Structural study of (GeTe)_1-x((Ag₂Te)_0.5333(Bi₂Te₃)_0.4667)_xsolid solutions

Abstract

The reversible cubicrhombohedral (0: bC:,) phase transition of GeTe-rich ),-,[(Ag,Te),,,s,,,(Bi2Te~)"raai]i solid solutions is studied by means of high-temperature x-ray analysis. The temperature and composition changes of the rhombohedral lattice parameten are found. They prove the displacive nature of the solid solution phase transition. Withan increasingamount ofheterovalent Agand Bi atoms replacingGecations, the phase transition temperature T, decreases. (GeTe

Phase transitions of p-type (Pb,Sn,Ge)Te-based alloys for thermoelectric applications

“…are discontinuous at a second-order phase transition point [7]. Continuous variations in the lattice parameters, underlining the second-order character of the phase transition, were observed for Pb 1Àx Ge x Te [6,8], Sn 1Àx Ge x Te [9] and (GeTe) 1Àx [(Ag 2 Te) y (Bi 2 Te 3 ) 1Ày ] x [10,11] by means of high temperature X-ray diffraction (XRD) measurements. For the latter alloys, the experimental evidence for a second-order phase transition was also supported theoretically, by applying the Landau-Lifshitz type of symmetry criterion [10,11].…”