Thermal analysis of (ZnTe)x(CdSe)1-x crystals

摘要

Powders prepared from vapor phase grown single crystals of (ZnTe)$-x$/(CdSe)$- 1$MIN@x$/ in the entire range of x were subjected to differential thermal and thermo gravimetric studies in the temperature range 300 - 1110 K in air atmosphere. The general decrease observed in differential temperature is attributed to vaporization of constituents as II -VI compounds and their alloys evaporate rapidly well below their melting points. Some exothermic peaks were also observed at different temperatures. In samples of all compositions, a very sharp peak around 920 K was observed. All the exothermic peaks in DTA curves showed corresponding effects in TG cures. This shown that the peaks are not associated with phase changes reported in similar other II -VI quaternary namely (ZnSe)$-x$/(CdTe)$- 1$MIN@x$/ crystals. The heats of reaction did not show any regular variation with composition. The TG peaks are attributed to stable oxidation states of Zn/Cd whereas the dips could be due to the formation of unstable oxides of chalcogens. The rates of reaction/evaporation showed that the vaporization phenomenon dominates over the oxidation processes in samples with x $LSEQ 0.5. This is in conformity with the observed lower growth rates of crystals with x $GRT 0.5.