Investigation of crystal structure, dielectric and magnetic properties in La and Nd co-doped BiFeO3 multiferroics

For the investigation of the crystal structure, dielectric properties and magnetic properties of La and Nd codoped BiFeO3 multiferroics; Bi0.8La0.2-xNdxFeO3 (x=0.075, 0.1, 0.125) samples were prepared through solid state reaction method. Rietveld refinement of the obtained XRD patterns shows that there is change in crystal structure in these samples. At higher concentration of La (at x= 0.075), the crystal structure was found to have mixed symmetry with rhombohedral and triclinic phases, while with equal concentration of both the dopants (at x= 0.1), the structure changes to mixed symmetry having rhombohedral and orthorhombic phases. At higher concentration of Nd (at x= 0.125), again mixed symmetry was established having both phases of the previous composition but approximately in reverse fraction. In dielectric analysis, x= 0.1 sample showed the highest values of dielectric constant (epsilon') and dielectric loss (tan delta). For x= 0.125 sample, it was observed that the dielectric constant and dielectric loss response are improved. The magnetic characterization (M-H loops) indicates the significant enhancement in magnetisation with increasing concentration of Nd. Nd doping leads to the destruction of spiral modulation, forming the antiferromagnets, and visualisation of improved magnetisation via canting of spins.