Effect of magnesium chloride on growth, crystalline perfection, structural, optical, thermal and NLO behavior of γ-glycine crystals

In the present study, single crystals of γ-glycine possessing excellent non-linear optical properties were successfully grown at room temperature in the presence of magnesium chloride (MgCl2) for the first time by using the slow solvent evaporation method. The second harmonic conversion efficiency of γ-glycine crystal was determined using Kurtz powder technique with Nd:YAG laser and was found to be 6 times greater than that of the standard inorganic sample potassium dihydrogen phosphate (KDP). The crystalline perfection of the grown crystal was analyzed using high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The grown crystal was subjected to single crystal XRD and powder XRD, which confirmed that the crystal has hexagonal structure and belongs to space group P31. Inductively coupled plasma optical emission spectrometry (ICP-OES) was carried out to quantify the concentration of Mg element in the grown γ-glycine single crystal. Fourier transform infrared (FTIR) spectral studies were made to identify the functional groups. The optical band gap was likewise estimated for γ-glycine crystal using UV–vis–NIR study. The optical measurements of γ-glycine crystal helped to calculate the optical constants such as refractive index (n), the extinction coefficient (K), electric susceptibility (χc) and both the real (∈r) and imaginary (∈i) components of the dielectric permittivity functions of photon energy, which is essentially required to develop optoelectronic devices. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study thermal stability and decomposition point of the grown crystal.