Adiabatic, Isothermal, and Intermediate Pressure Derivatives of the Elastic Constants for Cubic Symmetry. II. Numerical Results for 25 Materials

Abstract

The purely adiabatic and the purely isothermal pressure derivatives of the elastic constants are calculated from the experimentally determined mixed isothermal‐adiabatic pressure coefficients of the elastic constants for 24 cubic crystals and one isotropic material. Also the linear combinations of the third‐order elastic constants that can be determined from these data are given for the different thermodynamic conditions. The first two expansion coeffcients of the volume versus pressure relation were determined from the ultrasonically measured elastic constants and their pressure coefficients and compared with Bridgman's high pressure volumetric data.

Shell Model Calculation of Microscopic Grüneisen Parameters for Rocksalt‐Type Materials

“…Although the shell model described contains six parameters the pressure dependence required for the calculation of the mode gammas will be considered only for the five parameters A , B, A", &', Y , whereas the core-she11 constant x defined by k = (e2/v) ~t will be assumed to be pressure independent. This assumption can be justified to some extent by the intuitive argument that a change in lattice constant will primarily affect the interionic forces, while intraionic 0.637 0.282 0.127 0.063 0.0598 0.0369 0.04806 0.0383 0.028 1.558 T a b l e 1 Elastic constants ell, c12, and c44 (in 10l2 dyn/cm2) and their pressure derivatives, static quency dielectric constant em, optical refractive index n = F m and its dimensionless presoptical frequency coo (in 10l3 s~~) , nearest neighbor distance v0 (in A), ionic masses Ml and 9.92 [37] 11.59 [37] 11.71 [37] 12.77 [37] 13.47 [37] 14.56 [37] 13.13 [ forces are not changed drastically. Besides, the pressure dependence of the electronic polarizability (1 d) can be described in terms of the pressure dependence of the shell charge Y and the first nearest neighbor shell-shell force constant R,, and is compatible with the assumption x = const.…”

Self‐Consistent Calculations of the Lattice Dynamics and Thermodynamics of Anharmonic Noble Metals

“…Approximately this &g. 1. Comparison of relative changes in the volume as functions of pressure; observed (dashed lines) [17] and calculated in the RSCPA for the Morse renormalized potential (solid curves);…”

Effect of Thermal-Neutron Irradiation on the Elastic Moduli of LiF

“…The pressure coefficients are taken from the compilation of Barsch and Chang. 25 The temperature coefficients of the elastic constants are further discussed later. The temperature coefficient of the volume, d\nV/dT (the volumetric thermal expansion), is a value estimated for the Debye temperature (1.5X10 -4 deg" 1 ) using the empirical formula given by Barsch and Chang.…”

“…The temperature coefficient of the volume, d\nV/dT (the volumetric thermal expansion), is a value estimated for the Debye temperature (1.5X10 -4 deg" 1 ) using the empirical formula given by Barsch and Chang. 25 The coefficient (dhiB/dp)/ (d InV/dp) is simply dB/dp, also given and corrected to its isothermal value by Barsch and Chang. The theoretical values of dlnB/dlnV for the sphere-in-hole model are described later in this section.…”