Cobalt Impurity, Cation Vacancies and the Magnetic Relaxation of Magnetite

Disaccommodation spectrum of magnetite found by Braginski were investigated experimentally and theoretically. Peak II is caused by the presense of extremely small concentration of cobalt impurity and it disappears for the high purity magnetite. Peak III is caused by the preferential occupation of cation vacancies and the accurate expression of the relaxation time is 1/τ=8 I 0 =6.0×10 13 exp (- Q / k T ), where Q =0.94 eV and I 0 is the jumping frequency of an iron ion into the nearest neighbor cation vacancy. A suggestion is made for the low temperature line width anomaly of Li 0.5 Fe 2.5 O 4 that it is due to ppm cobalt impurity.