Hybrid microwave sintering and shifting of Tc in lead-free ferroelectric composition x(Ba0.7Ca0.3TiO3)-(1-x)(BaZr0.2Ti0.8O3)

Abstract

Lead free ceramic composition of x(Ba0.7Ca0.3)TiO3-(1-x)Ba(Zr0.2Ti0.8)O3 with variation in x as, 0.15, 0.3, 0.4 and 0.5 was synthesized by hydroxide coprecipitation method. Synthesized compositions are subjected to sintering by microwave method at 1200 °C. After being sintered composite samples are characterized by various techniques for their structural, microstructural analysis, temperature dependent dielectric measurements, ferroelectric property and Raman spectroscopic analysis. From x-ray diffraction pattern the coexistence of tetragonal and rhombohedral crystal structures is observed. Broadening of Raman peaks at room temperature and two dielectric anomaly i.e. at lower temperature (R-T) and at higher temperature (T-C) in the temperature dependent dielectric spectroscopy could be assigned to the mutual existence of rhombohedral and tetragonal phases. Microstructural images confirm the well-separated grains having an irregular shape with a higher density. The transition temperature (Tc) (ferroelectric-paraelectric) shifts from 95 °C to 140 °C as the increase of BCT in the composition. Broad nature in the dielectric relaxation spectroscopic study reveals the existence of diffuse phase transition nature for samples. The saturated ferroelectric loop was observed for MPB composition 0.5BCT-0.5BZT. With the comparable values of Tc, ferroelectric parameters, existence of triple point and diffuse phase transition this type of lead-free materials found a suitable candidate to replace the lead-based materials.