The phase diagram of the system thallium(I) telluride – indium(III) telluride has been established for the first time by Babanly and Kuliev [1]. According to the results obtained by these authors employing differential thermal analysis, X-ray diffraction and microhardness method, Tl2Te and In2Te3 formed two terminal solid solutions on either side of the system as well as the phase TlInTe2 of variable composition within ca. 5 mole %. We re-examined the system, using another experimental method, namely concentration cell EMF measurement method.
From our results it followed that:
1. The terminal solid solution on In2Te3 side was quite narrow and covered 5 mole % only, i.e. from pure In2Te3 to 95.5 mole % In2Te3, contrary to the results reported in [1];
2. Within the region from 95.5 to 54.0 mole % In2Te3, two phases existed;
3. Tl2Te + In2Te3 mixtures of composition 52.0, 51.0, 50.0 and 49.0 mole % In2Te3 were one-phase alloys. It followed from that the E443 and dE/dT values decreased continuously within this composition range (where E443 and dE/dT are EMF and its temperature coefficient, respetively). Moreover, the linear dependence of EMF vs. temperature (E = f(T)) showed “break” at 444 K which was an indication that the alloys from the region underwent a phase transformation at this temperature;
4. The alloys of compositions 45.0 – 42.0 mole % In2Te3 and 42.0 – 29.0 mole % In2Te3 showed constant E443 and dE/dT values in each but at the same time quite different. This is an evidence for a compound formation of probable formula Tl8In6Te13. This compound has not been found earlier;
5. The other terminal solid solution on the Tl2Te side was much more wide, its existence range covered as much as 25 mole % (from pure Tl2Te to 25 mole % In2Te3).
From the presented results a conclusion may be derived that the phase diagram for the system Tl2Te – In2Te3 is to be verified.
References
[1] Babanly M.B., Kuliev A.A., Zhur. Neorg. Khim., 21, 1976, 1658.