Piezoelectric properties of SrBi2Nb2O9 textured ceramics

The textured ceramics of the bismuth layer structured ferroelectrics SrBi2Nb2O9 (SBN)-type compound were fabricated by the templated grain growth (TGG) method, and their characteristics and piezoelectric properties were studied. Platelike particles with a large shape anisotropy, which were needed as template particles in the TGG process, were obtained for the composition with 10% Nd substitution on the Sr site of SBN. Highly (00l) textured Sr0.9Nd0.1Bi2Nb2O9 (SNBN) ceramics were successfully obtained using the TGG process with platelike particles, and the orientation degree of the textured ceramics was 96%. The electromechanical coupling factor of the 96% orientation degree textured ceramics in the thickness shear vibration mode was three times as large as that for the randomly oriented ceramics. The temperature coefficient of the resonant frequency (TCF) of the textured ceramics was +20.9ppm/degrees C, whose absolute value was two-thirds of that of the randomly oriented ceramics. The resonant frequency of the textured ceramics increased with temperature, while the resonant frequency of the randomly oriented ceramics decreased with increasing temperature. This result indicated the possibility of obtaining an excellent TCF by the optimization of grain orientation. Therefore, textured ceramics with orientation degrees from 54% to 96% were prepared using template particles of different average diameters, and. an excellent TCF of -0.4ppm/degrees C was obtained for the specimen with an orientation degree of 76%.