Diffusion Mechanism of Oxide Ions in Mn-Zn -ferrites
Oxygen self-diffusion coefficients in a manganese zinc ferrous ferrite single crystals were determined at various oxygen partial pressures by means of a secondary ion mass spectrometer. Temperature dependence of diffusivity of oxide ions consisted of three parts. The characteristics at middle temperature range above 5 hPa oxygen partial pressure exhibited a behavior as an extrinsic one and was described as;<BR>D=4.8×10<SUP>-6</SUP>⋅P<SUP>0.35</SUP><SUB>O2</SUB> exp(-137kJ/mol/RT)cm<SUP>2</SUP>⋅s<SUP>-1</SUP><BR>This activation energy corresponded to the barrier for the migration of oxide ions in spinel structure. The dependence of oxygen self-diffusion on oxygen partial pressure exhibited a positive sign (slope value: 0.35). This phenomenon suggests that the oxygen ions diffuse in Mn-Zn ferrite through interstitial sites above 5 hPa of the oxygen partial pressure.
粉体および粉末冶金 46(1), 28-35, 1999-01-15
Japan Society of Powder and Powder Metallurgy