Etude par conductivite electrique de la cinetique d'oxydation des magnetites finement divisees substituees par le zinc

The oxidation kinetics by electrical conductivity of Zn-substituted magnetites into the lacunar γ phase of same spinel structure was investigated. From the α = ?(t) curves which are identified with those obtained in microbalance it was established that the kinetics is governed by a diffusion law under variable working conditions, the chemical diffusion coefficient being only constant for high zinc substitution extents. When the temperature was raised the log $\text{σ = ?(}\text{1}\text{T}\text{)}$ curves show discontinuities attributed to the precipitation of a rhombohedral phase.