Synthesis, Growth, and Characterization of Bisglycine Hydrobromide Single Crystal

Single crystals of BGHB were grown by slow evaporation technique. The unit cell dimensions and space group of the grown crystals were confirmed by single crystal X-ray diffraction. The modes of vibration of the molecules and the presence of functional groups were identified using FTIR technique. The microhardness study shows that the Vickers hardness number of the crystal increases with the increase in applied load. The optical properties of the crystals were determined using UV-Visible spectroscopy. The thermal properties of the grown crystal were also determined. The refractive index was determined as 1.396 using Brewster’s angle method. The emission of green light on passing the Nd: YAG laser light confirmed the second harmonic generation property of the crystals and the SHG efficiency of the crystals was found to be higher than that of KDP. The dielectric constant and dielectric loss measurements were carried out for different temperatures and frequencies. The ac conductivity study of the crystals was also discussed. The photoconductivity studies confirm that the grown crystal has negative photoconductivity nature. The etching studies were carried out to study the formation of etch pits. 1. Introduction Nonlinear optical (NLO) applications demand good quality single crystals, which inherit large NLO coefficient, coupled with improved physical parameters. One potentially attractive system, where there is a potential for realizing very large second order nonlinear coefficient is based on organic crystals. Organic materials have been of particular interest because the nonlinear optical responses in this broad class of materials is microscopic in origin, offering an opportunity to use theoretical modeling coupled with synthetic flexibility to design and produce novel materials [1]. Further investigations on organic NLO materials have subsequently produced very good materials with highly attractive characteristics. Amino acid family crystals have been subjected to extensive investigation during the recent decades for their nonlinear optical properties [2]. In the present day technological society, nonlinear optical (NLO) materials are most useful in the area of optical data storage, lasers, optical signal processing, second harmonic generation, and so forth. Even though varieties of nonlinear optical materials are available, their applications are limited due to physical and chemical properties [3]. Amino acids are interesting materials for NLO applications as they contain a proton donor carboxyl acid (COOH) group and the proton acceptor amino (NH2)