Thermal conductivity of new nanocomposite superionic semiconductors K0.01Cu1.96S, K0.02Cu1.95S, K0.03Cu1.94S, K0.04Cu1.93S, K0.05Cu1.94S

Abstract

In this work, we investigated the effect of nanostructuring on the thermoelectric and thermal properties of nonstoichiometric solid splavs doped with copper sulfides with potassium. The synthesized alloys K_0.01Cu_1.96S, K_0.02Cu_1.95S, K_0.03Cu_1.94S, K_0.04Cu_1.93S, K_0.05Cu_1.94S are nanocomposite. The crystallite sizes of the synthesized powder, as estimated from the half-width of X-ray diffraction lines, range from 7 to 180 nm. Sample K_0.01Cu_1.96S is a mixture of phases consisting of chalcocite Cu₂S (82%), jarleite Cu_1.96S (12%), anilite Cu_1.75S (6%). The composition of samples K_0.02Cu_1.95S and K_0.03Cu_1.94S includes the most common phases of copper sulfides - chalcocite Cu₂S , jarleite Cu_1.96S, digenite Cu_1.80S. Samples K_0.04Cu_1.93S and K_0.05Cu_1.94S consist of jarleite Cu_1.96S, digenite Cu_1.80S and potassium copper sulfide KCu₄S₃ phases. In a practical sense, the extremely low thermal conductivity values (from 0.16 to 0.80 W/m · K) found in the range of 300–700 K for nanocomposite samples K_0.02Cu_1.95S and K_0.03Cu_1.94S are very favorable for achieving high thermoelectric figure of merit ZT material.