A systematic approach to physico-chemical analysis of tris (thiourea) zinc selenate - A semi-organic nonlinear optical crystal

Semi-organic single crystals of pure tris (thiourea) zinc selenate (TTZS) were grown from aqueous solution by slow evaporation method. X-ray diffraction studies inferred the orthorhombic nature and Pca21 space group of the title crystal. The elemental analysis has been performed to ascertain the purity and stoichiometry of TTZS crystals. UV spectral analysis has been conducted in order to figure out the values of transmittance, band gap energy, Urbach's energy, nature of electronic transitions, reflectance, refractive index, optical and electrical conductivities, extinction coefficient and electrical susceptibility. Single oscillator parameters have also been calculated from the UV analysis. The dielectric response of the grown crystals has been thoroughly analyzed at different temperature values with varying frequencies. The ac conductivity studies are used to bring out the activation energy values of the electrical process. A theoretical approach has been adopted to unveil the solid state parameters of the crystal which include valence electron plasma energy, Penn gap, Fermi energy and polarisability. The second harmonic generation (SHG) efficiency of the title crystal has been evaluated by Kurtz-Perry technique. The correlation between the spectral and electrical properties with the non linear second harmonic generating efficiency of TTZS has been successfully substantiated.