Dielectric properties and relaxor behavior of a new (1-x)BaTiO3-xBiAlO3 solid solution

A new lead-free perovskite solid solution of (1-x)BaTiO3-xBiAlO(3) (x=0.02, 0.05, 0.10, and 0.15) that exhibits ferroelectric properties and relaxor behavior has been synthesized by solid state reactions. X-ray diffraction patterns show a transformation from the tetragonal symmetry into a rhombohedral symmetry as a result of the substitutions of Bi3+ on the A site and Al3+ on the B site in the crystal lattice of BaTiO3. The temperature and frequency dependences of the dielectric constant indicate a crossover from a normal ferroelectric to relaxor behavior. The degree of deviation from the Curie-Weiss law is found to increase with the increasing amount of BiAlO3. The high-temperature slope of the dielectric peak for x=0.05, 0.1 and, 0.15 can be well described by a Lorenz-type relation. Typical relaxor behavior is observed for x=0.15 with the temperature of the dielectric peak T-m=360 K at 1 kHz, while ferroelectric hysteresis loop is displayed at room temperature. This suggests that the long-range polar order from the end member BaTiO3 persists and coexists with polar nanoregions induced by the chemical disorder following the coupled substitutions in the solid solution. (c) 2008 American Institute of Physics.