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Thermal expansion and Grüneisen parameters for anisotropic solids

1984; American Physical Society; Volume: 29; Issue: 4 Linguagem: Inglês

10.1103/physrevb.29.1741

1095-3795

C. L. Choy, S. P. Wong, K. Young,

High-pressure geophysics and materials

An improved definition of Gr\"uneisen parameters ${\stackrel{^}{\ensuremath{\gamma}}}_{\ensuremath{\mu}}$ for anisotropic solids leads to a clearer relationship with the measured thermal expansivities ${\ensuremath{\alpha}}_{\ensuremath{\mu}}$. The corresponding definition of mode Gr\"uneisen parameters ${\stackrel{^}{\ensuremath{\gamma}}}_{\ensuremath{\mu}}^{i}$ expresses the contribution of mode $i$ to ${\ensuremath{\alpha}}_{\ensuremath{\mu}}$, and these are related to the cubic coefficients in the potential-energy function. A phenomenological two-component model due to Gr\"uneisen is then revived in a simplified form and is shown to yield insight into the temperature dependence of ${\ensuremath{\alpha}}_{\ensuremath{\mu}}$. The data on tellurium are analyzed as an example.