Phase transformation behavior and dielectric characteristics of BaTi1−x(Al1/2Nb1/2)xO3 (0.01≤x≤0.40) ceramics Original Research Article

Microstructure, phase transformation behavior and dielectric properties of BaTi1−x(Al1/2Nb1/2)xO3 (0.01≤x≤0.40) ceramics were investigated. A high level of (Al1/2Nb1/2)4+ substitution for Ti4+ ions was not conducive to the stability of the perovskite structure and resulted in the formation of BaAl2O4. As x was increased, lattice constants and unit cell volume decreased, reached a minimum at x=0.10 and then increased. The BaTi1−x(Al1/2Nb1/2)xO3 ceramics at room temperature experienced a transformation from ferroelectric to paraelectric phase with increasing (Al1/2Nb1/2)4+ concentration. Meanwhile, permittivity of the BaTi1−x(Al1/2Nb1/2)xO3 ceramics was markedly reduced, while Q value was slightly increased. Frequency dispersion of dielectric peak was obviously increased as x was increased from 0.01 to 0.10. It is of great interest that a dielectric abnormity represented by a broad dielectric peak at 200–400 K was observed for the composition with x=0.40.