Structural and magnetic behaviour of aluminium doped barium hexaferrite nanoparticles synthesized by solution combustion technique

Nanocrystalline M-type Al3+ substituted barium hexaferrite samples having generic formula BaFe12−xAlxO19 (where x=0.00, 0.25, 0.50, 0.75, 1.00) were synthesized by the solution combustion technique. The precursors were prepared using stoichiometric amounts of Ba2+, Fe3+ and Al3+ nitrate solutions with citric acid as a chelating agent. The barium nitrate to citric acid ratio was taken as 1:2 and pH of the solution was kept at 8. The sintered samples were characterized by XRD, EDAX, SEM, TEM and VSM techniques. Pure barium hexaferrite shows only single phase hexagonal structure while samples at 0.25≤x≥1.00 show α-Fe2O3 peaks with M-phase of barium hexaferrite in the X-ray diffraction pattern. The lattice parameters (a and c) obtained from XRD data decreases with increase in aluminium content x. The particle size obtained from X-ray diffraction data is in the nanometer range. The magnetic behaviour of the samples was studied using vibrating sample magnetometer technique. The saturation magnetization (Ms) and magneton number (nB) decrease from 38.567 to 21.732 emu/g and from 7.6752 to 4.2126μB, respectively, with increase in Al3+ substitution x from x=0.0 to 1.0.

Research highlights
► Preparation of barium hexaferrite by solution combustion.
► Characterization techniques used are XRD, VSM, TEM, EDAX and SEM.
► Substitution of Al3+ ions.
► Structural properties.
► Magnetic properties.