A study of the magnetic after-effect in W-hexagonal compounds

The relaxation of the initial permeability is measured in barium ferrite samples with W-hexagonal structure. In the temperature range between 80 and 420 K three clear relaxation processes are found; these features are influenced by sintering temperature and atmosphere. Peak C (370 K) seems to arise from long range cation diffusion processes via vacancies, with activation energies around 1.1 eV. Peak B (300 K) can be attributed to local rearrangements of ferrous cations in octahedral position via lattice vacancies and can be fitted by the superposition of two Debye processes with activation energies close to 0.80 and 0.84 eV. Peak A exhibits the characteristics of a single Debye process with an activation energy on the order of 0.48 eV and its origin is not yet clear.<>