. However, few studies have addressed…
Revisiting the stable structure of the Cu complex in silicon
Takayoshi Fujimura, Koun Shirai
The photoluminescence (PL) spectrum of Cu-containing silicon has a sharp zero-phonon (ZP) band at 1.014 eV. The luminescence center corresponding to this band is called Cu a…
Interpretation of the Formation Volume of Defects in Crystal Growth
Koun Shirai
In the calculation of the formation enthalpy of a defect, a stress term accompanying the formation volume of the defect appears. This formation volume is conventionally interpreted…
Hydrogenation, dehydrogenation of -tetragonal boron and its transition to -orthorhombic boron
Naoki Uemura, Koun Shirai, Jens Kunstmann +2
Boron bulk crystals are marked by exceptional structural complexity and unusual related physical phenomena. Recent reports of hydrogenated -tetragonal and a new -orthorhombic…
State Variables and Constraints in Thermodynamics of Solids and Their Implications
Koun Shirai
There is a common view in thermodynamics that the behavior of a macroscopic system can be described by only a few state variables. Although this is true for many cases, it is uncle…
On the unattainability of absolute zero temperature and the Nernst heat theorem
Koun Shirai
It is sometimes argued that the unattainability of zero temperature is a consequence of the second law of thermodynamics. Historically, the independence of the unattainability of z…
Residual Entropy and Refinement of the Third-Law Expression
Koun Shirai
Although the third law of thermodynamics was established almost a century ago, it is not yet universally considered to be a fundamental law of physics. A major problem is that ther…
Structure, non-stoichiometry, and geometrical frustration of alpha-tetragonal boron
Naoki Uemura, Koun Shirai, Hagen Eckert +1
Recent discoveries of supposedly pure alpha-tetragonal boron require to revisit its structure. The system is also interesting with respect to a new type of geometrical frustration…
Impact of Ferroelectric Distortion on Thermopower in BaTiO3
Hiroaki Saijo, Kunihiko Yamauchi, Koun Shirai +1
We present a strategy for increasing thermoelectric performance by invoking ferroelectric distortion in a transition-metal oxide. By using an ab initio calculation approach with th…