EFFECT OF DYSPROSIUM DOPING ON MICROSTRUCTURE AND DEGREE OF TEXTURING OF BISMUTH TELLURIDE-BASED THERMOELECTRIC MATERIALS

The purpose of this work was to prepare and identify the features of the microstructure and the degree of texturing of the thermoelectric material Bi2Te2.7Se0.3 doped with dysprosium. Textured Bi2-xDyxTe2.7Se0.3 compounds with x = 0.0000; 0.0010; 0.0025; 0.0050; 0.0100 and 0.0200 were prepared by using solvothermal synthesis and spark plasma sintering of starting powders. Dy-doping results in several interconnected effects. First of them is reducing in size of particles in starting powders with increasing x. This effect is attributed to increasing in ionic bonding fraction in polar covalent Bi(Dy)–Te bonds with increasing Dy content due to difference in electronegativity of Bi and Dy. With increasing x, grain size in bulk samples is also reducing, which is governed by relevant changing in the size of particles in the starting powders with different dopant content. This effect also results in enhancing in texturing degree in samples.