Solution combustion route for Ni and Al co-doped lithium ferrite nanoparticles: Synthesis, the effect of doping on the structural, morphological, optical, and magnetic properties

Abstract

Nickel and Aluminum co-doped Lithium Ferrite Nano-particles, (Li1-xNi0.5xAlxFe1-xO2), (0 ≤ x ≤ 0.3) are synthesized through the solution combustion route with the fuel urea as a reducing agent. The prepared Nano-particles at different doping concentrations are investigated using several tools. The thermal analysis thermographs revealed a combustion reaction at around 300 °C. Doping lithium ferrite with different concentrations changes the structural, morphological, optical, and magnetic characteristics significantly. The increase of the lattice constant to 5.8 Å, and the decrement of the crystallite sizes can be related to the differences in the ionic radius of the incorporated elements, and the increment of Al content. Additional induced sub-band gap energy levels as a result of the numerous surface and interface defects in the nanoparticle structure result in a modest narrowing of the band gap (direct and indirect). The associate shift of the band gap with the decrement of the crystallite size can be attributed to the quantum confinement effect as a result in the tiny size regime. The reduction of the sample's disorder structure and the creation of pure phases were both credited with increasing the saturation magnetization of the undoped sample, but the saturation magnetization decreased when magnetic Fe3+ ions are replaced by nonmagnetic Al3+ ions. The optically active and soft ferrite nanoparticles were confirmed by the behaviour of the physical parameters before them. The synthesized nanoparticles are considered as promising materials for nonlinear optics and memory recording applications.