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 K0.01Cu1.96S , K0.02Cu1.95S , K0.03Cu1.94S , K0.04Cu1.93S , K0.05Cu1.94S 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 K0.01Cu1.96S is a mixture of phases consisting of chalcocite Cu2S (82%), jarleite Cu1.96S (12%), anilite Cu1.75S (6%). The composition of samples K0.02Cu1.95S and K0.03Cu1.94S includes the most common phases of copper sulfides - chalcocite Cu2S , jarleite Cu1.96S , digenite Cu1.80S . Samples K0.04Cu1.93S and K0.05Cu1.94S consist of jarleite Cu1.96S , digenite Cu1.80S 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 K0.02Cu1.95S and K0.03Cu1.94S are very favorable for achieving high thermoelectric figure of merit ZT material.