The Effect of Phonon Anharmonicity on the Thermodynamic Properties of Nonmetallic Solid

Abstract

Germanium is used as an example for developing a self-consistent thermodynamic approach to the construction of a model of crystal lattice of a nonmetallic nonmagnetic solid. This approach takes into account the effect of anharmonicity of thermally excited phonons. The calculations of temperature dependences of basic thermodynamic functions reveal, for a model substance, very adequate agreement with the available experimental data in a wide temperature range of hundreds of kelvins.

Phonon anharmonicity of iron monosilicide

“…[15,16]. Since in the present study a compound is considered, one has to build a generalization of this model to the case of several different atoms in the unit cell.…”

“…where ℏ, N A are Plank and Avogadro constants, respectively; Ξ(σ) is a function of the Poisson coefficient σ (see [16] for reference); μ 0 is the effective molar mass, which is responsible for mass of the vibrating atoms. Since here we consider effective Debye modes, for the value of μ 0 , following [18], we take the averaged molar mass, i.e.…”