Chemical Prehistory Effects on the Room‐Temperature Magnetic Response of BiFeO 3 Particles

Multiferroic BiFeO 3 nanoparticles with tunable average crystallite sizes from 40 to 150 nm were synthesized via the solution combustion method. Crystallite size control was achieved through two distinct routes: sequential high‐temperature annealing and variation of the fuel‐to‐oxidizer ratio (ϕ) in the precursor. The magnetic properties exhibited a strong dependence on the chemical prehistory of the samples. For the annealed series, the room‐temperature magnetic response follows a modified core‐shell model featuring an effective surface shell thickness of 1–4 nm. Conversely, the samples synthesized by varying ϕ demonstrated an exponential magnetization decay with size. Identifying these magnetization models enables precise performance tailoring in multiferroic materials for advanced magnetoelectric applications.