Enhancement of ferromagnetic and dielectric properties in lanthanum doped BiFeO3 by hydrothermal synthesis
Multiferroic Bi1−xLaxFeO3 (x = 0.0, 0.1, 0.2, and 0.3) micro-particles were successfully synthesized by a hydrothermal technique. All the samples were phase pure crystallizing in a perovskite structure with a space group of R3c. XRD refinement revealed that the lattice parameters increased along with increase of La content, while the Fe–O octahedra became more distorted. It was found that the morphologies of as-obtained micron-sized particles turned from spheroidal to octahedral according to different doping levels. The dielectric constant of Bi1−xLaxFeO3 sample increased after La doping, and reached the largest value for the sample of x = 0.2, both in low and high frequency range at room temperature. All the as-prepared samples exhibited magnetic moments starting above room temperature. It was found that the magnetic moment was significantly enhanced from 0.264 emu/g of BiFeO3 to 0.658 emu/g of Bi0.9La0.1FeO3 in a field of 3 T at 77 K. Both enhancements of ferromagnetic and dielectric properties possibly attribute to the changes of lattice parameters and Fe–O bond lengths caused by lanthanum substitution.