Enhancement of SHG efficiency by urea doping in ZTS single crystals and its correlation with crystalline perfection revealed by Kurtz powder and high-resolution X-ray diffraction methods

摘要

Enhancement of second harmonic generation (SHG) efficiency and thecorrelation between crystalline perfection and SHG with urea doping ontristhioureazinc(II) sulphate (ZTS) single crystals have been investigated. ZTSis a potential semiorganic nonlinear optical (NLO) material. Pure and ureadoped single crystals of ZTS have been successfully grown by slow evaporationsolution technique (SEST). Presence of dopants has been confirmed and analyzedby Fourier transform infrared (FTIR) spectrometer. The influence of urea dopingat different concentrations on the crystalline perfection has been thoroughlyassessed by high resolution X-ray diffractometry (HRXRD). HRXRD studiesrevealed that the crystals could accomodate urea in ZTS up to some criticalconcentration without any deterioration in the crystalline perfection. Abovethis concentration, very low angle structural grain boundaries were developedand it seems, the excess urea above the critical concentration was segregatedalong the grain boundaries. At very high doping concentrations, the crystalswere found to contain mosaic blocks. The SHG effeiciency has been studied byusing Kurtz powder technique. The relative SHG efficiency of the crystals wasfound to be increased substantially with the increase of urea concentration.The correlation found between the crystalline perfection and SHG efficiency wasdiscussed.