Akademik Məlumat İdarəetmə Sistemi
Kondensirovannye Sredy Mezhfaznye Granitsy, vol.23, no.1, pp.32-40, 2021 (Scopus)
The phase equilibria in the Tl2Te-TlBi?e2-TlTbTe2 concentration area of the Tl-Bi-Tb-Te quaternary system were investigated by using the differential thermal analysis and powder X-ray diffraction techniques. The diagram of the solid-phase equilibria of this system at room temperature was constructed. It was established that the Tl9BiTe6-Tl9TbTe6 section divides the Tl2Te-TlBi?e2-TlTbTe2 system into two independent subsystems. It was found that the Tl2Te-Tl9BiTe6-Tl9TbTe6 subsystem is characterized by the formation of a wide field of solid solutions with a Tl5Te3 structure (d-phase) that occupy more than 90% of the area of the concentration triangle. The results of X-ray phase analysis of alloys of the Tl9BiTe6-Tl9TbTe6-TlTbTe2-TlBi?e2 subsystem showed the formation of wide regions of solid solutions based on TlTbTe2 and TlBiTe2 along the section of TlTbTe2-TlBiTe2 ((b1- A nd b2-phases) and made it possible to determine the location of the heterogeneous phase regions in this subsystem. The parameters of crystal lattices of mutually saturated compositions of the b1-, b2-, and d-phases are calculated from powder diffraction patterns. The paper also presents some polythermal sections, isothermal sections at 740 and 780 K of the phase diagram, as well as projections of the liquidus and solidus surfaces of the Tl2Te-Tl9Bi?e6-Tl9TbTe6 subsystem. The liquidus surface consists of three fields of the primary crystallization of a (Tl2Te)-, d- A nd b1-phase. The constructed isothermal sections clearly demonstrate that the directions of the tie lines do not coincide with the T-x planes of the studied internal sections, which is characteristic of non-quasi-binary polythermal sections. The obtained new phases are of interest as potential thermoelectric and magnetic materials.