Enhanced dielectric and ferroelectric responses in La3+/Ti4+ co-substituted SrBi2Ta2O9 Aurivillius phase.

The molten salt technique was employed to prepare the Aurivillius phases SrBi 2 Ta 2 O 9 (SBT) and Sr 0.9 La 0.1 Bi 2 Ta 1.9 Ti 0.1 O 9 (SLBTT). The XRD data and the Le Bail refinement approach demonstrate that both samples formed the double-layer Aurivillius phase with the orthorhombic A 2 1 am structure successfully. The SLBTT cell volume is smaller compared to SBT with the substitution of smaller La3+ and Ti4+ ions and the increased size of the plate-like grains. FTIR analysis indicates the two local arrangements of Ti4+ at the B -site to form Ti–O–Ti and Ti–O–Ta bonds. Changes in the structural properties due to La3+ and Ti4+ substitution are reflected in the electrical properties. The higher ferroelectric transition temperature (T c) of 455°C with the diffused phase transition behavior (DPT) was obtained in SLBTT. The unsaturated hysteresis loop of SLBTT obtained the ferroelectric remnant polarization (P r) of 0.43 μC/cm2 and the coercive field (E c) of 110.6 kV/cm, respectively. The enhanced ferroelectric characteristic as well as a higher bandgap (E g) that is driven by the substitution of variable smaller cations. [ABSTRACT FROM AUTHOR]