Aurivillius-type ceramics, a class of high temperature piezoelectric materials: Drawbacks, advantages and trends

The obtention of reliable and high performance piezoelectric ceramics for uses at high temperatures is still an open issue in the field of electroceramics. The materials used nowadays for such applications present limitations due to different causes: low piezoelectric coefficients, difficulties in processing that lead to the necessary use of single crystals, high cost of raw materials and more. In this sense, an increasing interest in materials with the so-called Aurivillius-type structure has occurred during recent years, due to their relatively high piezoelectric coefficients and high ferro–paraelectric phase transition temperature. However, some difficulties must be overcome, such as processing for obtaining highly dense ceramics and determining their real piezoelectric behaviour at high temperature. In this work, a review of the processing and properties of ceramics with this structure is shown. Effects of the use of precursors obtained by an alternative route mechanical activation on the microstructure are explained. A complete piezoelectric characterization at working temperatures (>300 °C), barely found in the literature, is also shown. The effects of trapped charges in the dielectric permittivity and in the piezoelectric radial resonance are also discussed.