Thermal energy conversion and temperature-dependent dynamic hysteresis analysis for Ba 0.85 Ca 0.15 Ti 0.9-x Fe x Zr 0.1 O 3 ceramics

Abstract

Temperature-dependent ferroelectric behavior in Ba 0.85 Ca 0.15 Ti 0.9-x Fe x Zr 0.1 O 3 (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/m 3 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 (E c ) and remnant polarization (P r ) 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 E c ∝ T -0.658 , E c ∝ T -0.687 and E c ∝ T -0.717 for 0%, 0.5% and 1% Fe, respectively. Similarly, P r ∝ T -1.59 , P r ∝ T -1.65 and P r ∝ T -1.85 are for 0%, 0.5% and 1% Fe, respectively. Additionally, back-switching polarization (P bc ) behavior as a function of temperature is estimated by well-described Arrhenius law to evaluate the average activation energy for all the compositions.