Ultrahigh energy harvesting properties in textured lead-free piezoelectric composites

Piezoelectric energy harvesters have gained significant attention in recent years due to the strong demand of sustainable power sources for wireless sensor networks and portable/wearable electronics. However, the relatively low figure of merit (d x g) induced by thermodynamic constraints seriously hinders the enhancement of power generation capability in lead-free piezoelectrics. In this work, crystallographic texture and composite design strategies were integrated to develop novel 0-3 type (Ba, Ca)(Ti, Sn)O-3/BaTiO3 (BCTS/BT) composites with highly [001](c)-oriented and "core-shell" structured grains to resolve this challenge. Increasing texture degree F-001 above 86% enabled rapid enhancements of piezoelectric charge/strain coefficients d(33) and d(33)*. Meanwhile, the inclusion of low-epsilon(r) BT microcrystals inside the oriented BCTS grains effectively suppressed the dielectric permittivity epsilon(r) of the composites, thus remarkably improving the piezoelectric voltage coefficient g(33). Especially, the 98%-textured 0-3 composites demonstrated as high as similar to 405% improvement in d(33) x g(33) value (17.0 x 10(-12) m(2) N-1), attributed to the strong piezoelectric anisotropy, the formation of much finer domains and the elastoelectric composite effect. The cantilever energy harvesters based on such composites possessed similar to 560% enhancement in power density (4.5 mu W mm(-3)) at 1 g acceleration relative to the non-textured counterpart, which significantly outperformed many previously reported lead-free piezoelectrics. This work provides a new important paradigm for developing high-performance viable green energy harvesters, which can largely expand the application fields of lead-free piezoelectrics.