Enhanced insulation and piezoelectric properties of 0.57(Bi 0.8 La 0.2 )FeO 3 ‐0.43PbTiO 3 solid solutions with Fe addition

Abstract 0.57(Bi 0.8 La 0.2 )FeO 3 ‐0.43PbTiO 3 ‐ x mol%Fe 2 O 3 ceramics (BLF‐PT‐ x Fe, x = 0, 0.025, 0.05, 0.125, and 0.25) were prepared by the conventional solid‐state reaction method. X‐ray diffraction (XRD) reveals that all samples display the perovskite structure with a coexistence of tetragonal (T) phase and rhombohedral (R) phase, while the incorporation of Fe promotes the phase transition from T to R. Scanning electron microscopy (SEM) images show that all samples are well crystallized and their grain size increases noticeably with the increase of Fe content. X‐ray photoelectron spectroscopy (XPS) results indicate that Fe doping significantly inhibits the formation of oxygen vacancies, thereby improving insulation of BLF‐PT‐ x Fe ceramics. Interestingly, the Curie temperature of BLF‐PT‐ x Fe is around 330°C, little changing with the variation of Fe content. However, the depolarization temperatures of BLF‐PT ceramics with Fe are 50°C higher than that of the sample without Fe doping. The hopping of second ionized oxygen vacancies are the major carriers in the temperature range of 200°C–500°C. The optimal component of BLF‐PT‐ x Fe ceramics appear at x = 0.05, where the dielectric loss tan δ , AC resistivity (200°C), and piezoelectric coefficient d 33 could be 0.015, 7 × 10 6 Ω cm, and 245 pC/N, respectively. All these results indicate that the Fe addition is an effective method to enhance dielectric and piezoelectric properties.