Phase relations and thermoelectric properties of alloys in the Bi2Te3-Bi2Se3 system

Using differential thermal analysis and x-ray diffraction, we have shown that the Bi2Te3-Bi2Se3 system contains a continuous series of solid solutions in a narrow temperature range and a compound of composition Bi2Te2Se below the solidus line. The liquidus and solidus lines determined using zone-melted samples differ little from those reported in the literature for equilibrium samples. The Bi2Te3−x Se x solid-solution phase extends to ∼-14 mol % Bi2Se3 (Bi2Te2.58Se0.42). The thermoelectric power of the alloys drops sharply near the boundary of the two-phase region. Within the homogeneity range of Bi2Te2Se (33.3 mol % Bi2Se3), the thermoelectric power factor has a minimum, while the thermoelectric power has a small maximum.