Effect of La A-site doping on the electro-induced strain and conductivity mechanism of BiFeO3-BaTiO3 lead-free piezoelectric ceramics

The poor electrical properties and high leakage current of BiFeO 3 -BaTiO 3 -based ceramics are the main reasons that hinder their application. A two-step sintering method prepared the 0.68Bi 1-x La x (Fe 99.8% Sb 0.2 % )O 3 -0.32BaTiO 3 ceramics (x = 0, 0.005, 0.01, 0.015, abbreviated as BL x FS-BT). The surface morphology and properties of the ceramic were observed and tested using different techniques. La ion doping significantly affects the crystal structure, leakage current, and the electro-induced strain of the BL x FS-BT ceramics. BL 0.005 FS-BT ceramics achieve 0.198 % unipolar electro-induced strain and 396 pm/V inverse piezoelectric coefficient under a 50 kV/cm electric field, and they can maintain good temperature stability at high temperatures. A large strain of 0.43 % was obtained at 150 °C. The inhibition effect of La ion on Fe valence and oxygen vacancy formation also greatly improves the insulation performance of ceramics. This work shows that BF-BT-based ceramics via ion substitution defect engineering effectively enhance electrical and insulating properties.