Temperature dependence of the band gap of MnAgIn$_{7}$S$_{12}$ single crystals

MnAgIn$_{7}$S$_{12}$ single crystals 16 mm in diameter and $\sim$40 mm in length are grown by planar crystallization of the melt. It is shown that the material grown crystallizes with the formation of the cubic spinel structure. From the transmittance spectra recorded in the region of fundamental absorption in the temperature range 10–320 K, the band gap $E_g$ of the single crystals and its temperature dependence are determined. The dependence has a shape typical of most semiconductor materials: as the temperature is lowered, the band gap $E_g$ increases. A calculation is carried out, and it is shown that the calculated values are in agreement with the experimental data.