High Pressure Behaviors and a Novel High-Pressure Phase of Cuprous Oxide Cu2O

In the present study, we extensively explored the phase stabilities and elastic behaviors of Cu2O with elevated pressures up to 29.3 GPa based on single-crystal X-ray diffraction measurements. The structural sequence of Cu2O is different than previously determined. Specifically, we have established that Cu2O under pressure, displays a cubic-tetragonal-monoclinic phase transition sequence, and a novel monoclinic high-pressure phase assigned to the P1a1 or P12/a1 space group was firstly observed. The monoclinic phase Cu2O exhibits anisotropic compression with axial compressibility βb > βc > βa in a ratio of 1.00:1.64:1.45. The obtained isothermal bulk modulus of cubic and monoclinic phase Cu2O are 125(2) and 41(6) GPa, respectively, and the KT0’ is fixed at 4. Our results provide new insights into the phase stability and elastic properties of copper oxides and chalcogenides at extreme conditions.

Equation of state and some other properties of rock-salt AlN

The object of the present work is to study the equation of state (EOS) and the temperature dependence of the vibrational constant pressure heat capacity, the adiabatic bulk modulus Bs and the pressure derivative of the isothermal bulk modulus of cubic rock-salt Aluminum nitride under high pressure up to 100 GPa. In addition, the isothermal bulk modulus and the Debye temperature θD versus pressure at 1800 K are presented. Some structural and thermophysical properties used here are taken from our previous paper published in J. Electron. Mater. (2018) DOI: 10.1007/s11664-018-6169-x. The results obtained are analyzed and compared with other data of the literature.

Thermal properties of cubic zincblende thallium-phosphide from quasi-harmonic Debye model approximation

The thermal properties of cubic zincblende (B3) thallium - phosphide (TlP) compound under high pressure up to 12 GPa have been studied using the quasi-harmonic Debye model approximation. The relative unit cell volume, the isothermal bulk modulus, the first order derivative isothermal bulk modulus, the Debye temperature and the Grüneisen parameter are studied at zero-temperature and at standard ambient temperature (298 K) respectively. Our obtained values of the different previous quantities are in general in agreement compared to other theoretical data of the literature.

Pressure-Volume Behavior of Some Ionic Solids and Geophysical Minerals (CsBr)

Various forms of the equation of state for studying high-pressure behavior of solids have been developed by numerous investigators using phenomenological approaches. A common feature of the phenomenological equation is that they present the relationship between pressure and volume which can be expressed analytically involving two quantities only, viz Bo, B0’ respectively, the isothermal bulk modulus and its first pressure derivative, both at zero pressure. The present proposal which intend to compare the efficiency of the four equations under close examination reports the V/Vo versus P derived from the new modified forms of Murnaghan equations Birch equation (BE) and Freund-Ingalls (FIE) equation obtained for the best agreement with the available experimental data.

Volume Dependence of Thermodynamic Properties for Solids at high Temperatures

A new computing model on the volume dependence of the product αKT of the thermal expansion coefficient α and the isothermal bulk modulus KT is proposed straightforward in this paper. Based on this revised formula, the volume dependence of Grüneisen parameter, entropy, Anderson-Grüneisen parameter, and first pressure derivative of bulk modulus, respectively, are thus investigated. The calculated results agree well with the previous work for magnesium oxide, sodium chloride, lithium, sodium, and potassium.