Swift heavy ion irradiation of diamond powder

Sub-micrometer sized diamond powder was irradiated with 1.4 GeV uranium ions at fluences of 5 × 1012, 1 × 1013 and 8 × 1013 ions/cm2. The resulting structure of the irradiated diamond powder was investigated by synchrotron X-ray diffraction (XRD), Raman scattering and transmission electron microscopy. The high-resolution XRD measurements show that the diamond unit cell parameter increases with irradiation, and the unit cell volume increases by about 1.3‰ for the highest fluence. However, no peak broadening was observed and an ion-induced sharpening was evident after irradiation. Raman, TEM and EELS analysis confirmed that the diamond undergoes a radiation-induced transformation to a graphite-like carbon.