Iranian Journal of Materials Science and Engineering

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Abstract: Lead-containing glass borosilicate was synthesized by Sol-gel technique using metalalkoxids such as tetraethyleorthosilicate (TEOS), Al-sec-butoxide and trimethyl borate. The sol containing TEOS converts to gel during drop wise addition of Al-alkoxide while inorganic lead salt was added in the last stage of gelation to prepare the alcogels. The specimens were dried at room temperature to set then heated at 600°C quickly to avoid crystallization preparing a glass containing 63 wt% lead oxide. The influence of pH on absorption behavior of the sols studied by UV visible technique so the characteristic of the gel, alcogel and xerogel were studied in the different acidic concentrations. The UV spectrums show that the higher the acidity of the hydrolysis stages, the higher the absorbance. The results showed the sample with 63 wt% lead was found fully amorphous. Microstructure and phase analysis of the glass powders were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM) equipped with EDS analysis.

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Ultraviolet–Visible (UV–Vis) spectroscopy was used, in the current investigation, to explore the dispersion and stability of titania nanoparticles in an aqueous media with different types of dispersants. Hydrochloric and nitric acids as well as ammonia were used to determine the stability of the suspension in the acidic region (pH=2.5) and basic area (pH=9.5), respectively. In addition, for measuring sustainability of suspension and creating steric, and electrosteric repulsive forces, ethylene glycol and ethylene glycol plus ammonia were employed, respectively. UV–V is
spectrometry was applied to realize the effect of nano titania concentrations and different types of dispersants of samples containing different amounts of nano titania and different types of dispersants on stability of TiO2-containing suspensions. In addition, the stability of dispersion could be evaluated in colloidal mixtures containing ethylene glycol plus ammonia. It was demonstrated that the mixtures containing ethylene glycol plus ammonia were stable over a period of 4 days. To support the UV–Vis results, other techniques such as atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to study the degree of agglomeration of titania nanoparticles in terms ofmorphology and size.

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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.

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