Microstructure, enhanced electric and magnetic properties of Bi0.9La0.1FeO3 ceramics prepared by microwave sintering

Abstract

Bi0.9La0.1FeO3 (short for BLFO) ceramics was fabricated by conventional solid-state reaction and microwave sintering. Effects of microwave sintering temperature on microstructure, electric and magnetic properties have been systematically investigated. The XRD results indicate that BLFO ceramics sintered at 800 °C and 820 °C are single rhombohedral distortion perovskite phase, and there is small amount of secondary phase (Bi2Fe4O9) in the ceramic sample sintered at 780 °C. As microwave sintering temperature rises, the densification of BLFO ceramics enhances and the grain size increases, but the homogeneity of grain becomes worse. Microwave sintering temperature has little effect on room-temperature dielectric constant. The leakage current density decreases with the rise of sintering temperature, which is closely related to enhanced densification. The leakage mechanism of BLFO ceramics changes from bulk-limited Poole-Frenkel emission to space-charge-limited bulk conduction as sintering temperature rises. The remnant polarization of BLFO ceramics sintered at 820 °C is much higher than that of the samples sintered at 800 °C and 780 °C, and the coercive electric field changes little with sintering temperature. The results indicate the higher sintering temperature is benefit for the ferroelectricity of BLFO ceramics. The magnetic hysteresis loops of BLFO ceramics indicate that the ceramic samples sintered at 800 °C and 820 °C show a typical ferromagnetic behavior at room temperature. Compared with BLFO ceramics sintered at 800 °C, the spontaneous magnetization and saturation magnetization of BLFO ceramics sintered at 820 °C are higher, and its remnant magnetization and coercive magnetic field are lower.