Papers by Author: A.S. Bhalla

Abstract: In this work, we used Monte Carlo simulation to investigate the uniaxial stress dependence of the relaxor dielectric properties. The Metropolis algorithm and the spin glass type interaction were used in updating the local polarizations (representing the polar nano-regions). The exchange interaction in the spin glass Hamiltonian was assumed to be stress dependent via the strain. From the results, the frequency dependence of the dielectric permittivity were found, where, at high enough stress, the dielectric permittivity decreases with increasing stresses in qualitatively good agreement with experiments. In addition, from the modified Curie-Weiss law, all ’s stay close to 2. Therefore, this implies the frequency dispersion universality of the relaxor system under loading conditions.

Abstract: Poly (vinylidene fluoride), Piezoelectric, Dielectric constant, Microporous PVDF films, Bubble shapes.

Abstract: We report the fabrication of the orientation preferred structures in BaTiO3 thin films on Ni substrates using pulsed laser deposition. Transmission electron microscopy studies showed that the films consist of crystalline structures of tetragonal BaTiO3. More than 60% of BaTiO3 grains in the films exhibit nearly the same crystallographic orientation with their a-axis lying in the film plane and the [011] direction parallel to the growth direction. Such orientation preferred structures were grown on a Ni nanocrystalline buffer layer. This result demonstrated the possibility of approximating an oriented single crystalline ceramic oxide structures on metallic substrates.