Tuesday, May 15, 2018

Synthesis and optical characterization of Nickel doped Thiourea Barium Chloride (TBC) single crystals

Organometallic Thiourea barium chloride (TBC) single crystals were synthesized using solution evaporation process at room temperature. Synthesized thiourea barium chloride crystals were recrystallized and during the recrystallization process 1M%, 2M% and 5M% of nickel (Ni) was added to the solution and kept for crystallization. The variation of intensity peaks and the shift in the XRD peaks were observed due to the incorporation of nickel in the host matrix. Variations in the absorbance and transmittance spectra of the pure and Ni doped crystals further confirms the presence of nickel in TBC single crystal. The optical bandgap of the pure and nickel doped single crystals were calculated using Touc's relation. The results show that bandgap decreased with the dopant concentration in the thiourea barium chloride crystal. The optical constants such as extinction coefficient and reflectance were also studied using the absorption spectrum. The FTIR absorption also shows minute shift in the absorption peaks due to the presence of nickel in the host matrix. Photoluminescence spectra of pure and doped crystals were studied.


Source:IOPscience

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Tuesday, May 8, 2018

Optical, mechanical and thermal characterization of l-threonine single crystals grown in dimethyl urea solution

An organic material of a noncentrosymmetric l-threonine single crystal was grown in a dimethyl urea solution using the slow evaporation method. The grown crystal was transparent and colorless, with a size of about 20 × 7 × 4 mm3, obtained within a period of 10 days. The grown crystal was subjected to various studies, such as x-ray diffraction (XRD), Fourier transform infrared (FTIR), microhardness, ultraviolet–visible (UV–Vis) transmittance, thermogravimetric analysis and differential thermal analysis (TGA/DTA) and second harmonic generation (SHG). l-threonine crystals grown in a dimethyl urea solution show relative SHG efficiency of 0.92 times that of potassium dihydrogen phosphate. The functional groups of the crystals have been confirmed by FTIR analysis. The mechanical strength of the crystal was estimated by the Vickers hardness test. The lattice parameters of the grown crystal were determined by single crystal XRD and powder XRD studies, and the diffraction peaks were indexed. A UV–Vis spectrum was recorded in the wavelength range of 200–1100 nm to find the suitability of the crystal for nonlinear optical applications. The thermal stability of l-threonine crystal grown in dimethyl urea was checked using the TGA/DTA analysis.


Source:IOPscience

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