Multiferroic properties of Bi 0.8 Dy 0.2−x La x FeO 3 nanoparticles

Bi0.8Dy 0.2−x LaxFeO3 (BDLFOx) (x = 0, 0.10 and 0.20 respectively) nanoparticles were prepared by the ethylene glycol based sol–gel method. The influence of the average radius and the effective magnetic moment of Bi-site ion on the structure, magnetic and dielectric properties, and the effective magnetic susceptibility of BDLFOx nanoparticles was investigated. All the samples were indexed to the orthorhombic structure based on the results of x-ray diffraction. The grain size of the samples increased with the increase in Bi-site ionic average radius. The magnetization of the samples was found to decrease with the effective magnetic moment of Bi-site ion decreasing. The dielectric constant and loss were improved when the Bi-site ionic average radius decreased and the effective magnetic moment of the Bi-site ions increased. The enhanced magnetization M and the polarization P in nanoparticles made the effective magnetic susceptibility of the samples greatly enhanced, in particular for the sample of x = 0. Therefore we concluded that the small amount of substitution of Bi 3+ ions by trivalent rare-earth ions with a smaller ionic radius than Bi 3+ ion and a high magnetic moment in the nano-system was a way to improve the multiferroic properties of BiFeO3. (Some figures in this article are in colour only in the electronic version)