Ultrahigh energy harvesting properties in textured lead-free piezoelectric composites

Abstract

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 × 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)O₃/BaTiO₃ (BCTS/BT) composites with highly [001]_c-oriented and “core–shell” structured grains to resolve this challenge. Increasing texture degree F₀₀₁ above 86% enabled rapid enhancements of piezoelectric charge/strain coefficients d₃₃ and . Meanwhile, the inclusion of low-ε_r BT microcrystals inside the oriented BCTS grains effectively suppressed the dielectric permittivity ε_r of the composites, thus remarkably improving the piezoelectric voltage coefficient g₃₃. Especially, the 98%-textured 0–3 composites demonstrated as high as ∼405% improvement in d₃₃ × g₃₃ value (17.0 × 10⁻¹² m² 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 ∼560% enhancement in power density (4.5 μW 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.