A NOVEL STABLE SOLID FORMED BY C-60 PLUS OXYGEN AT HIGH P(O2)

We report the formation of a novel solid form of carbon + oxygen. Expo sure of C60 to high oxygen pressure [P(O2) almost-equal-to 100 MPa] fo r several days at slightly above ambient temperature results in absorp tion of significant amounts of oxygen (up to approximately 48% by weig ht after 3 days). X-ray diffraction measurements showed that the C60 p ellets had become amorphous. Although part of the added weight is slow ly lost in flowing oxygen at ambient pressure and temperature, most re mains up to at least 100-degrees-C. Heating in flowing He at 200-degre es-C brought the weight back to near the original value. The reaction appears to be specific to C60 since the amorphous outgassed material h ad lost the capacity to absorb oxygen at high P(O2), and the oxygen ab sorption effect was absent in powdered graphite and in commercial amor phous carbon. The Raman spectrum differs from those of C60, soot, amor phous carbon, graphite, and diamond.