Temperature dependence of the properties of the Li0.81Ag0.19InSe2 nonlinear crystal

The factors that determine the prospects of a crystal for frequency conversion of laser radiation in a wide range to the mid and far infrared (IR) ranges are nonlinear parameters and laser damage threshold (LDT). The latter is determined by the band gap and thermophysical characteristics. This work was devoted to studying the features of the structure change of the Li0.81Ag0.19InSe2 crystal in the temperature range 90-490 K. The temperature dependences of the thermal expansion co-efficients, dispersion and optical characteristics in this range were studied. A relationship between the temperature change in the structure and other parameters has been established. In Li0.81Ag0.19InSe2 crystals, pyroluminescence was observed during heating or cooling in the range of 100-300 K, which indicates the crystal is attributed to pyroelectrics. The dispersion characteristics (nx, ny and nz) for wavelengths of 2 and 7 mu m were studied, the values of birefringence Delta n (nz -nx) were calculated in the temperature range 300-500 K. The detected fluctuations of Delta n in the temperature range from 300 to 478 K may be associated with structural changes.