Characterization of Bi(0.5)Na(0.5)Tio(3)-PbTiO3 dielectric materials

Bi0.5Na0.5TiO3 (BNT) modified with Pb showed an increased and broadened dielectric constant and limited grain growth. Pb also lowered the first transition temperature. The phases of BNT were confirmed to be ferroelectric at room temperature which transformed to antiferroelectric above 220 degrees C. When BNT was doped with 10% Pb, the first transition decreased to 140 degrees C and abruptly disappeared in the composition with 17% Pb. The crystal structure of 17%-Pb-doped BNT at room temperature is tetragonal, which differs from the rhombohedral structure at lower Pb contents. Thus, the phase boundary between rhombohedral and tetragonal ferroelectric phase was determined to be between 15% to 17% Pb in this study.