ANALYSIS OF MAGNETIC AFTER-EFFECT SPECTRA IN TITANIUM-DOPED MAGNETITE

The magnetic after-effect (MAE) spectra of titanomagnetites, Fe3-x-Del taTixO4, with constant vacancy content, Delta x 10(-4), and systematic ally varied Ti4+-substitutions, 0.01 less than or equal to x less than or equal to 0.4, are thoroughly analyzed in the temperature range 4 K < T < 460 K. These spectra are characteristically modified in the pre sence of already small Ti4+-substitutions (x greater than or equal to 0.01): (i) the order-dependent, low-temperature (T < 125 K) electronic relaxations are severely affected; (ii) the ionic, vacancy-mediated p rocess III1,2 (300 K) splits up into two satellites III (260 K) and I II1,2 (around 400 K); (iii) near 200 K, additionally process IV1,2 dev elops which is deduced to be of interstitial type. In terms of plausib le models, the mechanisms and respective interrelations of these vario us processes are clearly revealed and their activation parameters nume rically determined.