Synthesis, structure and magnetic ordering of the mullite-type Bi2Fe(4-x)CrxO9 solid solutions with a frustrated pentagonal Cairo lattice

Shape dependent multiferroic behavior in Bi2Fe4O9nanoparticles

Ferroelectric and magnetic properties are investigated for Bi₂Fe₄O₉nanoparticles with different shapes (cuboid and sphere-like) synthesized by hydrothermal and sol-gel method. The magnetic study reveals that coercivity, Neel temperature and remanent magnetization strongly depend on shape of the particle. The nanoparticle with sphere-like shape exhibits magnetization curve of antiferromagnetic (AFM) ordering with ferromagnetic (FM) component. As the particle shape changes from sphere-like to cuboid, the AFM component is dominating over the ferromagnetic component. A small exchange bias is also observed at low temperature in both the sphere-like and cuboid nanoparticle. The coercivity, remanent magnetization and Neel temperature of sphere-like nanoparticle is greater than cuboid nanoparticle. Ferroelectric measurement shows the remanent polarization of cuboid is greater than sphere-like nanoparticle but the coercivity is almost same. This Bi₂Fe₄O₉nanoparticle shows a small change in polarization under magnetic field. The polarization value decreases with magnetic field increases. The magnetoelectric coupling-measured by change of remanent polarization under magnetic field are found to be greater in Bi₂Fe₄O₉sphere-like nanoparticles. These shape dependent magnetic and ferroelectric properties are coming because of shape anisotropy.

Synthetic analogues of Fe(ii)–Fe(iii) minerals containing a pentagonal ‘Cairo’ magnetic lattice

Synthesis, properties and chemical modification of low-dimensional minerals.

Unequivocal evidence of enhanced magnetodielectric coupling in Gd3+substituted multiferroic Bi2Fe4O9

We report an enhanced magnetodielectric (MD) coupling in antiferromagnetic Bi₂Fe₄O₉(BFO) lightly substituted by gadolinium (Gd³⁺).