Exsolution of oxygen impurity from diamond lattice and formation of pressurized CO2-I precipitates

Diamond single crystals showing Infra-red features of pressurized CO2-I phase were studied using Transmission Electron Microscopy (TEM) and tomography. Numerous O-containing precipitates with sizes up to 45 nm are observed. The absolute majority these decorate dislocation loops or located inside them; individual scattered also present. Morphology the varies from quasi-isometric octahedra highly flattened elongated ones. Close association implies their formation by exsolution oxygen impurity diamond lattice; size distribution suggests that equilibrium state is not yet reached. Presumably, morphology precise chemical composition depend on P-T-t evolution crystal corresponding changes in supersaturation lattice. CO2-containing diamonds often contain micron-sized hexagonal lamellar inclusions. TEM investigation a lamellae reveals it consists high quality graphite partial epitaxial relation comprising diamond. gap between may be enriched impurity.