La and Co substituted M-type barium ferrites processed by sol-gel combustion synthesis

The flake-like Ba_1-xLa_xCo_xFe _12-xO₁₉ (x = 0.0-0.4) were synthesized using sol-gel combustion synthesis process followed by the thermal insulation process and heating treatment. The synthesis process was investigated and the structure details, morphology, and magnetic properties were evaluated. TG/DTA was used to investigate the formation mechanism and to identify the thermal insulation temperature at 400 C followed by the heat treatment temperature at 1200 C. XRD patterns demonstrated that the unit cell volume and particle size decreased with the increase of the substitution content. The typical particles size was in the range of 1-2 μm in the planar dimension whilst the thickness was in the range of 200-500 nm. It was found from the VSM graphs that the saturation magnetizations M_s reached a maximum of 68.15 emu g^-1 at x = 0.3 and then decreases to 64.72 emu g^-1 at x = 0.3 whilst the coercivity H_c sustained decreases from 2190.70 to 1181.07 Oe g ^-1 with substitution content increased from 0 to 0.4.