High performance piezoelectric composite fabricated at ultra low temperature

This work presents the next leap in piezoelectric all-ceramic composites fabricated at ultra low temperatures. The “Upside-down” composite method is further developed and instead of the water-soluble lithium molybdate used in our earlier study an organotitanate based precursor gel is used as a binder. Utilizing heat and pressure the precursor transforms into titanium oxide which together with lead zirconate titanate particles forms a high-performance piezoelectric composite. The two-step fabrication method is based only on mixing and uniaxial hot-pressing sequences. The all-ceramic samples are fabricated at ultra low temperatures 275–350 °C with exceptionally high fractions of filler (filler to matrix 84:16 vol ratio) resulting in low porosity and showing excellent dielectric and piezoelectric properties. The charge coefficient d₃₃ ∼150 pC N⁻¹ and the voltage coefficient g₃₃ ∼52 mVm N⁻¹ obtained with the developed composite outperforms many other known composites (80% and 70% higher than achieved with lithium molybdate bound upside-down composite respectively) and are comparable even to some bulk piezoceramics and low permittivity polymer-ceramic piezocomposites. The sensor properties of the developed composite and the feasibility of the material from the application point of view are successfully demonstrated by utilizing sample elements in a charge mode acceleration sensor and sensitivities comparable to commercial devices are achieved.