Synthesis, Growth and Mechanical Properties of Mid-infrared Nonlinear Optical Crystal CdGeAs2

Abstract CdGeAs2 crystal is a promising nonlinear optical material for second harmonic generation (SHG) and optical parameter oscillation (OPO) applications in mid-infrared range. In this work, CdGeAs2 polycrystalline was synthesized using temperature oscillation method and CdGeAs2 single crystals with diameters of 30 mm were grown by modified vertical Bridgeman method. The synthesized polycrystalline was characterized by X-ray diffraction (XRD). The composition and transmission of wafers cut from a single crystal were characterized by energy dispersive spectrometer (EDS) and IR Prestige-21 spectrophotometer. The mechanical properties such as Young's modulus and hardness of (001), (100), (102) and (112) faces of CdGeAs2 were measured by nanoindentation technique. The measured Young's moduli established a relationship with the bonding direction, i.e., the closer the indentation direction was to the bonding direction, the stronger the stiffness will be.