Dielectric, strain engineering and microstructural studies of La modified (Bi0.5Na0.5)0.94 Ba0.06TiO3 relaxor ferroelectrics

A series of lead-free [(Bi0.5Na0.5)0.94 Ba0.06](1-x)LaxTiO3 (abbreviated as BNBTLa) with x = 0, 0.01, 0.02, 0.03 and 0.04 piezoelectric compound were synthesized using solid solution method. The structure, electromechanical and electrical properties were studied in detail. X-ray diffraction (XRD) analysis confirmed a rhombohedral symmetry for undoped, while La-doped compositions displayed a pseudocubic phase. The field-emission scanning electron microscopy (FE-SEM) of BNBTLa compound presented a decrease in grain size from 1.01 mu m (x = 0), to 0.82 mu m (x = 0.04). The ferroelectric-relaxor transition temperature (TF-R) shifted down to room temperature and the diffusivity (gamma) values ranged between 1 and 2. The P-E hysteresis loops profile became slimmer with the doping of La contents with reduction in remnant polarization Pr and coercive field (EC). A normalized strain of 485 pm/V was found for the sample x = 0.03. These characteristics of the BNBTLa system signified a transition from the ferroelectric to the relaxor phase. Therefore, the prepared ceramics offered extendable availability for environmental friendly capacitors, sensors and actuators.