IMF2017

The (Bi_1/2Na_1/2)TiO₃-BaTiO₃ system (BNT-BT) is a promising lead-free material, which has been extensively studied concerning its piezoelectric properties. It exhibits complex dielectric behaviors, including the transformation from ferroelectric to antiferroelectric phase on heating. The present paper shows the structural, dielectric and ferroelectric hysteresis analysis on (Bi_0.5Na_0.5)_0.92Ba_0.08-3x/2La_xTiO₃ (x = 0, 1, 2 and 3 at%) ceramics. Both antiferroelectric-tetragonal (P4bm) and ferroelectric-rhombohedral (R3c) phases co-exist at room temperature. Scanning Electronic Microscopy (SEM) micrographs and energy dispersive spectroscopy analysis suggest that a homogenous solid solution has been formed and that the La³⁺ ions have been incorporated into the BNT-BT lattice. The dielectric behavior shows two phase transitions, one of seems to exhibit typical relaxor characteristics. The La³⁺ ions content shows an important influence on the dielectric parameters. The electric field dependence of the polarization (P-E, hysteresis loops) is also influenced by the lanthanum concentration. For x = 0.01, P-E curve exhibits double-like hysteresis loops suggesting a higher stability of the antiferroelectric phase (AFE). For the other ceramics, squareness-like P-E curves have suggested a higher ferroelectric phase (FE) stability. Antiferroelectric loops are obtained on heating for all compositions.