Anelasticity in an Mn-Ferrite Single Crystal

Abstract

Anelastic behavior in a single crystal of Mn ferrite (Mn 0.82 Fe 2.18 O 4 ) was studied at temperatures between 280 and 730 K by longitudinal vibrations of 125 kHz. The acoustic loss curve showed three kinds of internal friction peaks. One of them appeared very near to the Curie temperature and was very sensitive to applied magnetic field and strain amplitudes of vibrations. This peak was explained by magneto-mechanical coupling factor and the loss tangent of magnetic permeability. Another peak was observed at 500 K by longitudinal vibrations along the [110] and [111] directions but not along [100]. This was independent of strain amplitudes of vibrations and external magnetic field. The activation energy of this peak was estimated as 0.78 eV and explained by mutual exchange between cations and their vacancies on the octahedral sites in the spinel lattice. The last one was at 300 K and independent of strain amplitudes of the vibrations and magnetic field. This peak was much smaller than the above two peaks.