VALENCE STATES OF COPPER AND CATION DISTRIBUTION IN SUBMICRON COPPER FERRITE SPINELS 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1)

Valence states studies of copper and iron ions and their cation distri bution on both octahedral (B) and tetrahedral (A) sites on the spinel structure of submicron copper-substituted magnetites, CuxFe3-xO4 (O le ss than or equal to x less than or equal to 1) which are oxidized in c ation deficient spinels CuxFe3-O-x(4+delta) (0 less than or equal to d elta less than or equal to 0.5) have been performed by TG, DTG, FT-IR and XPS when the copper content determine the number of oxidizable cat ions 1-x = (Fe2+ + Cu+) per mole of ferrite. It was demonstrated that Fe2+ and Cu+ ions are oxidized into Fe3+ and Cu2+ ions below 300 degre es C and that the availability to diffuse could be envisaged as follow s : Cu-B(+) (130 degrees C) < Fe-B(2+) (185 degrees C < Cu-A(+)(240 de grees C). For high copper content (x greater than or equal to 0.4), th e presence of additional interstitial Cu+ ions in tetrahedral sites ha s also been found.