BiFeO3 Ceramics: Structure–Property Relationships and Doping Strategies

Bismuth ferrite (BiFeO3, BFO) is a lead-free perovskite that combines robust ferroelectricity and antiferromagnetism at room temperature, making it one of the most extensively studied room-temperature multiferroics for spintronics, sensors, and multifunctional devices. In bulk ceramics, however, Bi volatility, oxygen-vacancy-driven leakage, and parasitic phases complicate synthesis and obscure intrinsic ferroic response. This review critically revisits the fundamental physical properties of bulk BiFeO3 ceramics by elucidating the relationships between crystal structure, defect chemistry, processing, and ferroic functionalities. Particular emphasis is placed on the evolution of the understanding of the intrinsic ferroelectric, magnetic, dielectric, and magnetoelectric properties of bulk BiFeO3, highlighting the landmark experimental and theoretical studies that have shaped the current picture of this material. The review further examines A-site (Bi) and B-site (Fe) substitutions and selected co-doping strategies, assessing how they modify structural stability and ferroic behavior. Finally, representative performance benchmarks for undoped and doped bulk ceramics are compared, and the remaining challenges toward achieving reproducible room-temperature magnetoelectric functionality are critically discussed. Overall, this review provides a unified framework linking crystal chemistry, processing methods, microstructure, doping engineering, and ferroic functionalities, offering practical guidelines for the rational design of high-performance BiFeO3-based bulk ceramics for next-generation multifunctional devices.