Investigation of structural, morphological, dielectric, optical, and ferroelectric-energy storage properties of [(1-x) BCT-(x) BZT] electroceramics

Abstract

Extensive research and advancements have been progressed by the vast potential of eco-friendly dielectric capacitors in high-level electronic elements and high-performance pulsed power systems thus far. Ferroelectric ceramic materials exhibiting relaxor properties and significant dielectric constants are prime candidates for attaining exceptional energy storage capabilities. Herein, a lead-free (1-x) Ba0.9Ca0.1TiO3–xBaZr0.15Ti0.85O3 (abbreviated as (1-x) BCT-xBZT) solid solution system has been synthesized via the conventional solid-state reaction technique, with varying levels of BZT doping. The X-ray diffraction study confirmed pure perovskite structure formation in the prepared ceramics, and the coexistence of orthorhombic (O) (space group- Amm2) and tetragonal (T) (space group-P4mm) phases has been detected through the Rietveld refinement technique at room temperature. Rietveld refinement data and associated analysis highlight the gradual shift of crystal symmetry from Amm2 to P4mm as the x content increases. Replacing BZT in Ca-modified BaTiO3 has led to significant enhancements in microstructural properties and an increase in the width of the optical band gap. This, in turn, enhances energy storage capabilities compared to pure BCT. Incorporating BZT into BCT has led to the evolution of relaxor ceramics, a crucial development for achieving elevated levels of recoverable energy storage density. In this study, the solid solution comprising 0.6BCT-0.4BZT exhibits distinct traits, including a diffuse phase transition, high breakdown strength, shallow dielectric loss (tanδ <0.007), and significantly high dielectric constant. Due to enhanced electrical characteristics, the 0.6BCT-0.4BZT possesses very high saturation polarization of ∼48 μCcm−2, a total energy density of 1.71 J/cm3, and a recoverable energy density of 1.1 J/cm3. In addition, the optimized ceramics demonstrate concurrent achievement of high-frequency stability (10–250 Hz), fatigue resistance (up to 104 cycles), and favorable temperature stability (20–160°C). This study showcased a potential material candidate suitable for energy storage devices functioning within low to medium-electric fields.