Boosting energy harvesting performance in (Ba,Ca)(Ti,Zr)O 3 lead-free perovskites through artificial control of intermediate grain size.

In this study, (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) lead-free ceramics with enhanced energy density were prepared by two-step sintering. All ceramics fall into the rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary near room temperature, and a dense microstructure with an intermediate grain size was observed. The enhanced piezoelectric and energy harvesting properties were attained over a wide grain size range of 10-15 μm, benefiting from the construction of the R-O-T phase boundary. Most interestingly, the maximum values of d33 and d33 × g33 (530 pC N-1 and 9720 × 10-15 m2 N-1) can be achieved at 1500/1350 °C with a grain size of 13.7 μm. The interpretation of the underlying mechanism related to domain and defect engineering has been investigated systematically. Furthermore, a high output power of 99 μW and an energy conversion efficiency of 10% were obtained at a simple cantilever energy harvester fabricated from a 1500/1350 °C specimen under an acceleration of 1.0g, making the current system very promising for piezoelectric energy harvesting applications.