Center Smart Materials and Adaptive Systems CeSMACeSMA has developed a variety of piezoceramic nanoparticles. Similar to piezoceramic bulk materials or layers, piezoceramic particles are ferroelectric materials that generate charges under pressure.
CeSMA focused on particles with a diameter of 100 – 500 nm. This particle size takes into account that particles with a size larger than 100 nm are less critical than smaller particles. In addition, due to the large surface-to-volume ratio, there are a number of surface-ion induced disturbances that can degrade the piezoelectric behavior. Although lead-containing particles have been synthesized as a high performance reference material, lead-free compositions are developed as well.
The piezoceramic particles can be integrated into passive or functional matrices, and the resulting composites can be applied as layers with layer thicknesses down to 5 - 50 µm. The matrices allow to use alternative low-temperature process technologies in contrast to the manufacture of piezoceramic layers that have to be sintered at temperatures > 400 °C.
Instead of passive matrices (such as elastomers), piezoceramic nanoparticles can be integrated into piezopolymers as well. In this case, it is possible to reduce the cross sensitivity between pyroelectric (thermally generated charges) and piezoelectric (charges generated by mechanical forces) behavior using a suitable poling technique.