Recycling hazardous and energy-demanding piezoelectric ceramics using an oxide–halide perovskite upside-down composite method

Piezoelectric ceramics are widely employed in electromechanical coupling components such as sensors, actuators, and transducers owing to their excellent performance, cost-effectiveness, versatile shapes and configurations, and generous chemical/functional tuneability. However, most piezoceramics contain a significant amount of the hazardous and toxic element Pb, which is considered unsustainable. Although more environmentally friendly Pb-free counterparts have been developed, production of both Pb-containing and Pb-free piezoceramics still demands high energy consumption. On the other hand, retired and rejected piezoceramics are not properly recycled, leaving a large ecological footprint for the piezoelectric industry. Thus, there is a need for proper recycling methods which give wasted piezoceramics a second life at only a marginal energy cost, so that the energy and environmental footprints are minimized before the piezoceramics are permanently disposed of. This work demonstrates the fabrication and use of oxide–halide perovskite composites to recycle piezoceramics. The composites consist of oxide perovskite piezoceramic particles as the fillers that mimic crushed/recycled piezoceramics and an organometal halide perovskite, PTMA–CdCl3 (PTMA is C6H5N(CH3)3), as the matrix/binder. The composites consume only about 1% of the energy budget required for making new equivalent piezoceramics whilst retaining comparable capabilities for sensing applications. The results suggest that such a recycling method is applicable to a broad range of piezoceramics, providing an incentive to possibly extend the method for simultaneously recycling other oxide and halide perovskite materials and components in the future.