A STUDY OF THE MAGNETIC AFTER-EFFECT IN W-HEXAGONAL COMPOUNDS

The relaxation of the initial permeability is measured in barium ferri te samples with W-hexagonal structure. In the temperature range betwee n 80 and 420 K three clear relaxation processes are found which featur es are influenced by sintering temperature and atmosphere. Peak C (370 K) seems to arise from long range cation diffusion processes via vaca ncies, with activation energies around 1.1 eV, Peak B (300 K) can be a ttributed to local rearrangements of ferrous cations in octahedral pos ition 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 a ctivation energy of the order of 0.48 eV and its origin is not yet cle ar.