Thermoelectric properties of Bi$_{2-x}$Lu$_{x}$Te$_{2.7}$Se$_{0.3}$ solid solutions

The thermoelectric properties of compounds based on Bi$_{2-x}$Lu$_{x}$Te$_{2.7}$Se$_{0.3}$ solid solutions with $x$ = 0, 0.05, 0.1, and 0.2 are studied. The samples for investigations are prepared by chemical-solution deposition (to synthesize the initial powders) and spark plasma sintering (to obtain bulk samples). The patterns of changes in the electrical resistivity, Seebeck coefficient, and total thermal conductivity of the samples are determined as a function of the lutetium content. It is established that the optimal combination of these thermoelectric characteristics is attained for the composition with $x$ = 0.05, which demonstrates the highest thermoelectric figure of merit ($ZT\approx$ 0.9 in the temperature range of 400–480 K) among all the studied compositions.