Electro-thermal synergetic effect in 0.94Bi0.5Na0.5TiO3-0.06BaZr0.2Ti0.8O3: ZnO pyroelectric composites for high-performance thermal energy harvesting

Abstract

Pyroelectric energy harvesters based on lead-free ceramics cannot meet the requirement for practical applications due to their low energy conversion capacity. In this work, high-performance thermal energy harvesting with the greatly enhanced pyroelectric coefficient and rate of temperature change has been achieved by compositing the zinc oxide (ZnO) semiconductor into 0.94Bi0.5Na0.5TiO3-0.06BaZr0.2Ti0.8O3 (BNT-BZT) ceramic matrixes. The ZnO semiconductor not only provides charge carriers for accelerating the transportation of free charge to improve the pyroelectric coefficient of BNT-BZT: ZnO but also enhances the temperature variation rate dT/dt of the samples because of its high thermal conductivity. Owing to the electrothermal synergetic effect of the ZnO semiconductor, a highly improved energy harvesting performance of the energy density reaching up to 130 μJ cm−3 is achieved, which is over three times compared to that of the pristine BNT-BZT ceramics. This work will provide an effective and facile approach to develop high-performance pyroelectric composite ceramics for thermal energy harvesting applications.