• T Badapanda

      Articles written in Bulletin of Materials Science

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

      T Badapanda S K Rout S Panigrahi T P Sinha

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      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.

    • Diffuse phase transition, piezoelectric and optical study of Bi0.5Na0.5TiO3 ceramic

      B Parija T Badapanda V Senthil S K Rout S Panigrahi

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      Bismuth sodium titanate, Bi0.5Na0.5TiO3 (BNT) is considered to be an excellent candidate for a key material of lead-free dielectric ceramics. In this study, we propose the dielectric and optical study of single phase BNT powder prepared by solid-state reaction route. The phase formation and structural study were done by X-ray diffraction (XRD) which shows well developed crystallite with a pure perovskite phase. The ceramic was sintered at different temperatures from 1050°C to 1175°C to study the effect of sintering temperature on the morphology and density. It was found that the sample sintered at 1150°C shows the highest density. The microstructure of the ceramic was investigated by scanning electron microscopic (SEM) technique. The temperature-dependent dielectric study of the sample sintered at 1150°C was done in the frequency range of 50 kHz–1 MHz which shows a diffuse phase transition. The piezoelectric constant (𝑑33) was found to be 41 pCN-1. The P–E hysteresis loop confirms the ferroelectric behaviour in the ceramic. The UV–Vis spectrum indicated that the Bi0.5Na0.5TiO3 ceramic has an optical band gap of 2.94 eV.

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