Thermal energy conversion and temperature-dependent dynamic hysteresis analysis for Ba0.85Ca0.15Ti0.9−xFexZr0.1O3 ceramics

Abstract

Temperature-dependent ferroelectric behavior in Ba0.85Ca0.15Ti0.9−xFexZr0.1O3 (BCT-BZT-Fe) (x = 0%, 0.5%, 1%) has been investigated. Olsen cycle is used to estimate the thermal energy conversion potential in the compositions under study. The maximum energy conversion density of 305 kJ/m3 per cycle is obtained for BCT-BZT-Fe (0.5% Fe content) when the cycle is operated between 30 and 110 °C and an electric field of 0–3 MV/m. The obtained energy density is very high for small electric field and temperature gradient as compared to other lead-free ferroelectric materials. A comparison table of previously reported Olsen cycle-based energy conversion in bulk ferroelectric ceramics is presented. Temperature also affects the hysteresis parameters, therefore, scaling relations for coercive field (Ec) and remnant polarization (Pr) as a function of temperature (T) were also observed. The power-law exponents are obtained for all hysteresis parameters in the compositions under study. The scaling relations are found as Ec ∝ T−0.658, Ec ∝ T−0.687 and Ec ∝ T−0.717 for 0%, 0.5% and 1% Fe, respectively. Similarly, Pr ∝ T−1.59, Pr ∝ T−1.65 and Pr ∝ T−1.85 are for 0%, 0.5% and 1% Fe, respectively. Additionally, back-switching polarization (Pbc) behavior as a function of temperature is estimated by well-described Arrhenius law to evaluate the average activation energy for all the compositions.

Keywords

• Energy conversion
• Olsen cycle
• Dynamic hysteresis scaling
• Ferroelectric