A Grüneisen Relation on Constant‐Pressure Lines

Abstract

Gruneisen's constant, y , is ideally temperature-independent on constant-volume lines; a similar constant, A, which is ideally temperature-independent on isobaric lines, has been found. The comparison between y and A shows that both expressions contain the ratio of the volumetric thermal expansion coefficient to the specific heat capacity; y has an additional temperature dependence due to the thermal part of the compressibility, whereas A has only a slight thermal component due to the volume per unit mass. A has been chosen so that A = y at the point where the temperature and pressure are both zero. For most materials it is expected that A 2 y with a different temperature dependence. It is shown empirically for a selection of ceramics that A is nearly temperature-independent and has a value between 0.7 and 1.4.

Measurement of anharmonicity of phonons in the negative thermal expansion compound Zn(CN)2 by high pressure inelastic neutron scattering

“…Grüneisen parameter is defines in terms of the ratio of the thermal expansion and the specific heat [20].…”

“…The study of the mechanism of NTE essentially involves [10][11][12][13][14][15][16][17][18][19] the identification of anharmonic phonons and their softening on compression of the crystal. In thermodynamics literature a Grüneisen parameter is defines in terms of the ratio of the thermal expansion and the specific heat [20].…”