Enhanced piezoelectric properties of Aurivillius-type sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) by B-site manganese modification

The Aurivillius-type bismuth layer-structured ferroelectrics (BLSFs) sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15, NLBT) polycrystalline ceramics with 0.0-0.4 wt% MnO2 were synthesized using conventional solid-state processing. Phase analyses were performed by X-ray powder diffraction (XRPD), and the microstructural morphology was assessed by scanning electron microscopy (SEM). The dielectric and piezoelectric properties of the manganese-modified NLBT ceramics were investigated in detail. The results show that manganese is very effective in promoting the piezoelectric activities of NLBT ceramics, and the reasons for piezoelectric activities enhancement by manganese modification are explained. The NLBT ceramics modified with 0.2 wt% MnO2 (NLBT-Mn2) possess good piezoelectric properties, with a piezoelectric coefficient d(33) of 28 pC/N. This value is the highest value among the modified NLBT-based piezoelectric ceramics examined. The temperaturedependent dielectric spectra show that the Curie temperature T-c of the manganese-modified NLBT ceramics is slightly higher than that of the pure NLBT ceramics. Thermal annealing analysis revealed that the manganese-modified NLBT ceramics possess good thermal stabilities up to 500 degrees C. These results demonstrate that the manganese-modified NLBT ceramics are promising materials for high temperature piezoelectric applications. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.