Optical and thermal properties of CuAlxIn1−xTe2 solid solutions

The optical and thermal properties of crystals of CuAlxIn1−xTe2 solid solutions grown by the Bridgman-Stockbarger method were studied for the first time. From the transmission and reflection spectra in the region of the intrinsic-absorption edge, the band gap (Eg) was determined for the CuInTe2 and CuAlTe2 compounds and for their solid solutions; the concentration dependence of Eg was plotted. The Eg value was found to vary nonlinearly with x and can be described by the quadratic dependence. Dilatometry was used to study the thermal expansion of these solid solutions. The coefficient of thermal expansion (αL) was shown to have a λ-shaped temperature dependence in the region of phase transitions. The isotherms are plotted for the concentration dependence of αL. The thermal conductivity was investigated and its concentration dependence was plotted. The dependence of the thermal conductivity on x was established to have a minimum in the region of medium compositions.