Pressure-Assisted Method for the Preparations of High-Quality AaGaS2 and AgGaGeS4 Crystals for Mid-Infrared Laser Applications

Recently developed chalcogenides nonlinear optical crystals have potential application in mid- to far-infrared laser fields. However, high-quality single crystals are hard to be prepared because of high vapor pressure of sulfur component and decomposition of chalcogenides during the polycrystalline synthesis and single-crystal growth. A pressure-assisted technique was performed to prepare stoichiometric AgGaS2 and AgGaGeS4 polycrystalline materials. On the basis of the synthesized polycrystalline materials, high-quality AgGaS2 and AgGaGeS4 single crystals were successfully obtained using the seed directional Bridgman method with a well-designed crucible-capsule technique. These single crystals possess high homogeneity and low absorption coefficient, making it can be applied in nonlinear optical experiments. The pressure-assisted method can also be suitable to prepare other chalcogenide and phosphide compounds. The method of polycrystalline synthesis and single crystals growth described in this work will b...