Structure evolution, ferroelectric properties, and energy storage performance of CaSnO₃ modified BaTiO₃-based Pb-free ceramics

Pb-free bulk (1-x)BaTiO₃-xCaSnO₃, (x = 0.05, 0.10, 0.15, 0.20 mol) ceramics were fabricated with traditional electroceramic processing technology, and the influences of CaSnO₃ on the microstructure, morphology, and electrical performance were systemically investigated. All doped ceramics exhibit a single perovskite structure according to the X-ray diffraction (XRD) and Raman spectra. Moreover, the modification mechanism of co-doping with Ca and Sn was investigated. CaSnO₃ effects the grain refinement significantly, shifts the phase transition peak to lower temperatures, and enhances the relaxor behaviour. According to the impedance spectra, its effect on the insulation performance transforms from grain boundary contribution to grain contribution as the substitution content increases. When the substitution content is 0.15 mol, the maximum dielectric breakdown strength (BDS) and the maximum energy storage density reach 230 kV/cm, and 1.57 J/cm³, respectively. Furthermore, the BT-0.15CS ceramic shows very good temperature, frequency, fatigue resistance, and charge-discharge performances, which makes it suitable for energy storage applications.