Ferroelectric and piezoelectric properties of Aurivillius phase intergrowth ferroelectrics and the underlying materials design

Ferroelectric and piezoelectric properties of the La-doped intergrowth Aurivillius phase ceramics Bi5-xLaxTiNbWO15 and Bi7-xLaxTi4NbO21 (x = 0.00-1.75) were studied. It was found that the La doping is in favour of the domain switching. Owing to the impact of defects, the P-E hysteresis loops of the La-doped Bi5TiNbWO15 ceramics are un-symmetrical and the piezoelectric coefficients are quite low. Enhanced ferro-/piezoelectric properties, such as 2P(r) of 24.4 mu C/cm(2) (x = 0.50) and d(33) of 16.6 pC/N (x = 0.75), were obtained in the Bi(7-x)LaxTi(4)NbO(21) ceramics. The high temperature electrical behaviour indicates that the Bi5-xLaxTiNbWO15 ceramics are semiconducting whereas the La-doped Bi7Ti4NbO21 ceramics are worthy to be further studied toward high temperature piezoelectric applications. Finally, the underlying materials design is discussed. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim