LiGaTe2 (LGT) nonlinear crystal: Synthesis and crystal growth processes exploration

Abstract

The LiGaTe2 (LGT) single crystal up to 12mm in size was grown in 3 stages: synthesis, homogenization and crystal growth. The initial charge with 6–10at% excess of Li2Te was produced by melting elementary Li, Ga and Te components. The homogenization step was carried out with the maximum value of melt overheating not exceeding 50K. The Bridgman-Stockbarger technique was used to grow the LiGaTe2 crystals. A furnace of special design, providing the enlargement of LGT linear size, was used. At each stage (synthesis, homogenization and crystal growth) the DTA analysis was carried out: during heating and cooling we recorded peaks corresponding to melting or crystallization of different components in the charge, such as Te0 (melting point 739K) and LiGaTe2 (melting point 945K) and in the as-grown crystal. The XRD analysis was also carried out at each technological stage. The analysis showed that there are 2 side phases (Te0, Ga2Te3), and their phase contents decrease to 1.2at%, while the LiGaTe2 phase increases up to 93.5at% during the homogenization process. The synthesized charge composition was analyzed by flame photometry (for Li) and atomic absorption (for Ga and Te). To provide a flat crystallization front and optimal conditions for crystal growth, spatial distribution of thermal field in the furnace was simulated. Transmission spectrum was recorded for the as-grown LGT crystal.