LiGaGe2S6: A Chalcogenide with Good Infrared Nonlinear Optical Performance and Low Melting Point.

In this work, we design and synthesize a new chalcogenide LiGaGe2S6 on the basis of known infrared (IR) material LiGaS2 by partially substituting Ga with Ge. This compound possesses very strong nonlinear (NLO) response (2.5 × LiGaS2) and large band gap (3.52 eV), manifesting a better balance between band gap and NLO response compared with that for LiGaS2. Moreover, LiGaGe2S6 exhibits a much lower melting point (663 °C) than that of LiGaS2 (1050 °C). This would result in the much smaller vapor pressure of sulfur in the fused quartz vessels used for the crystal growth, and thus, it should be greatly beneficial to obtain the large stoichiometric LiGaGe2S6 single crystal. Our studies demonstrate that LiGaGe2S6 is a good candidate material for IR NLO applications.