Synthesis and Properties of Synthetic Aikinite PbCuBiS3

Abstract

The goal of this study was the synthesis and study of the properties of synthetic aikinite, PbCuBiS3. The synthesis was carried out in evacuated quartz ampoules for 7–8 h; the maximum temperature was 1250–1325 K. Next, the samples were cooled and kept at 600 K for a week. Then the ampoules were opened, the samples were carefully ground, and after melting, annealed at 600–800 K, depending on the composition, for at least two weeks to bring the samples into equilibrium. The annealed samples were studied by differential thermal (DTA), X-ray diffraction (XRD), microstructural (MSA) analyses, as well as microhardness measurements and density determination. XRD was performed using D 2 PHASER with CuKa radiation and a Ni fi lter. CuBiS2–PbS, Cu2S–PbCuBiS3, Bi2S3–PbCuBiS3, PbBi2S4–PbCuBiS3, PbBi4S7–PbCuBiS3 sections of quasi-triple system Cu2S–Bi2S3–PbS were studied using the complex of physical and chemical analysis methods and their phase diagrams were plotted. It was found that in addition to the PbBi2S4–PbCuBiS3 section, all sections are quasi-binary and they were characterized by the presence of limited solubility regions based on the initial components. The study of the CuBiS2-PbS section revealed the formation of a quaternary compound PbCuBiS3 occurring in nature as the mineral aikinite, congruently melting at 980 K. We established that PbCuBiS3 crystallizes in a rhombic syngony with lattice parameters a = 1.1632, b = 1.166, c = 0.401 nm, Pnma space group, Z = 4. Using DTA and XRD methods we established that PbCuBiS3 compound is a phase of variable composition with a homogeneity range from 45 to 52 mol%/PbS. The PbCuBiS3 compound is a p-type semiconductor with a band gap energy of ΔE = 0.84 eV.

Keywords

• aikinite
• compound
• single crystal
• structure
• thermodynamic function