Valence States of Copper and Cation Distribution in Submicron Copper Ferrite Spinels CuxFe3-xO4(0≤x≤1)

Overview & Synopsis

Valence States studies of copper and iron ions and their cation distribution on both octahedral (B) and tetrahedral (A) sites on the spinel structure of submicron copper-substituted magnetites, CuxFe3-xO4 (0≤x≤1) which are oxidized in cation deficient spinels CuxFe3-xO4+δ (0≤δ≤0.5) have been performed by TG, DTG, FT-IR and XPS when the copper content determine the number of oxidizable cations 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°C and that the availability to diffuse could be envisaged as follows : Cu+B(130°C) < Fe2+B(185°C) < Cu+A(240°C) . For high copper content (≥0.4), the presence of additional interstitial Cu+ ions in tetrahedral sites has also been found.