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The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO3 nanoparticles has been studied. A sol-gel method was employed for the synthesis of nanoparticles and their particle size was tailored by varying the calcination temperature. Structural analysis revealed a rhombohedral distortion induced by Ca-substitution. The broadening of diffraction peaks with decreasing calcination temperature was indicative of reduction in crystallite size. The morphological analysis revealed the formation of agglomerated nanoparticles having average particle size ranging from 10-15 and 50-55 nm for C4 and C6, respectively. The agglomeration is attributed to high surface energy of nanoparticles. Ferromagnetism has been displayed by all the synthesized nanoparticles. Enhancement of saturation magnetization with Ca-substitution is attributed to suppression of spin cycloid structure by the reduction in size, lattice distortion and creation of oxygen vacancies by the substitution of divalent ion at trivalent site. Further, this value increases as a function of decreasing particle size. Strong particle size effects on magnetic properties of the synthesized nanoparticles are owed to increasing surface to volume ratio. All these observations are indicative of strong dependence of multiferroism on particle size. [ABSTRACT FROM AUTHOR]

Multiferroic are the materials possessing more than one ferroic orders are the need of present technology. In this context pure and 20 % Ba doped-BiFeO3 nanoparticles have been synthesized by sol gel method. Effect of reduced size and Ba doping on multiferroic properties of BiFeO3 nanoparticles have been investigated. Structural study carried out using x-ray diffraction (XRD) reveals that pure BiFeO3 nanoparticles possess rhombohedral structure; but 20 % Ba doping in host BiFeO3 leads to structural distortion. Magnetic study confirms that the synthesized samples exhibit ferromagnetic behaviour, and the value of saturation magnetization, increased with doping of Ba. Electrical characterization carried out using polarization versus electric field loop (PE) and leakage current density versus applied electric field (JE) clearly confirms that doping of Ba reduced leakage and results in good ferroelectric material. Synthesized materials simultaneous exhibit ferromagnetic and ferroelectric behavior thereby confirms its multiferroic nature. [ABSTRACT FROM AUTHOR]