Structure, Ferroelectric, Piezoelectric, and Ferromagnetic Properties of BiFeO 3 ‐BaTiO 3 ‐Bi 0.5 Na 0.5 TiO 3 Lead‐Free Multiferroic Ceramics

Lead‐free multiferroic ceramics of BiFeO 3 ‐ BaTiO 3 ‐ Bi 0.5 Na 0.5 TiO 3 have been prepared by a conventional ceramic technique. The microstructure, multiferroic, and piezoelectric properties of the ceramics have been studied. The ceramics sintered at 1000°C for 2 h possess a pure perovskite structure and a morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.02. After the addition of Bi 0.5 Na 0.5 TiO 3 , two dielectric anomalies are observed at high temperatures ( T m ~ 510°C–570°C and T 2 ~ 720°C). The phase transition around T m becomes wider gradually with increasing x . The ferroelectricity, piezoelectricity, and ferromagnetism of the ceramics are significantly improved after the addition of Bi 0.5 Na 0.5 TiO 3 . High resistivity (~1.3 × 10 9 Ω·cm), strong ferroelectricity ( P r = 27.4 μC/cm 2 ), good piezoelectricity ( d 33 =140 pC/N, k p = 31.4%), and weak magnetic properties ( M r =0.19 emu/g) are observed.