Aurang Zeb

Structural and dielectric relaxor properties of Ba1-xMgxTiO3 ceramics prepared through a hydrothermal route

ABSTRACT Polycrystalline samples of lead-free Ba1-xMgxTiO3 (where x = 0.05, 0.10, 0.15) have been fabricated by a hydrothermal method. Single-phase perovskite-type X-ray diffraction patterns were observed and samples have a phase with a tetragonal structure at room temperature for all compositions. The SEM image of the powder shows the agglomeration with increment of Mg concentrations. Small grains with average grain sizes of ∼20 ± 5 nm are uniformly distributed over the mesocrystals. TEM specimens show well-dispersed spherical barium magnesium titanate nanoparticles and diameter of these particles is around 270–300 nm. A dielectric study of Ba1-xMgxTiO3 ceramics as a function of temperature suggested that with increasing substitution concentration the dielectric constant decreased and the Curie temperature shifted towards the lower temperature side. The dielectric diffusivity (γ) was found to be maximum (1.86) for substitution of x = 0.10 in Ba1-xMgxTiO3 compounds. The activation energy (Ea) was found to increases with increasing substitution concentration in BMT compounds.

Modification of structural and electrical properties of Ca element on barium titanate nano-material synthesized by hydrothermal method

ABSTRACT Ba1-xCaxTiO3 (x = 0.10, 0.15, 0.20 and 0.25) ceramics were prepared by using standard Sol-Gel hydrothermal reaction technique at 150°C. Structural and dielectric properties were carry out by using X-ray diffraction and dielectric constant, tangent loss and conductivity measurements. Single-phase perovskite-type X-ray diffraction patterns were observed and the samples have a phase with a tetrahedral structure at room temperature for all the compositions. SEM image of Ba1-xCa xTiO3 powder shows inhomogeneity with the increment of Ca element. Small grains with average grain sizes of ∼20 ± 5 nm uniformly distributed over the mesocrystals. The temperature dependence of the dielectric permittivity of tetrahedral Ba1-xCaxTiO3 ceramic as a function of frequency (1 kHz-100 kHz) at different temperature (RT–300°C) provided useful information on electrical behavior (Ferroelectric-Relaxor relationship). The behavior of the dielectric graph (in paraelectric region) confirmed the relaxor behavior of the material at high temperature (160–300°C) range. Nature of diffusivity graph also indicating that, increase of Ca content improved the diffusivity of materials. Values of Tm increased with increasing x = 0.10– 0.25, from ∼120°C to 140°C. In the comparison of other, the composition Ba0.90Ca0.10TiO3 reveals strong results. It has dielectric permittivity (ϵ) 5741 ± 200 at the low value of loss tanδ = 0.009 ± .091 along with the transition temperature (Tc) at ∼131 ± 2 shows diffusivity 1.72 ± 10 < 2 and activation energy 0.821 ± .030.