Abstract :
The effect upon the ferrimagnetic resonance curve of different ferrite firing temperatures in the range 1250ߝ1450°C has been studied. The ferrite used had the approximate composition 0.9 MgO, 0.1 MnO, 0.8 Fe2O3, and measurements were made on polycrystalline spheres at wavelengths close to 0.866 and 1.244cm. Two parameters are used to describe the resonance curve: ΔHr is the magnetic field by which the resonance field is less than that required for a g-value of 2.000 while ΔH¿ is the separation of the two points on the resonance curve where the absorption is half maximum absorption. The experimental data show that (a) The observed g-values are close to 2.00, and ΔHr does not significantly alter on changing the measuring frequency. It decreases with increase of temperature. (b) For a given sample, ΔH¿ is substantially the same at the two frequencies but decreases with increase of temperature. (c) At a given measuring temperature, ΔH¿ decreases with firing temperature of the sample up to 1350°C but is not markedly altered by the higher firing temperatures 1400 and 1450°C. Possible contributions by magnetocrystalline anisotropy and specimen porosity to the observed effects are briefly discussed.
