Mechanical properties of (Bi,Sb)₂Te₃ solid solutions obtained by directional crystallization and spark plasma sintering

Abstract

We have studied the temperature dependence of the mechanical strength at uniaxial compression for solid solutions based on bismuth and antimony chalcogenides, which were prepared by three methods: (i) vertical zone melting (VZM), (ii) hot extrusion, and (iii) spark plasma sintering (SPS). In the samples of solid solutions obtained by VZM and extrusion, a brittle–ductile transition was observed in a wised temperature interval of 200–350°C. In nanostructured SPS samples, transition from brittle to plastic fracture was observed within 170–200°C. The room-temperature strength of nanostructured samples was eight to nine times as large as that of VZM samples, and the stress–strain curves of these materials were significantly different. At a temperature of about 300°C, the strength of nanostructured solid solutions decreases to nearly zero.