Chromium dioxide (CrO2) powders have been synthesised by decomposing CrO3 and Cr2O5 powders under hydrothermal conditions in the temperature range of 300–500°C and pressure range of 250–1200 bars. Oxides of antimony and iron have been used as modifiers to induce acicular morphology. A novel method of using alkali metal salts such as chlorides and carbonates as mineralisers produces CrO2 with superior magnetic characteristics. The particle size distributions have been correlated with the magnetic properties of the materials. The products obtained have properties rendering them useful for magnetic recording applications.
Hydrothermal synthesischromium dioxidemagnetic recording materialparticle size distribution