Influence of different organic fuels on the phase composition, structure parameters and magnetic properties of hexaferrites BaFe12O19 synthesized by the sol-gel combustion

Phase composition, structure parameters, morphology and basic magnetic characteristics – the specific saturation magnetization values and the magnetic anisotropy fields of the nanostructured BaFe₁₂O₁₉ powders prepared by the sol-gel combustion with the following annealing at 850°С for six hours are investigated. As organic fuels the following materials are used: carbamide (CON₂H₄), sucrose (C₁₂H₂₂O₁₁), glycine (C₂H₅NO₂) and citric acid (C₆H₈O₇). The influences of the type of the organic fuels on the properties of synthesized materials are analysed. It is shown that in the powders obtained the distribution of particles on the size, the values of saturation magnetizations and the anisotropy fields depend on the fuel type. The sample synthesized using carbamide has the smallest content of the target phase BaFe₁₂O₁₉, the widest particle size distribution and the lowest value of the saturation magnetization in comparison with the other samples. The narrowest distribution of the particles on the size and the highest value of the specific saturation magnetization are observed in the material synthesized with the use of citric acid as an organic fuel. A comparison of the experimental hysteresis loops with the calculated magnetization curves is made. It is shown that the paraprocess plays a significant role in the magnetization processes of the synthesized materials (χ_para. ≈ 0.125*10⁻³ cm³/g). A technique for determining the values of the anisotropy fields and the magnetomechanical ratios from experiments on FMR is also described. Calculations of the magnetization curve and the ferromagnetic resonance line of hexaferrites powders with uniaxial anisotropy were carried out in the independent grains approach.