Growth of gamma glycine crystal and its characterisation

Single crystal of gamma-glycine, an organic nonlinear optical material, has been grown by solvent evaporation technique from a mixture of aqueous solutions of glycine and potassium nitrate, lithium nitrate at room temperature. Gamma glycine crystals have been grown up to the dimension of 20mmx15mmx12mm. Powder X-ray diffraction of the grown crystal was recorded and indexed. Single crystal X-ray diffraction studies were carried out and the unit cell parameters were compared with the literature values. The gamma-phase of glycine is confirmed by single crystal XRD and FTIR spectral analysis. The crystals were characterised by UV-vis-NIR transmission spectrum in the range 200-1100nm. The second harmonic generation conversion efficiency of gamma-glycine crystal was twice the efficiency of KDP crystal. Thermal characteristics of gamma-glycine crystals were determined by thermogravimetric analysis (TGA) and differential thermal analysis, which shows the thermal stability of the grown crystals. Dielectric constant and dielectric loss measurements were carried out at different temperatures and frequencies. The microhardness of the grown crystals has been studied using Vicker's microhardness tester.