Synthesis and Characterization of La-Doped BNBT Lead-Free Ceramics with Enhanced Piezoelectric and Dielectric Properties

The present work deals with the synthesis of [(Na_0.5 Bi_0.5)_0.94 Ba_0.06]_1-x La_x TiO₃ with the method of conventional solid-state reaction with the composition of BNLBT in which the “x” has value 0.02. These ceramics show large piezoelectric and dielectric properties with the addition of La into BNT-BT. X-ray diffraction analysis for 0.02mol% shows a single perovskite rhombohedral structure without other phases. The surface morphology is examined by FE-SEM, where the average grain size is calculated at 1.08 to 2.02 µm. The maximum dielectric constant observed at a frequency of 1MHz was 3980 for a ratio of 0.02 mol%, while T_d shifted to almost room temperature. A low loss factor (tanδ) of less than 10% was observed for 0.02mol% under 1 kHz, 10 kHz, and 100 kHz. For BNBT-3La, the huge maximum strain S_max is 0.27% with a high normalized strain d*₃₃= 387 pm/V under 70 kV/cm at room temperature. A thin P-E loop was obtained for BNBT-La 0.02mol%, from the P-E loop, huge remnant polarization P_r= 20.91 µC/cm², P_max= 42.58 µC/cm^2, and E_c= 16 kV/cm was observed.