Synthesis, X-ray phase analysis and differential thermal analysis of nanocrystalline superionic KxCu1.85S (x<0.05) copper sulfides

Superionic semiconductor chalcogenides with mixed electronic-ionic conductivity have very low lattice thermal and are excellent thermoelectrics. Doping other elements is one of the methods for optimizing useful properties a material. In this work, nanosized polycrystalline alloys nonstoichiometric Cu1.85S copper sulfide content potassium studied. The paper presents results X-ray phase analysis, differential analysis (DTA) electron microscopy KxCu1.85S alloys. resulting mixture phases, in which main share djurleite - non-stoichiometric composition Cu1.97÷1.93S , addition, depending on alloy, there impurities monoclinic hexagonal chalcocite Cu2S roxbyite Cu1.81S anilite Cu1.75S traces metallic copper. All contain inclusions Cu2O oxide. DTA detected superionic transition from an ordered low-symmetry to disordered at about 373-383 K. revealed two effects 433 K 460 K, absent binary sulfide. reason may be redistribution impurity ions lattice.