Synthesis, Structure, and Thermoelectric Properties of Holmium-Doped Nanomaterials Based on Bismuth Telluride

Powdered thermoelectric materials Bi2-xHoxTe2.7Se0.3 (x = 0, 0.001, 0.0025, 0.005, 0.01, and 0.02) are obtained by the method of solvothermal synthesis. The possibility of obtaining nanomaterials based on holmium-doped bismuth telluride is shown. The influence of the concentration of holmium on the parameters of the crystal lattice, morphology and average size of the synthesized particles are studied. Bulk materials Bi2-xHoxTe2.7Se0.3 are obtained by spark plasma sintering. All obtained samples are textured, the crystallographic axis of the texture (0 0 l) is directed parallel to the direction of the application of pressure during compaction. Development of the texture is confirmed by scanning electron microscopy and X-ray diffraction (XRD) analysis. The grains in the textured samples form an ordered lamellar structure, and the lamellar sheets lie in the plane perpendicular to the direction of pressing. An increase in the concentration of holmium leads to an increase in the degree of texturing. The thermoelectric properties of the bulk materials Bi2-xHoxTe2.7Se0.3 are also obtained