Dielectric, ferroelectric and magnetic properties of Bi(Mg,M)O3-modified (M=Hf, Ta) BiFeO3-BaTiO3 ceramics

BiFeO3 is the most typical multiferroic materials. In this paper, the effects of different types of ion replacement on the structure and properties of Bi(Mg,M)O-3 (M=Hf, Ta) modified 0.75BiFeO(3)-0.25BaTiO(3)-based ceramics were investigated. XRD and TEM analysis showed that all samples were characterized by the coexistence of rhombohedral R3c and tetragonal P4mm phases. Two dielectric anomalies were observed for all samples. Among them, the dielectric relaxation at 300 similar to 500 degrees C showed obvious frequency dispersion, which was related to the diffusion of oxygen ion vacancies. A frequency independent dielectric anomaly was detected accompanied by thermal hysteresis at around 625 similar to 650 degrees C, which indicated the first-order ferroelectric transition of all samples. Meanwhile, the ferroelectric transition temperatures of all samples hardly change, which was attributed to the fixed A-site substitution contents, indicating that the ionic species has little effect on the phase transition temperature. The leakage current of the ceramics was significantly reduced after composite ion replacement. The magnetic properties of the ceramics were significantly improved after the addition of (Mg, M) composite ions, and the magnetic properties of (Mg1/2Hf1/2)(3+)-substituted samples is better than that of (Mg2/3Ta1/3)(3+)-substituted samples. The increased magnetic properties is attributed to the suppression of the helical spin structure of the ceramic antiferromagnetic sequence by the B-site ion replacement.

Automated summary

This study investigates the effects of different types of ion replacement on the structure and properties of Bi(Mg,M)O-3 modified ceramics. The results show that the replacement of ions can significantly improve the leakage current and magnetic properties of the ceramics. Furthermore, the type of ion has little effect on the phase transition temperature.