• T P Sinha

Articles written in Bulletin of Materials Science

• Preparation, characterization and dielectric behaviour of some yttrium doped strontium stannates

Samples of Sr$_{(1–3x/2)}$Y$_x$SnO3 are prepared by usual solid state reaction route. X-ray diffraction studies confirm the formation of single cubic perovskite single phase. The dielectric constant and dielectric loss at 1 kHz were measured in the temperature range from room temperature up to ≅ 150°C. The dielectric constant decreases and losses increase with increased yttrium content in the samples. The percentage porosity and unit cell parameters are also calculated for the samples.

• Relaxor behaviour of (Ba0.5Sr0.5)(Ti0.6Zr0.4)O3 ceramics

Ba0.5Sr0.5Ti0.6Zr0.4O3 ceramic has been prepared through solid state reaction route. X-ray diffraction shows that the sample has cubic perovskite structure with space group 𝑃𝑚–3𝑚 at room temperature. Temperature dependent dielectric study of the ceramic has been investigated in the frequency range 50 Hz–1 MHz. The density of the sample is determined using Archimedes’ principle and is found to be ∼99% of X-ray density. The dielectric study revealed diffuse phase transition of second order. A broad dielectric anomaly coupled with the shift of dielectric maxima toward a higher temperature with increasing frequency indicates the relaxor-type behaviour in the ceramics. The index of relaxation (𝛾) and the broadening parameter (𝛥) were estimated from a linear fit of the modified Curie–Weiss law. The value of 𝛾 ∼ 1.72 indicates the strong relaxor nature of the ceramic. A remarkably good fit to the Vogel–Fulcher relation further supports such a relaxor nature.

• Dielectric relaxation in double perovskite oxide, Ho2CdTiO6

A new double perovskite oxide holmium cadmium titanate, Ho2CdTiO6 (HCT), prepared by solid state reaction technique is investigated by impedance spectroscopy in a temperature range 50–400°C and a frequency range 75 Hz–1 MHz. The crystal structure has been determined by powder X-ray diffraction which shows monoclinic phase at room temperature. An analysis of complex permittivity with frequency was carried out assuming a distribution of relaxation times as confirmed by Cole–Cole plot. The frequency dependent electrical data are analysed in the framework of conductivity and electric modulus formalisms. The frequencies corresponding to themaxima of the imaginary electric modulus at various temperatures are found to obey an Arrhenius law with an activation energy of 0.13 eV. The scaling behaviour of imaginary part of electric modulus suggests that the relaxation describes the same mechanism at various temperatures. Nyquist plots are drawn to identify an equivalent circuit and to know the bulk and interface contributions.

• # Bulletin of Materials Science

Current Issue
Volume 42 | Issue 6
December 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019