Mohd. Shakir

Enhancement of second harmonic generation, optical and dielectric properties in l-asparagine monohydrate single crystals due to an improvement in crystalline perfection by annealing

Single crystals of the relatively new nonlinear optical material l-asparagine monohydrate have been successfully grown by the slow evaporation solution growth technique at room temperature in aqueous solution. The crystal system of the title material has been confirmed by powder X-ray diffraction. The crystalline perfection of the as-grown and annealed crystals has been evaluated by high-resolution X-ray diffraction. The as-grown single crystals (particularly when their size is large) were found to contain internal structural grain boundaries, and the crystalline perfection of these crystals was found to be improved substantially by annealing at low temperatures. The crystalline perfection and the measured physical properties were found to be correlated such that the second harmonic generation efficiency, optical transparency, fluorescence and dielectric properties are enhanced as the crystal quality improves.

Synthesis, growth, crystal structure and characterization of a new organic material: Glycine glutaric acid

Glycine glutaric acid, a new organic compound has been synthesized and good quality single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal XRD. The presence of the functional groups was confirmed by using FT-IR spectroscopy. The optical transparency was studied by using UV-vis spectrophotometer and it was found that the crystal is having high optical transparency. The thermal stability of the crystal was studied by using thermo-gravimetric and differential thermal analyses and found that it is stable up to 150°C. The room temperature dielectric studies were also carried out over the wide frequency range: 10 mHz to 10 MHz.

Effect of crucible design on crystalline perfection and the enhanced optical properties of benzimidazole single crystals grown by the vertical Bridgman technique

Good quality benzimidazole (BMZ) single crystals were successfully grown by the vertical Bridgman technique (VBT). The unavoidable thermal-induced structural grain boundaries formed in the normal VBT growth of these crystals with low melting point were controlled by using a double-wall ampoule. The grown single crystals were subjected to high-resolution X-ray diffraction to assess their crystallinity. The enhancement of optical properties due to the improvement in crystalline perfection is also reported.