Microstructure and electrical properties of Aurivillius phase (CaBi2Nb2O9)1-x(BaBi2Nb2O9)x solid solution

The microstructures and electrical properties of Aurivillius phase ferroelectric solid solutions of (CaBi2Nb2O9)(1-x)(BaBi2Nb2O9)(x) (0 <= x <= 1) have been studied. X-ray diffraction analyses revealed a bismuth layered structure for all compositions. Scanning electron microscope images showed randomly oriented and platelike grain morphology. The Curie point T-c or the maximum permittivity temperature T-m decreased with increasing x. The (CaBi2Nb2O9)(1-x)(BaBi2Nb2O9)(x) ceramics exhibited a ferroelectric-paraelectric phase transition at small x values (x <= 0.5), whereas a relaxor behavior was observed at high x values (x >= 0.8). The d(33) value of CaBi2Nb2O9 ceramics was enhanced by Ba2+ doping on the A-sites (x <= 0.3). A combination of high d(33) values and high T-c points (>700 degrees C) suggests that compositions with x <= 0.3 could be good candidates for high-temperature piezoelectric applications. The composition with x=0.8 is a relaxor ferroelectric with T-m around 320 degrees C at 1 MHz. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457229]