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Bulk nanocomposites ZnO–SnO2–TiO2were synthesized by solid-state reaction method. The X-ray diffraction patterns and Raman spectra of bulk nanocomposite as a function of sintering temperature (700 °C–1300 °C) indicate that the structural phases of SnO2and TiO2depend on the sintering temperature while the ZnO retains its hexagonal wurtzite phase at all sintering temperatures and SnO2started to transform into SnO at 900 °C and completely converted into SnO at 1100 °C, whereas the titanium dioxide (TiO2) exhibits its most stable phase such as rutile at low sintering temperature (≤900°C) and it transforms partially into brookite phase at high sintering temperature (≥ 900 °C). The optical band gap of nanocomposite ZnO–SnO2–TiO2sintered at 700 °C, 900 °C, 1100 °C and 1300 °C for 16 hours is calculated using the transformed diffuse reflectance ultra violet visible near infra red (UV–VisNIR) spectra and has been found to be 3.28, 3.29, 3.31 and 3.32 eV, respectively. [ABSTRACT FROM PUBLISHER]

Preliminary results on magnetic and transport properties of a thin film of disordered Fe2CrAl deposited on (111) Si by pulsed laser deposition is reported in this study. While the bulk arc melted ingot used as target for the deposition is purely ferromagnetic, the film shows the co-existence of different magnetic phases, which arises due to the granular nature of the film. This is because, although the average composition pertains to Fe2CrAl, local disorder results in the formation of grains with different magnetic states that may be ferromagnetic or may consist of magnetic clusters. The resulting magnetic inhomogeneity of the thin film leads to large values of negative temperature coefficient of resistance of ∼22%/K at 260 K. [ABSTRACT FROM AUTHOR]

In the present investigation, the effects of annealing in oxygen atmosphere on the electrical and optical properties of pulsed direct-current (DC) magnetron-sputtered ZnO thin films have been studied. With annealing, the electrical conductivity was found to increase from 2.3 S cm to 123 S cm. The optical transparency was also found to improve from 83% to 90%. The improvement in the electrical properties with annealing is attributed to the reduction of the grain boundary potential from 34 meV to 8 meV. X-ray photoelectron spectroscopy (XPS) measurements revealed oxygen deficiency in as-deposited films, whereas adequate incorporation of oxygen was observed in the annealed films. Ultraviolet photoelectron spectroscopy (UPS) measurements showed a shift of +0.8 eV in the Fermi level with annealing. This shift indicates significant changes in the electrical conductivity with annealing, which is due to an increase in the carrier concentration. [ABSTRACT FROM AUTHOR]

Different concentrations (i.e., 10, 20, 30, and 40 wt%) of Al metal are dispersed in polymethylmethacrylate (PMMA) matrix and the composite films are prepared by solution casting method. The frequency and temperature dependence of dielectric constant, dielectric loss, and conductivity of pure polymer and polymer composites filled with Al-metal filler are studied in the broad frequency range from 100 Hz to 10 MHz and in the temperature range 25—80°C. It is observed that the dielectric constant, dielectric loss, and electrical conductivity gradually increase with filler concentration and also with temperature and is explained in terms of hopping conduction mechanism. The electrical conductivity of the composites obeys universal power law model (i.e., σ = Af n), where n is power exponent. A comparison of dielectric constant values of PMMA/Al composites is made with predictions of theoretical models and it is observed that an empirical power equation gives a better fit to our results. Structural property of the composites is studied by means of X-ray diffraction. The results show that the crystallinity and crystalline size increase with increasing concentration of aluminum filler. Average surface roughness is observed to change with filler concentration as obtained from atomic force microscopy and scanning electron microscopy analysis. [ABSTRACT FROM AUTHOR]