Upside - down composites: Fabricating piezoceramics at room temperature

摘要

Piezoelectric materials have a multi-billion dollar impact on the electromechanical transducers market. Their conventional synthesis includes a sintering step (at over 1000 degrees C) that often hampers direct integration into monolithic devices and confines their applications to heterostructures made using tedious multi-step assembly or to composites with poor electromechanical behavior. Here, we demonstrate a new and easy to scale method for the integration of piezoelectric ceramics at ultra-low temperatures without compromising their functionality. We show that all-ceramic "upside-down" composites with exceptionally high fractions of piezoelectric filler ((similar to)75 vol. %) and low porosity can be achieved using aqueous dispersion of lithium molybdate as a binder. The method is based only on coating, mixing, moulding and drying sequences. The measured piezoelectric charge coefficient, d(33) (similar to)84 pC.N-1, outperforms any other known composite, whereas the voltage constant, g(33) (similar to)33 mV m.N-1, competes with bulk materials, thus paving the way for versatile applications not previously considered.