Phase equilibria in Cd0.80Mn0.20Te solid solutions

Abstract

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.