Voidites in diamond Evidence for a crystalline phase containing nitrogen

Small octahedral bubbles (′voidites′), 10–100 Å in diameter, occur in some type Ia diamonds. In a study of one such specimen, electron diffraction and moiré fringe analysis have been used to demonstrate that the bubbles contain a crystalline cubic phase. Energydispersive X-ray microanalysis on the 20 Å scale provides evidence that the phase contains nitrogen. The cell constants derived from the electron diffraction data are consistent with X-ray and compressibility data for solid ammonia, although the possibility of a hitherto unreported phase of solid N2 cannot be ruled out.