Dielectric properties, thermal decomposition and related aspects of BiAlO3

BiAlO3, prepared under high-pressure and high-temperature conditions has a rhombohedral perovskite structure ( R 3 c with a = 5.3747 ( 4 )  Å and c = 13.391 ( 1 )  Å) and decomposes around 550 ∘C to form the intermediate Bi2Al4O9 phase along with the Bi 26 − x Al x O 40 − y and Al2O3. Above 580 ∘C, the intermediate phase changes into the Bi 26 − x Al x O 40 − y . Dielectric measurements show an anomaly at the decomposition temperature and hysteresis at room temperature with a maximum polarization of ∼16 μC/cm2. Raman scattering measurements suggest softening of optical phonon modes, and are consistent with the occurrence of thermal decomposition of the rhombohedral phase to form the thermodynamically stable phase.