Enhancing piezoelectric coefficient d33 in LiF-doped BaTiO3 ceramics by optimizing excess Ba content

Influence of excess Ba content (x) on phase structure, microstructure and electrical properties of normally sintered Ba1+xTiO3-0.04LiF (0 ≤ x ≤ 0.040) ceramics at 1100 °C was investigated. A pure perovskite structure consisting of tetragonal and orthorhombic (O–T) symmetries was attained as x < 0.035. The grain was first refined and then grown with increasing x, being opposite to the variation tendency of the piezoelectric property. The high piezoelectric coefficient d33 = 340 pC/N was achieved at x = 0.025, which is attributed to the small average grain size about 10 μm and coexisting O–T phase. The Curie temperature (TC) increases as x increases and achieved maximum value 111 °C at x = 0.040. The high piezoelectricity suggests that Ba1+xTiO3-0.04LiF ceramics have good prospects to replace lead-based piezoceramics.