MAGNETIC-PROPERTIES OF COXFE3-XO4 DURING CONVERSION FROM NORMAL TO INVERSE SPINEL PARTICLES

Cobalt ferrite, CoxFe3-xO4 with 0.55<x<0.8, is produced by precipitation from aqueous solutions. Drying and annealing at temperatures below 300-degrees-C results in a coercivity that increases with increasing temperature. Mossbauer effect spectroscopy and magnetic measurements are consistent with the interpretation that these Co ferrites have a (mostly) normal spinel structure as made. These convert to a (mostly) inverse spinel structure on thermal aging. No significant morphological changes occur during this transformation. Coercivities as high as mu0H(c)=0.2 T are observed.