The kinetic parameters of melting and crystallization of Cd0.85-xMnxZn0.15Te (x = 0.05-0.20) alloys were investigated by the differential thermal analysis (DTA) method at different heating/cooling rates. Cd0.85-xMnxZn0.15Te alloys were synthesized from elementary materials in a vertical furnace with a high-gradient temperature that prevented the sublimation of the components. The DTA was carried out in an automatic system. The heating and cooling rates were 5 and 10°С/min, and the dwell time was 10, 30 and 60 minutes. The DTA were processed in two different ways. Using the first treatment method we found that the melt of the Cd0.80Mn0.05Zn0.15Te alloy crystallize with the supercooling, and it occurs at melt superheating higher than 12 °С. But the melt’s “negative” supercooling effect is present for alloy when the melt are superheated to 12 °C compared to the melting temperature of the alloy, which is evidence of two-phase alloy (solid phase - melt) at these temperatures. Also we determined that as the holding temperature increases the crystallization temperature decreases and the crystallization rate increases. We investigated that the area of the crystallization effect increases with increasing holding temperature. Concerning on the second treatment method we found the dependence of the solid-state volume fraction (φsolid state) versus the intermediate dwell temperature of the alloy during the heating process for Cd0.80Mn0.05Zn0.15Te. It shows that increasing of the melt-dwell temperature led to the melts full homogenization only near 1117 °C. Thus according to our previous researches we can say that the Cd1-x-уMnxZnyTe alloy’s melting temperature increases with ZnTe concentration increasing: ~1100-1102°С for Cd0.95-xMnxZn0.05Te alloys (x=0.05-0.30), ~1102-1104°С for Cd0.90-xMnxZn0.10Te alloys (x=0.05-0.30) and ~1116-1119°С for Cd0.80Mn0.05Zn0.15Te alloys.
The thermal properties of Cd0.80Mn0.20Te solid solutions were investigated in this article. Two methods of heat treatment were used for thermography of alloys, which allowed investigating their thermal properties. One of the methods of thermography of samples was to heat them to the maximum temperature at which they were kept for a certain time, followed by cooling of the sample. The data obtained by this type of thermography allow obtaining graphs which characterized the crystallization parameters of the melt Cd0.80Mn0.20Te. It is shown that the crystallization of the Cd0.80Mn0.20Te melt occurs without supercooling at its overheating less than 14 °С in comparison with the beginning of melting temperature, which indicates the two-phase melt. It is also shown that the crystallization rate of the Cd0.80Mn0.20Te melt increases with decreasing crystallization temperature. Thermography of alloys by the second method of heat treatment is to conduct a series of isothermal holding during heating of the samples to the maximum temperature (1150 °C). Thus, the parameters of alloy melting were investigated. It was determined that the volume fraction of solid phase in the Cd0.80Mn0.20Te melt decreases from 100% to 0% in the temperature range 1078-1095 °С. Based on the obtained data of differential thermal analyses the Cd0.80Mn0.20Te ingot was grown under controlled conditions. After cutting this crystal we can see several monocrystalline areas of different sizes. IR microscope showed that the minimum number of inclusions <7 mm in diameter distributed in different parts of the sample The value of the band gap in all samples ranges from 1.78 to 1.80 eV. The value of the resistivity of the crystal Cd0.80Mn0.20Te is 2•107 Ohm • cm at the beginning of the ingot and decreases by 2 orders of magnitude by the end of the ingot.
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