Iranian Journal of Materials Science and Engineering

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The study of amino acid based nonlinear optical (NLO) materials with optimum physical properties is an important area due to their practical applications such as optical communication, optical computing, optical information processing, optical disk data storage, laser fusion reactions, laser remote sensing, colour display, medical diagnostics, etc. Also, microelectronic industries require crystals which possess low dielectric constant at higher frequency. Keeping this in view, attempts have been made to grow nonlinear optical crystals and study their optical, electrical and mechanical properties. Nonlinear optical single crystals of dichloro-diglycine zinc II have been grown by slow evaporation method. The grown crystals were characterized using single crystal X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), UV-VIS-NIR spectrum, thermal, mechanical and dielectric studies. The results of characterization studies have been discussed in detail to understand their properties. The grown crystals have better thermal stability and sufficient mechanical strength. They are capable of inducing polarization due to dielectric behaviour when powerful laser beam is incident on them. The various characterization studies suggest that the grown crystals are promising materials for optoelectronic and nonlinear optical applications.

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The work reported in this paper was focused on the investigation of surface morphological, microstructural, and optical features of polycrystalline BaTiO₃ thin film deposited on p-type Si < 100 > substrate using e-beam PVD (physical vapor deposition) technique. The influence of annealing over the surface morphology of the thin film was analyzed by X-ray diffraction, atomic force microscopy and scanning electron microscopy characterization methods. When the annealing temperature was increased from as-deposited to 800 °C there was a significant growth in the grain size from 28.407 nm to 37.89 nm. This granular growth of BaTiO₃ made the thin film appropriate for nanoelectronic device applications. The roughness of the annealed film got increased from 31.5 nm to 52.8 nm with the annealing temperature. The optical bandgap was computed using Kubelka-Munk (KM) method which got reduced from 3.93 eV to 3.87 eV for the as-deposited to the 800 °C annealed film. The above reported properties made the annealed film suitable for optoelectronic applications. For polycrystalline BaTiO₃ thin film the refractive index varied from 2.2 to 1.98 from 400 to 500 nm and it was 2.05 at 550 nm wavelength. The broad peaks in Raman spectra indicated the polycrystalline nature of the thin film. It had been also observed that with the annealing temperature the intensity of the Raman bands got increased. From these results, it was proved that annealing significantly improved the crystallinity, microstructural, surface morphological and optical features of the barium titanate thin film which made it suitable as sensors in biomedical applications as it is cost-effective, lead-free and environment friendly material.