Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

Abstract

Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0.9Ba0.1FeO3 nanoparticles of different sizes ranging from ∼ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe 2+ state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO3 nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi0.9Ba0.1FeO3 nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ∼ 49 nm Bi0.9Ba0.1FeO3 nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO3.

Influence of Ba and Mo co-doping on the structural, electrical, magnetic and optical properties of BiFeO3 ceramics

“…The source of Mo 6+ used in this study is MoO 3 powder which have a melting temperature of 795°C only and leads to select low calcination/sintering temperature for this case. As several previous studies concluded that sintering below 800°C results in impurity phases in BFO, it is therefore a tough task to zero out the possibility of impurity formation [11]. However, possible impurities and their effects on the properties of BFO is explained further in this study.…”

“…In our study, we tried to analyze structural and morphological changes in details due to Ba 2+ and Mo 6+ co-doping in BFO. Previous studies show that Ba 2+ doping creates a weak ferromagnetism in BFO, though creates significant oxygen vacancies [11]. So, it can be expected that Mo 6+ doping in Ba-doped BFO could significantly suppress the oxygen vacancy and thus improve dielectric property.…”

Dy doped BiFeO 3 : A bulk ceramic with improved multiferroic properties compared to nano counterparts

“…In previous investigations, we also observed improved structural and magnetic properties for Gd doped and Gd-Ti co-doped BFO nanoparticles compared to their corresponding bulk ceramics [16], [17]. Withstanding the fact that improved multiferroic properties of undoped and cation doped BFO nanoparticles were reported in various investigations [18]- [22], the associated jeopardy was that rigorous synthesis procedure had to be adopted to obtain nanoparticles with sizes less than 62 nm.…”

“…The temperature dependent magnetization measurements were investigated both at zero field cooling (ZFC) and field cooling (FC) processes. To measure electrical properties of nanoparticles, pellets were prepared by pressing the powders using a hydraulic press and annealing at 750 o C with high heating rate (20 o C/min) [22]. A ferroelectric loop tracer in conjunction with an external amplifier (10 kV) was used to trace the leakage current density and ferroelectric polarization of the pellet shaped samples.…”

Colloidal Energetic Systems

“…This case is also the more complex one to deal with, as each intrinsic property brings along mutual effects that we must be able to control and eventually exploit, as shown in Figure . To offer a clear and possibly fully controllable response to both the electric and magnetic field, at least three strategies are considered: 1) using an FF, where the magnetic NPs have been capped with a charged surface layer, for example an organic acid; 2) using a multiferroic colloid, where its constituent NPs display both ferroelectricity and ferromagnetism; 3) using a Janus system (in which each particle has two properties), where each spherical micro/NP has two moieties, one ferroelectric and the other one FM …”