Recent advances in ceramic-polymer composite electrets

Recent work on ceramic-polymer composites for piezoelectric and pyroelectric applications is presented with special regard to the production and characterisation of new composite materials as well as two new applications of these composite materials. One of these composites is made using ceramic powders obtained using the sol-gel technique. This technique allows a better control of the stoichiometry as well as a lower temperature of crystallisation as compared with the conventional mixed oxides route. A better control of powder morphology also produces ceramic grains in the sub-micron range enabling the production of nanocomposites with electro-active properties. A second type of composite is reported using high temperature polymer PEEK, thus extending the temperature range of common electroactive composite materials. Finally the use of these materials is demonstrated in two piezoelectric applications, an angular acceleration accelerometer and an acoustic emission sensor.