Chalcogenides of bismuth obtained by various methods

Abstract

The microstructure and thermoelectric properties of a Bi2Te3–Bi2Se3 solid solution samples containing 20 mol. % Bi2Te3 doped with Hg2Cl2 of n-type conductivity obtained by hot pressing, extrusion and spark plasma sintering of powders prepared by melt spinning and grinding the ingot in a ball mill were studied. Optical and electron scanning microscopy methods were used. The effect of the disk rotation speed on the morphology of particles obtained by melt spinning is investigated. The Seebeck coefficient, electrical conductivity and thermal conductivity were measured at room temperature and in the temperature range 100 – 700 K and the thermoelectric figure of merit was calculated. The samples had anisotropy of electrical conductivity (σ) and thermal conductivity (κ) in the direction perpendicular and parallel to the pressing, the Seebeck coefficient (α) was isotropic. At 300 K anisotropy factors σ┴/σ// ~ 2, κ┴/κ// ~ 2, α┴/α// ~ 1. The highest thermoelectric figure of merit (ZT)max = 1,0 ± 0,1 at ~ 470 K was obtained for extruded samples from powders prepared by grinding the ingot and for hot-pressed samples from powders obtained by melt spinning.