Studies on lanthanum-doped nickel ferrites for improved structural, magnetic and optical properties

Lanthanum-doped Nickel ferrites, Ni Lax Fe2-x O4 (x = 0.00 to 0.05 in steps of 0.01) were prepared using Citrate gel auto combustion method. The XRD patterns confirm the formation of well-defined single phase cubic spinel structure without any evidence of secondary peaks crystallite size is found to decrease from 37 to 26 nm with the addition of La3+ ions. SEM images reveal the formation of homogeneous, spherical, nanoparticles. A rise in Ms from 9 emu/g to 124 emu/g is witnessed with increase in x from VSM studies. Relatively larger values of Ms of 124 emu/g is found for x = 0.4. Non-linear variation of Ms is corroborated to the nature of dopant atom, Y-K angles and Crystallite size. Coercivity is found to vary from 256 to 291Oe with the addition of dopant atom. on the enhanced magnetic parameters of the present ferrite samples, it can be proposed that the synthesized Ni-La Ferrite (x = 0.4) sample can be applied in magnetic field applications such as permanent magnets and permanent data storage tapes and also for biomedical applications. The UV absorption range is observed to be in the visible region varying from 534 to 546 nm and the energy bandgap values are found to decrease from 2.06 eV to 1.76 eV. Observed absorption range in the visible region coupled with relatively lower values of Eg make these materials usable for optical applications.