No abstract

PbS and Cd-doped PbS nanocrystalline thin films prepared by the chemical bath deposition technique was deposited onto glass substrates at 80 • C. The aqueous solution containing Cd 2+ and Pb 2+ precursors was used to obtain good quality film deposits at optimized preparative parameters. The characterization of these films was performed using X-ray diffraction, optical absorption, photoluminescence properties, scanning electron microscopy and energy dispersive X-ray analyses to explore the properties of the PbS and Cd-doped PbS films. The prepared films were adherent to the substrate and well crystallized according to the cubic structure, which displayed a preferred orientation. According to the X-ray diffraction analysis, the crystallite size of the films decreased from 74 nm to 64 nm with increasing Cd doping. The optical properties were determined from ultraviolet-visible spectroscopy measurements in the absorbance energy range from 300-1200 nm. The UV-visible analysis shows that the band gap value of the PbS thin films increased from 2.12 eV to 2.65 eV by doping with Cd. Morphological analysis showed that the shape of the grains over the substrate surface was changed from a regular random orientation to an irregular shape with Cd doping. The energy dispersive X-ray analysis showed that the film contains Cd, Pb and S elements without any other impurities.

In the present study, L-alanine crystal is grown with cobalt chloride as dopant by low temperature solution growth using slow evaporation technique at room temperature. The lattice parameters of the grown pure and cobalt chloride doped L-alanine crystals were determined by the single crystal X-ray diffraction technique. The presence of the elemental composition such as cobalt chloride present in the L-alanine lattice was confirmed by energy dispersive X-ray analysis. The optical transmittance, absorbance, reflectance was measured and used to study the optical properties of the pure and doped L-alanine crystal. The pure L-alanine crystal has high optical transmittance in the whole visible range and UV transparency with lower cutoff wavelength at 240[Formula: see text]nm. By adding cobalt chloride to L-alanine crystal, the transmittance decreases the value of cutoff shifts to the higher wavelengths. Nonlinear optical studies reveal that the SHG efficiency and laser damage threshold energy increases when the L-alanine crystal is doped with cobalt chloride. From microhardness studies, it is observed that the cobalt chloride doped L-alanine crystal is harder than the pure crystal.

No abstract

CdZnS thinfims have been prepared on mineral glass substrate by spray pyrolysis method at different deposition temperature using the optimized coating parameters. The XRD profile of the films confirms hexagonal wurtizite structure with preferred orientation along the (101) pane. The different crystallographic parameters viz., lattice constant, c/a ratio, mean grain size, number of reflections per unit area, lattice strain, dislocation density, texture coefficient and standard deviation have been calculated from the experimentally observed XRD data and the effect of deposition temperature on these parameters have been elaborately discussed. The maximum optical transmittance of 84.5% (at λ= 650 nm ) has been observed for the CdZnS thin film spray deposited at the temperature 450 °C. The direct band gap energy calculated from the transmittance measurements lies between 2.82 eV and 3.4 eV. The electrical resistivity has been found to be low with the value 50 x 103 Ω - cm for the film deposited at the temperature 450 °C. The SEM micrographs of the films show uniform surface pattern associated with large accumulation of fine grains. The grain size estimated from the SEM analysis lies between 100 nm and 350 nm.