Synthesis and study the structure, optical, thermal and dielectric properties of promising Glycine Copper Nitrate (GCN) single crystals

Four novel single crystals of α-glycine and γ-glycine doped by copper nitrate: (Glycine)1−X (Cu(NO3)2·3H2O)X abbreviated as (GCN1, GCN2, GCN3, GCN4) were prepared from aqueous solution by the slow evaporation method. Four doping concentrations: x = 0.005, 0.01, 0.02 and 0.04 of hydrated copper nitrate were used. The crystals were studied using powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV-Vis spectroscopy. The PXRD patterns showed that crystals containing high concentration of Cu(NO3)2·3H2O have triclinic or monoclinic structure. The lattice parameters for all the prepared crystals were found to be in a good agreement with that found in the crystallographic open database (COD). The functional groups of the crystals were determined from FTIR spectra and the optical band gaps were calculated from UV-Vis spectroscopy technique. The properties of the crystals was found to be concentration dependent on copper nitrate salt. The refractive index (n) for all GCN crystals were found around 1.88 in the region of the wavelength: 800-1000 nm, while the least value of n ≈ 1.72 was determined in the visible region of electromagnetic magnetic radiation. The decomposition point of GCN single crystals was identified by a narrow, and sharp peak of differential scanning calorimetry (DSC) curves. The phase transition temperature at 203 °C was observed for GCN2 crystals, is probably due to the transformation from γ-glycine to α-glycine. The dielectric study showed a peak around 30 °C (Curie temperature) that is a characteristic of ferroelectric crystals and the consistency of the dielectric constant at 90 °C indicated glass transition. Photoluminescence spectra of GCN crystals that were recorded at the excitation wavelength of 280 nm showed a maximum emission peaks around 345 nm. This finding indicated that these single crystals can be successfully used for NLO applications.