Abstract
N-type-(Bi2Se3)x(Bi2Te3)1-x alloys have good thermoelectric properties. Recent studies indicate the thermoelectric properties of the (Bi2Se3)x(Bi2Te3)1-x alloys can be further enhanced with In doping. Quaternary Bi-Te-Se-In alloys with 40at.%Bi are prepared and equilibrated at 250oC. The phase equilibria isoplethal section of the Bi-Te-Se-In quaternary system at 40at%Bi is constructed based on the available phase equilibria information of the constituent binary systems, constituent ternary systems, related quaternary system, and most importantly the experimental data of this study. There are seven phase regions along the Bi0.4-(Te-In)0.6 side: L, L+In4Te3, L+In4Te3+InTe, L+InTe, Bi+InTe+L, Bi+InTe and Bi+InTe+Bi7Te3. There is a miscibility gap at the Bi2Se3 and Bi2Te3 isoplethal section, and there are three phase regions, Bi2Se3, Bi2Se3+Bi2Te3 and Bi2Te3, along the Bi0.4-(Te-Se)0.6 side. Along the Bi0.4-(Se-In)0.6 side, there are twelve phase regions, including L, L+InSe, Bi+L+InSe, Bi+InSe, Bi+InSe+In6Se7, Bi+In6Se7, Bi+In6Se7+In2Se3, Bi+In2Se3, Bi+In2Se3+BiSe, BiSe+In2Se3, BiSe+In2Se3+Bi2Se3 and Bi2Se3. No quaternary compound is found in this study.