THERMAL CONDUCTIVITY AND THERMOELECTRIC FIGURE OF MERIT OF CUIN5S8-CDIN2S4 SOLID SOLUTIONS

Abstract

This article is devoted to the studies of the dependence between the thermal conductivity coefficient and thermoelectric figure of merit in CuIn5S8-CdIn2S4 single crystals with a content of 0, 20, 40, 60, 80 and 100 mol.% CdIn2S4 on their composition. The purpose of the work is to investigate the thermal conductivity coefficient and thermoelectric figure of merit of CuIn5S8- CdIn2S4 solid solutions. We found that the lattice component provides the main contribution to the thermal conductivity of CuIn5S8-CdIn2S4 crystals. The thermoelectric figure of merit of CuIn5S8-CdIn2S4 solid solutions was calculated. The dependence of these parameters on the CuIn5S8-CdIn2S4 component composition was analyzed. To determine the thermal conductivity coefficient, repeatedly tested equipment were used. The research was conducted at T≈300 K. An increase in the content of CdIn2S4 in the CuIn5S8-CdIn2S4 solid solution leads to an increase in the thermoelectric figure of merit of the solid solutions. The growth of the thermal conductivity coefficient for CuIn5S8-CdIn2S4 single crystals with a content of ≈20-80 mol.% CdIn2S4 can be caused by the growth of defects in the crystal lattice of single crystals. The thermoelectric figure of merit was the highest in CdIn2S4 single crystals (ZT≈0,046). The lowest values of thermoelectric figure of merit are characteristic of compounds СuIn5S8 and СuIn5S8-CdIn2S4 with ≈40 mol.% CdIn2S4 (ZT≈0,02). It is shown that by changing the component composition of CuIn5S8-CdIn2S4, it is possible to change the value of the thermal conductivity coefficient and thermoelectric figure of merit. The smooth change of thermal conductivity coefficient and thermoelectric figure of merit СuIn5S8-CdIn2S4 with a formation in the content of Cd atoms can find practical use in semiconductor instrumentation, where СuIn5S8 and CdIn2S4 materials are used.