Growth and characterization of nonlinear optical crystal Gamma glycine by the additive of lithium bromide

Abstract

Single crystal of γ-glycine, a polymorphic form of glycine, was grown by slow solvent evaporation technique by the additive of lithium bromide. It was grown from the aqueous solution of glycine and lithium bromide in 2:1 M ratio respectively at room temperature. Good quality of γ-glycine single crystals was harvested up to the dimension of 25 × 22 × 20 mm3. In order to reveal its properties, the grown single crystals were subjected to various characterizations. Powder X-ray diffraction of the grown crystal was recorded and indexed. The unit cell parameters of the crystals were estimated by single crystal x-ray diffraction and they were compared with the literature values. The identification of the functional groups and hence the compound present in the crystalline sample by FTIR analysis confirms the polymorphic form of glycine. Optical transmittance studies were carried out by UV–Vis-NIR transmission spectrum in the range of 200–1100 nm wavelength. The powdered sample of the crystal was subjected to Kurtz Perry powder technique to find the coefficient of Second harmonic generation. The second harmonic generation (SHG) conversion efficiency of γ-glycine crystal is more than twice when compared with KDP crystal. The grown γ-glycine crystal was further characterized by Thermo gravimetric analysis (TGA) and Differential thermal analysis, to find its thermal stability and decomposition temperature. Dielectric constant and Dielectric loss were determined at different frequencies with respect to various temperatures. The mechanical properties such as microhardness and yield strength were evaluated by Vicker’s microhardness tester.