Lead-free Ba(1-x)SrxTiO3 ceramics for room-temperature pyroelectric energy conversion

Abstract

Lead-free Ba(1-x)SrxTiO3 (BST) ceramics were fabricated to convert near-room-temperature waste heat to electric energy for creating self-powered and ‘battery-less’ systems. In comparison to thermoelectrics that are specifically used for harvesting heat with stable temperature span, pyroelectric converters based on Olsen cycle mechanism can harvest heat with temperature-vibration environment. Large energy conversion density (ND) was obtained in BST ceramics within the narrower temperature gradient (< 60 °C). In terms of the diffused phase transition (DPT) in BST ceramics, the extra slim hysteresis loops processed relatively low coercive field (Ec) and hysteresis loss, which can effectively enhance the ND owing to the wider electrical field interval. The effect of Curie temperature (Tc) tuned by the ratios of Ba/Sr on ND and applicable range of temperature were also systematically examined. At the same electrical field difference (07 MV/m), the optimal energy conversion properties were gained around the Tc, e.g., 0.36 J/cm3 for BST66/34 (Tc = 23 °C) within a temperature range between 25 °C and 65 °C, and 0.48 J/cm3 for BST72/28 (Tc = 43 °C) between 25 °C and 85 °C.