Thermoelectric coupling effect in BNT-BZT-xGaN pyroelectric ceramics for low-grade temperature-driven energy harvesting
Meng Shen, Kun Liu, Guanghui Zhang, Qifan Li, Guangzu Zhang, Qingfeng Zhang, Haibo Zhang, Shenglin Jiang, Yong Chen, Kui Yao
Abstract
Abstract Pyroelectric energy harvesting has received increasing attention due to its ability to convert low-grade waste heat into electricity. However, the low output energy density driven by low-grade temperature limits its practical applications. Here, we show a high-performance hybrid BNT-BZT- x GaN thermal energy harvesting system with environmentally friendly lead-free BNT-BZT pyroelectric matrix and high thermal conductivity GaN as dopant. The theoretical analysis of BNT-BZT and BNT-BZT- x GaN with x = 0.1 wt% suggests that the introduction of GaN facilitates the resonance vibration between Ga and Ti, O atoms, which not only contributes to the enhancement of the lattice heat conduction, but also improves the vibration of TiO 6 octahedra, resulting in simultaneous improvement of thermal conductivity and pyroelectric coefficient. Therefore, a thermoelectric coupling enhanced energy harvesting density of 80 μJ cm −3 has been achieved in BNT-BZT- x GaN ceramics with x = 0.1 wt% driven by a temperature variation of 2 o C, at the optical load resistance of 600 MΩ.