Phase diagrams of the pseudo-binary Cu2SeBi2Se3 and Ag2SeBi2Se3 systems and thermoelectric properties of Cu2SeBi2Se3 solid solution

Abstract

The phase diagrams of the pseudo-binary systems Cu₂SeBi₂Se₃ and Ag₂SeBi₂Se₃ were determined by thermal analysis. The Cu₂SeBi₂Se₃ system has complete solid solution over all compositions, and a minimum melting point at about 33 mol. % Bi₂Se₃. The phase diagram of the Ag₂SeBi₂Se₃ system is composed of two eutectic phases and one congruently melting intermediate compound at the middle of the system. Thermoelectric figure of merit of Cu₂SeBi₂Se₃ solid solution was determined as a function of composition, and maximum thermoelectric figure of merit in this system is expected as z_max = 0·43 × 10⁻³ deg⁻¹ at 90 mol. % Bi₂Se₃.