LiNbO3-induced phase structure evolution and improved piezoelectric properties in BiFeO3–BaTiO3 ceramics.

Eco-friendly (0.73- x)Bi 1.05 FeO 3 - x LiNbO 3 -0.27BaTiO 3 ternary ceramics were designed and prepared via a solid-state sintering route. Based on the X-ray diffraction results and Rietveld refinement, it was found that the structure of the ceramics transformed from rhombohedral to tetragonal symmetry with the addition of LiNbO 3 , and at x = 0.003, there existed a morphotropic phase boundary separating the two phases. Near the phase boundary, the largest values were achieved for the piezoelectric constant d 33 and planar electromechanical coupling coefficient k p , being 180 pC/N and 0.27, respectively. Due to the addition of LiNbO 3 , the grain size tended to become smaller. Additionally, the ceramics were transitioned from normal to relaxor ferroelectrics with increasing x. Despite the fact that the LiNbO 3 addition would result in a gradual decrease of Curie temperature, a relatively high Curie temperature (535 °C) was still maintained at x = 0.003, the phase boundary composition, which also showed good temperature stability of piezoelectric properties. These experimental results can provide a reference for the practical applications of high-temperature lead-free ceramics. [ABSTRACT FROM AUTHOR]