Phase equilibriums and thermodynamic properties of the system Bi–Te–I

Abstract

The system Bi–Te–I was studied by methods of differential thermal analysis and the X-ray diffraction, and also by measurements of electromotive forces (EMF) of concentration chains of type (−) Bi (s) | liquid electrolytic conductor, Bi 3+ | (Bi–Te–I) (s) (+) in the temperatures range of 300–400 K. The series of polythermal sections and isothermal section of the phase diagram at 300 K, and a projection of the liquidus surface were constructed. Earlier indicated ternary compounds BiTeI, Bi 2TeI and Bi 4TeI 1.25 were confirmed, the position of phase areas and their relationships was established. Areas of primary crystallization fields, types and coordinates of the non- and mono-variant equilibriums were determined. The measurements of EMF have allowed calculation of partial molar functions ( Δ G ¯ , Δ H ¯ , Δ S ¯ ) of bismuth in alloys, standard thermodynamic functions of formation and standard entropies of the indicated ternary compounds.