Structural, optical, second harmonic, and mechanical studies on zinc chloride added alpha-glycine crystals

The slow evaporation solution method was employed to synthesize and crystallize zinc chloride doped α-glycine (ZCAG) single crystals. The single crystal X-ray diffraction studies of pure α-glycine single crystals revealed that the structure belong to primitive monoclinic lattice. Powder X-ray diffraction studies of ZCAG showed the well-defined sharp peaks and formation of centrosymmetric structure with space group P21/n. The increase in lattice volume of ZCAG suggested that the access of zinc chloride into the α-glycine crystal and the entry of zinc chloride to the α-glycine crystal was also established from the energy-dispersive X-ray analysis. Fourier transform infrared spectrum of ZCAG revealed that the functional groups of α-glycine was not transformed due to the introduction of zinc chloride into the lattice. The optical transparency of ZCAG was observed in the UV–visible region, and it exhibited a superior transmittance in the visible region. Energy bandgap value was determined and found to changes while increasing the dopant concentration. An emission peak was observed in the violet region from the photoluminescence spectra. The centrosymmetric ZCAG exhibited second harmonic generation efficiency of 1.44 times higher than standard potassium dihydrogen phosphate, possibly due to local non-centrosymmetry in the lattice, which is further augmented by lattice distortion induced by the dopant. Low dielectric constant and loss of the grown ZCAG crystals showed the remarkable application of non-linear optical. The Meyer index indicates that the grown ZCAG are categorized as soft materials.