Characterization of Bi4−xRxTi3O12 (Rx = Pr, Nd, Gd, Dy, x = 0.8) layered electroceramics by a photoacoustic method

We have carried out photoacoustic experiments to study the layered electroceramics Bi4−xRxTi3O12 (Rx=Pr, Nd, Gd, Dy), with x=0.8. Results are shown in terms of successive analyses performed on functions, PA(t, Ti), which result from the interaction of the laser beam with the crystalline lattice. Previous permittivity experiments performed in the materials suggested anomalous ferroelectric behavior. Using a pulsed Nd:YAG laser (10 Hz, 5 ns pulse width), photoacoustic experiments were run from room temperature up to 800 °C. Perturbations in the resultant correlation curves can be interpreted as the existence of a wide set of different transition temperatures in the material, such as are believed to occur in relaxors. From these experiments, we conclude that the temperature dependence of non-classical ferroelectrics can be more closely monitored.