Effect of Ba–Nb co-doping on the structural, dielectric, magnetic and ferroelectric properties of BiFeO3 nanoparticles

Abstract Multiferroic BFO nanoparticles of compositions Bi 1− x Ba x FeO 3 and Bi 1− x Ba x Fe 1− x Nb x O 3 ( x= .05 and .1) have been synthesized using sol–gel followed by an auto-combustion route. The effect of Ba–Nb co-doping on structural, magnetic, dielectric, leakage current and ferroelectric properties has been investigated. XRD patterns confirm the rhombohedral phase for all the samples in which traces of pseudo-cubic phase have been observed as a result of co-doping. The residual and saturation magnetization get increased significantly, which is attributed to a decreased degree of structural distortion and smaller particle size due to co-doping. Dielectric studies show strong dispersion for Ba-doped samples while Ba–Nb co-doped samples are nearly frequency independent. Furthermore, dielectric constant ( e ∞ ) at higher frequencies increases with doping level whereas dielectric loss decreases due to reduction in defect centers by co-doping. Temperature dependent dielectric analysis reveals strong anomaly near magnetic transition ( T N ), signifying magnetoelectric coupling for all the samples. Leakage current has been decreased to 2–3 orders of magnitude and conductivity behavior has come close to ohmic type for 10% Ba–Nb co-doped sample, which suggested a significant reduction in oxygen vacancies. The saturation level of ferroelectric loop is also improved with doping level and remnant polarization increases from 1.28 μC/cm 2 for 5% Ba-doped to 3.24 μC/cm 2 for 10% Ba–Nb co-doped sample. Hence, Ba and Nb co-doped BFO nanoparticles can be used as a promising candidate for magneto-electric applications.