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

Tactics of particle size for enhanced multiferroic properties in nanoscale Ca‐doped BiFeO3

“…The observed monotonic increase in M s with the reduction in particle size of Ca-doped BiFeO 3 nanoparticles is quite obvious. The increasing surface to volume ratio with decreasing particle size increases the contribution of uncompensated magnetic spins and thus enhances the magnetisation [13]. The observed magnetisation values of Ca 6 and U 4 nanoparticles also corroborate this finding.…”

“…Firstly, due to the grain size confinement effect, long-range spin cycloidal structure of BiFeO 3 gets partially destroyed as its size (31 nm; TEM) being less than its incommensurate period of 62 nm thereby, results in ferromagnetism [6]. Secondly, small antiferromagnetic nanoparticles possess measurable magnetic moment [13]. An antiferromagnet consists of spin sublattices which have intra-ferromagnetic and inter-antiferromagnetic interactions.…”

“…The dispersions observed in the dielectric behaviour unveil the presence of space charges. In BiFeO 3 , oxygen and bismuth vacancies, lattice distortions and defects act as sources of space charges [13]. These space charges are able to follow the applied field at lower frequencies but unable to do so at higher frequencies, subsequently, the dielectric constant decreases [36].…”

“…Also, various polarisations (electronic, atomic, ionic and interfacial) contribute towards dielectric constant. However, only electronic polarisation contributes towards dielectric constant at higher frequencies thereby, resulting in its decrease [13].…”

“…Studies of alkaline earth metal substituted BiFeO 3 nanoparticles abound in literature, which demonstrate improvement of magnetic and dielectric properties [7][8][9][10]. It has been revealed that reduction of size to nanoscale [5][6][7][8][9][10][11][12][13] and alkaline earth metal ion substitution [8][9][10][11] efficiently overcomes these problems. A lot of reports studying the influence of size on multiferroic properties of BiFeO 3 are available [5,6,[11][12][13].…”