Ferroelectric glass-ceramics, with a basic composition (1Ày)(Ba 0.70 Sr 0.30 )TiO 3 -y(B 2 O 3 -x SiO 2 ), were synthesized by sol-gel method. The major crystalline phase is the perovskite, which exhibited volume nucleation. The formation of the crystalline phase, particle size, morphology, kinetics, and mechanism of crystallization of the ferroelectric in the glass matrix have been studied using differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The kinetic parameters characterizing the crystallization of the perovskite phase have been determined using an Arrhenius model. The effect of glass content on the dielectric properties and the influence of the glass composition on the crystallization have also been investigated and are reported.

The annealing effect on the spectral and nonlinear optical (NLO) characteristics of ZnO thin films deposited on quartz substrates by sol-gel process is investigated. As the annealing temperature increases from 300–1050 °C, there is a decrease in the band gap, which indicates the changes of the interface of ZnO. ZnO is reported to show two emission bands, an ultraviolet (UV) emission band and another in the green region. The intensity of the UV peak remains the same while the intensity of the visible peak increases with increase in annealing temperature. The role of oxygen in ZnO thin films during the annealing process is important to the change in optical properties. The mechanism of the luminescence suggests that UV luminescence of ZnO thin films is related to the transition from conduction band edge to valence band, and green luminescence is caused by the transition from deep donor level to valence band due to oxygen vacancies. The NLO response of these samples is studied using nanosecond laser pulses at off-resonance wavelengths. The nonlinear absorption coefficient increases from 2.9×10−6 to 1.0×10−4 m/W when the annealing temperature is increased from 300 to 1050 °C, mainly due to the enhancement of interfacial state and exciton oscillator strength. The third order optical susceptibility χ(3) increases with increase in annealing temperature (T) within the range of our investigations. In the weak confinement regime, T2.4 dependence of χ(3) is obtained for ZnO thin films. The role of annealing temperature on the optical limiting response is also studied.

Nanocrystalline Zn1−xMgxO thin films with an average particle diameter of 60nm have been deposited on glass substrates using a sol-gel spin-coating technique. Within the range of compositions, 0⩽x⩽0.20, the optical band gap could be tuned between 3.40 and 3.83eV. The nonlinear optical transmission in the visible spectral region is investigated using ultrafast (100fs) and short (7ns) laser pulses at off-resonant wavelengths. The observed nonlinearity is strong and is comparable to that recently obtained in ZnO nanocomposite layers ion-implanted with Cu+ ions.

Hydrolytic reactions of metal alkoxides offer a broad range of possibilities for their use in the preparation of ceramic powders. This paper reports a unique and novel process to prepare fine powders of BaTiO 3 and SrTiO 3 from stable precursor solutions by carefully controlling the pH and temperature. This simple route offers good control of stoichiometry and the powders are agglomerate-free with fine particles of size 0.06-0.1 µm and were well sintered at 1200°a nd 1350°C, respectively. The dielectric properties of the dense ceramics are also reported. The formation aspects of these perovskite phases are also discussed.