Investigation on growth and macro-defects of a UV nonlinear optical crystal: ZnCd(SCN)4

Large single crystals of the coordination complex nonlinear optical material zinc cadmium thiocyanate, ZnCd(SCN) 4 (abbreviated as ZCTC), were grown from aqueous solutions by the solvent evaporation method. The morphology of the crystals was indexed. The grown crystals were characterized by the powder X-ray diffraction analysis allowing to identify the diffraction planes. Six kinds of macro-defects were found in ZCTC large crystals. These defects include cracks, inclusions, negative crystals, growth striations, sector boundaries and straight pipes. The morphologies and distribution regularities of these defects were observed and analyzed using optical microscopy. Their formation mechanisms and the methods of eliminating these defects are discussed.