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

Abstract

Nanocrystalline M-type Al 3+ substituted barium hexaferrite samples having generic formula BaFe 12− x Al x O 19 (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 Ba 2+, Fe 3+ and Al 3+ 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-Fe 2O 3 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 ( M s) and magneton number ( n B) decrease from 38.567 to 21.732 emu/g and from 7.6752 to 4.2126μ B, respectively, with increase in Al 3+ substitution x from x=0.0 to 1.0.