Thermal conductivity and balanced performance in infrared nonlinear optical multicomponent chalcogenides LixAg1−xGayIn1−ySe2

Abstract

The performance of infrared (IR) nonlinear optical (NLO) materials is significantly affected by the thermal conductivity k_L, but studies on the structure and property relationship of k_L in these materials are very rare. In this work we evaluated the k_L in IR NLO multicomponent chalcogenides Li_xAg_1−xGa_yIn_1−ySe₂ with a smooth change in the compositions x and y by using a machine learning approach and laser flash measurements, combined with available experimental results. The found patterns of k_L dependence on the atomic mass, bond length and electronegativity provide an effective understanding for navigation in the process of searching for new chalcogenide crystals with an optimal set of parameters that allow them to be effectively used as a frequency converter of laser radiation in the IR range. Moreover, the compositions Li_0.5Ag_0.5GaSe₂, Li_0.81Ag_0.19InSe₂ and AgGa_0.5In_0.5Se₂ are demonstrated to exhibit a balanced combination of the parameters k_L, NLO effects, energy band gaps, and birefringence for IR NLO applications.