Sol–gel synthesized BiFeO3 nanoparticles: Enhanced magnetoelelctric coupling with reduced particle size

• Particle size effects on magnetoelectric coupling in BiFeO3 nanoparticles.
• Growth mechanism of synthesized nanoparticles.
• Well corroborating dielectric and ferroelectric studies.
• Enhanced magnetic, dielectric, polarization and applied electric field values.

The present study reports the effect of particle size on magnetic, electrical and magnetoelectric properties of BiFeO3 nanoparticles prepared by the sol–gel method. Structural analysis revealed rhombohedral phase of BiFeO3 nanoparticles. Varying calcination temperature successfully tailored their size in the range 27–153 nm. The magnetic measurement confirmed enhanced ferromagnetism with reduced particle size, thereby revealing increase in suppression of spin spiral structure. Increasing density of uncompensated spins with reduced particle size enhances exchange bias. Electrical analyses-dielectric and ferroelectric-reveal decreasing losses with particle size, which results in enhanced dielectric constant and polarization values. Magnetic field dependent polarization substantiates the presence of magnetoelectric coupling. More the particle size reduction more the spin spiral suppression, and magnetic moments being oriented perpendicular to the ferroelectric axis [111], there results maximum polarization and subsequently, maximum magnetoelectric coupling.