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^{1}Institute of Physics of Dagestan Scientific Center of RAS, Russia

**Keywords:** high pressure**property:** thermal conductivity**material:** As_{2}(Se_{1-x}Te_{x})_{3} solid solutions

Investigation of the pressure effect on the thermal conductivity of semiconductors is of interest because the knowledge of the regularities of the thermal conductivity changes under pressure is important for studying the phonons energy spectrum and defects in crystal lattices. This work presents the results of the study of the thermal conductivity pressure dependence of the series of solid solutions based on the As_{2}(Se_{1-x}Te_{x})_{3} system in the glassy and crystalline states at values of x: 0, 0.4, 0.5, 0.6, 1. Investigations of thermal conductivity were performed on a setup realizing the absolute compensation method in a stationary thermal conditions under hydrostatic pressures ranging from ambient to 0.35 GPa [1].

The studies of the pressure dependences of thermal conductivity of As_{2}(Se_{1-x}Te_{x})_{3} solid solutions showed that hydrostatic pressure leads to an increase in thermal conductivity in polycrystalline and glassy samples. In polycrystalline samples of this system the thermal conductivity increases on the 15-20% with increasing pressure up to 0.35 GPa. In these samples the thermal conductivity pressure dependence is nonlinear. The pressure dependence of the thermal conductivity in polycrystalline samples of the solid solutions due mainly to changes in phonon mean free path as a result of changes of their scattering by phonons (U-processes). Under hydrostatic pressure and decreasing volume of the crystal there is an increase of interatomic forces, the change in frequency and decrease in the anharmonicity of lattice vibrations. All this leads to an increase in thermal conductivity. Also the thermal conductivity of crystals under pressure increases due to the reduction of phonon-phonon scattering probability due to the increase of the energy gap between acoustic and optical phonons with increasing pressure. In all the studied chalcogenide glasses linear increase in thermal conductivity by an average of 10-12% is observed with increasing pressure up to 0.35 GPa. In glasses the mean free path is limited to non-periodic lattice and the structure defects, and the effect of U-processes on it is insignificant. Due to the infinitesimally of the contribution of U-processes to the heat resistance of the glasses, the effect of the hydrostatic pressure on their thermal conductivity is weaker than in polycrystals.

- Sh.M. Ismailov, Ya.B. Magomedov, N.L. Kramynina, High Temp.–High Press. V. 26, N 2. (1994), Р. 657.

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