Enhancement of dielectric and magnetic properties in phase pure, dense BiFeO_3 nanoceramics synthesized by spark plasma sintering techniques

摘要

Phase pure, dense BiFeO3 (BFO) ceramics with average grain sizes of 110 nm, 450 nm, and 1.15 A mu m 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 H (EB) = 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 A mu m). The calculated activation energies (E (a)) and X-ray photoelectron spectroscopy analyses revealed the existence of different types of defects in BFO ceramics with different grain sizes.