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

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 0.01 Cu 1.96 S, K 0.02 Cu 1.95 S, K 0.03 Cu 1.94 S, K 0.04 Cu 1.93 S, K 0.05 Cu 1.94 S 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 0.01 Cu 1.96 S is a mixture of phases consisting of chalcocite Cu 2 S (82%), jarleite Cu 1.96 S (12%), anilite Cu 1.75 S (6%). The composition of samples K 0.02 Cu 1.95 S and K 0.03 Cu 1.94 S includes the most common phases of copper sulfides - chalcocite Cu 2 S , jarleite Cu 1.96 S, digenite Cu 1.80 S. Samples K 0.04 Cu 1.93 S and K 0.05 Cu 1.94 S consist of jarleite Cu 1.96 S, digenite Cu 1.80 S and potassium copper sulfide KCu 4 S 3 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 0.02 Cu 1.95 S and K 0.03 Cu 1.94 S are very favorable for achieving high thermoelectric figure of merit ZT material.