Synthesis of Higher Chromium Oxides Using Ozone Gas

Ozone gas in an ambient pressure was blown to Cr₂O₃ powder. The higher oxides, CrO₃, Cr₂O₅, Cr₅O₁₂, and Cr₃O₈, could be synthesized above 373 K. Both CrO₃ and Cr₂O₅ were found by in situ X-ray diffraction measurements. It was known that they could be produced only at high pressure of oxygen and at high temperatures. The CrO₃ formed was melted at 470 K in an ozone atmosphere and decomposed above 500 K. Because of thermal decomposition of ozone and the higher oxides, no higher oxides were formed above 660 K. The phase formation was discussed using the kinetic stability diagram.