Effect of solvents on the growth morphology and physical characteristics of nonlinear optical γ-glycine crystals

Bulk crystals of gamma-glycine have been grown at ambient temperature by solvent evaporation from a mixture of water-sodium salt as a solvent. The chemical composition of the grown crystal was determined by NMR and laser Raman spectra. The morphology of the crystals grown from various solvents showed a marked difference. The temperature of transition from gamma- to alpha-phase was determined using differential scanning calorimetry. It was observed that all the crystals except the one grown from a mixture of water and sodium hydroxide change from gamma- to alpha-phase at 168degreesC. The transition temperature of the glycine crystal grown from the mixture of glycine and sodium hydroxide was 172degreesC and the transition takes place at a lower rate. The microhardness of the crystals grown from various solvents was determined. It was found that the crystals grown from various solvents had the same hardness number. The second harmonic conversion efficiency of the grown crystals was measured relative to potassium dihydrogen phospahte. It was observed that the conversion efficiency of the crystals grown from various solvents vary slightly. (C) 2002 Published by Elsevier Science B.V.