Thermal conductivity of Cu2Se taking into account the influence of mobile copper ions

LP Bulat and AA Ivanov and VB Osvenskii and DA Pshenay-Severin and AI Sorokin, PHYSICS OF THE SOLID STATE, 59, 2097-2102 (2017).

DOI: 10.1134/S1063783417100080

The temperature dependence of the thermal conductivity of nanostructured samples of copper selenide prepared by mechanochemical synthesis from initial pure components in a planetary ball mill followed by spark plasma sintering has been studied. The thermal conductivity of nanostructured samples was measured in the temperature range 410-860 K. At 410-780 K, the thermal lattice conductivity kappa(ph) varies insignificantly in the range 0.35-0.37 W/(m K). At a higher temperature T > 780 K, kappa ph decreases to 0.19 W/(m K). To analyze the influence of mobile copper ions on the thermal conductivity of the lattice, molecular-dynamic calculations were performed using a classical interatomic potential obtained from ab initio calculations for the cubic beta-Cu2Se modification. The simulation results demonstrate a high mobility of copper ions, and the calculated temperature dependence of the lattice thermal conductivity agrees with the experiment to 780 K. At a temperature T > 780 K, kappa(ph) deviates from the calculation results, and this deviation is most pronounced in the nanostructured material. As a result, at the maximum measurement temperature, the lattice thermal conductivity decreased to similar to 0.19 W/(m K), which agrees with available data for nanostructured Cu2Se samples produced by various methods.

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