Thermoelectric Composite of (Bi0.98In0.02)2Te2.7Se0.3/Bi2Se3 with Enhanced Thermopower and Reduced Electrical Resistivity

By using the solid-state reaction approach, composite polycrystalline samples of (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 / x %Bi 2 Se 3 were created with varying amounts of Bi 2 Se 3 , ( x = 5%, 10%, 15%, and 20%). The hexagonal crystal structure of the composite was revealed by x-ray diffraction (XRD) with a space group of R 3 ¯ m . The surface of the samples was seen to have secondary particles using a field emission scanning electronic microscope. Every sample displayed the typical semi-conducting behaviour across the entire temperature range. In the complex (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 , it was found that bismuth was coordinated with six selenium atoms and there were significant selenium vacancies. With an increase in bismuth selenide concentration, the dissolution pattern shifted to a substitutional pattern. A two fold decrease in electrical resistivity for (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 /20%Bi 2 Se 3 composition was seen compared to (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 /5%Bi 2 Se 3 . The granular material was produced by sintering and scattering of potential barrier, a thermal process that increases the Seebeck coefficient. A 200% increase was observed in thermopower for (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 /20%Bi 2 Se 3 compared to (Bi 0.98 In 0.02 ) 2 Te 2.7 Se 0.3 /5%Bi 2 Se 3 compound. Graphical Abstract