Crystal growth and spectral studies of nonlinear optical gamma-glycine single crystal grown from phosphoric acid.

Single crystals of the organic nonlinear material gamma-glycine have been grown in the presence of phosphoric acid by slow-evaporation method. The crystal structure is confirmed by X-ray powder diffraction method. The thermal stability and decomposition of the sample have been studied by thermal analysis. The result shows that the transition temperature, i.e. transition from gamma- to alpha-glycine is enhanced from 165 degrees C to 191 degrees C. The modes of vibrations of different molecular groups present in glycine have been identified by spectral analyses. The transmittance spectrum of gamma-glycine crystal shows that the lower UV cut-off wavelength lies at 230nm. Second harmonic generation (SHG) conversion efficiency has been estimated as 125mV and the output power by the crystal was 1.3 times that of potassium dihydrogen phosphate (KDP) crystal. The dielectric and microhardness measurements have been carried out on the gamma-glycine crystal.