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Sol gel spin coating method has been successfully employed for the deposition of nanocrystalline nickel oxide (NiO) thin films. The films were annealed at 400°C - 700°C for 1 h in an air and changes in the structural, morphological, electrical and optical properties were studied. The structural properties of nickel oxide films were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that all the films are crystallized in the cubic phase and present a random orientation. Surface morphology of the nickel oxide film consists of nanocrystalline grains with uniform coverage of the substrate surface with randomly oriented morphology. The electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 10^-4 to 10^-2(Ωcm)^-1 after annealing. The decrease in the band gap energy from 3.86 to 3.47 eV was observed after annealing NiO films from 400^oC - 700^oC. These mean that the optical quality of NiO films is improved by annealing

Nanocrystalline copper oxide (CuO) thin films have been synthesized by a sol-gel method using cupric acetate Cu (CH 3 COO) as a precursor. The as prepared powder was sintered at various temperatures in the range of (300-700°C) and has been deposited onto a glass substrates using spin coating technique. The structural, compositional, morphological, electrical optical and gas sensing properties of CuO thin films have been studied by X-ray diffraction, Scanning Electron Microscopy (SEM), Four Probe Resistivity measurement and UV-visible spectrophotometer. The variation in annealing temperature affected the film morphology and optoelectronic properties. X-ray diffraction patterns of CuO films show that all the films are nanocrystallized in the monoclinic structure and present a random orientation. The crystallite size increases with increasing annealing temperature (40-45 nm). The room temperature dc electrical conductivity was increased from 10 -6 to 10 -5 (X cm) -1 , after annealing due to the removal of H 2 O vapor which may resist conduction between CuO grain. The thermopower measurement shows that CuO films were found of n-type, apparently suggesting the existence of oxygen vacancies in the structure. The electron carrier concentration (n) and mobility (l) of CuO films annealed at 400-700°C were estimated to be of the order of 4.6-7.2 9 10 19 cm -3 and 3.7-5.4 9 10 -5 cm 2 V -1 s -1 respectively. It is observed that CuO thin film annealing at 700°C after deposition provide a smooth and flat texture suited for optoelectronic applications. The optical band gap energy decreases (1.64-1.46 eV) with increasing annealing temperature. It was observed that the crystallite size increases with increasing annealing temperature. These modifications influence the morphology, electrical and optical properties.

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Polycrystalline Pb(Mn 0⋅ ⋅5 W 0⋅ ⋅5)O 3 , a ferroelectric oxide having perovskite structure, was prepared by high temperature solid state reaction technique. Preliminary X-ray diffraction analysis confirms single phase formation with the lattice parameters a = 7⋅ ⋅2501 Å, b = 8⋅ ⋅1276 Å and c = 12⋅ ⋅0232 Å. Room temperature dielectric constant (ε ε′ ′) and loss tangent (tan δ δ) were scanned with respect to frequency in the range 100 Hz-1 MHz. Detailed study of dielectric constant and electrical conductivity reveals a phase change around 400 K, which is quite different from those in the other materials of the same type. Further, the seebeck coefficient (α α) is temperature independent. The conduction is interpreted as due to small polaron hopping.