Enhancement of dielectric and magnetic properties in phase pure, dense BiFeO 3 nanoceramics synthesized by spark plasma sintering techniques

Phase pure, dense BiFeO3 (BFO) ceramics with average grain sizes of ~ 110 nm, ~ 450 nm, and ~ 1.15 µm were fabricated by spark plasma sintering method. BFO ceramics exhibited grain-size-dependent magnetic properties, which ascribed to the antiferromagnetism–ferromagnetism (AFM–FM) transition. For BFO nanoceramics (~ 110 nm), such transition was much significant, and contributed to a large exchange bias field of HEB = 500 Oe at 5 K. In addition, BFO nanoceramics (~ 110 nm) exhibited lower leakage current and higher resistivity compared to the larger-grained BFO ceramics (~ 450 nm and ~ 1.15 µm). The calculated activation energies (Ea) and X-ray photoelectron spectroscopy analyses revealed the existence of different types of defects in BFO ceramics with different grain sizes.