PHASE-STABILITY AND IONIC TRANSFERENCE NUMBER OF A FERRITE SPINEL, MN0.54ZN0.35FE2.11O4

We have determined in situ the phase stability region of a Mn-Zn ferri te spinel Mn0.54Zn0.35Fe2.11O4 from the isothermal variation of total conductivity with oxygen partial pressure (P-O2) at elevated temperatu res and its mean cationic transference number via a modified Tubandt-l ike electrotransport experiment in its entire stability range. At a gi ven temperature, the ionic transference number increases with increasi ng P-O2 in oxidizing atmospheres and with decreasing P-O2 in reducing atmospheres, leaving a minimum in between. By combining the total cond uctivity and the transference number, the partial ionic conductivity h as been extracted and analyzed in the light of defect structure and mo bility of the ferrite spinel. It has also been observed that an electr otransport-induced unmixing occurs especially at interstitial-dominati ng reducing atmospheres.