Solid-Phase Equilibrium Diagram of the Bi2Te3-Rich Corner of MnTe–Bi2Te3–Te System and Thermodynamic Properties of the Intermediate Phases

Abstract

In this study, the thermodynamic properties of the Bi₂Te₃-rich manganese-bismuth tellurides were determined using an electromotive force (EMF) method with a liquid electrolyte in a 300–450 K temperature interval. Solid-phase equilibrium diagram of the Bi₂Te₃-rich corner of the MnTe–Bi₂Te₃–Te system at 300 K was constructed using literature data and X-ray diffraction (XRD) analysis of synthesized electrode alloys. Functions \(\Delta \bar {Z}_{{{\text{Mn}}}}^{'}\) (\(\Delta \bar {G}_{{{\text{Mn}}}}^{'},\) \(\Delta \bar {H}_{{{\text{Mn}}}}^{'}\), and \(\Delta \bar {S}_{{{\text{Mn}}}}^{'}\)) corresponding to linear equations were calculated for different phase regions using EMF values. The relative partial molar functions of manganese in alloys were calculated with the help of these data along with the corresponding thermodynamic functions of MnTe and Bi₂Te₃. The standard thermodynamic functions of formation and standard entropies of the Bi₂Te₃-rich manganese bismuth tellurides – MnBi₈Te₁₃, MnBi₁₀Te₁₆, MnBi₁₂Te₁₉, and MnBi₁₄Te₂₂ compounds, and solid solutions based on Bi₂Te₃ have been obtained.