A novel stable solid formed by C₆₀ + oxygen at high P(O₂)

Abstract

We report the formation of a novel solid form of carbon + oxygen. Exposure of C₆₀ to high oxygen pressure [P(O₂) ≍ 100 MPa] for several days at slightly above ambient temperature results in absorption of significant amounts of oxygen (up to ∼48% by weight after 3 days). X-ray diffraction measurements showed that the C₆₀ pellets had become amorphous. Although part of the added weight is slowly lost in flowing oxygen at ambient pressure and temperature, most remains up to at least 100 °C. Heating in flowing He at 200 °C brought the weight back to near the original value. The reaction appears to be specific to C₆₀ since the amorphous outgassed material had lost the capacity to absorb oxygen at high P(O₂), and the oxygen absorption effect was absent in powdered graphite and in commercial amorphous carbon. The Raman spectrum differs from those of C₆₀, soot, amorphous carbon, graphite, and diamond.