Texture and Genesis of Polycrystalline Varieties of Diamond Based on Phase-Contrast and Diffraction Contrast Tomography

A. Shiryaev (1) , F. V Kaminsky , Wolfgang Ludwig (2) , D. A Zolotov , A. Buzmakov (3) , S. V Titkov

1 IRI
2 ESRF - European Synchrotron Radiation Facility
3 RAS - Russian Academy of Sciences [Moscow]

Structural peculiarities of several types of cryptocrystalline diamond varieties: carbonado, impact-related yakutite and cryptocrystalline diamond aggregates from kimberlite were studied using Infrared spec-troscopy, X-ray diffraction contrast (DCT-Diffraction Contrast Tomography) and phase contrast tomogra-phy (PCT). It is shown that the porosity of the carbonado and kimberlitic cryptocrystalline aggregates is similar being in range of 5-10 vol %, possibly indicating similar formation mechanism(s), whereas that of yaku-tite is essentially zero. Crystallographic texture is observed for some carbonado samples. It is suggested that at least partially the texture is explained by deformation-related bands. Infrared spectroscopy reveals presence of hydrous and, probably, of hydrocarbon species in carbonado.

Mots clés: Diffraction-contrast tomography; texture; cryptocrystalline diamond; yakutite; Diffrac- tion-contrast tomography; phase-contrast tomography; carbonado

Domaines: Sciences de la Terre; Géochimie

A. Shiryaev, F. V Kaminsky, Wolfgang Ludwig, D. A Zolotov, A. Buzmakov, et al.. Texture and Genesis of Polycrystalline Varieties of Diamond Based on Phase-Contrast and Diffraction Contrast Tomography. Geochemistry International / Geokhimiya, 2019, 57 (9), pp.1015-1023. ⟨10.1134/S0016702919090106⟩. ⟨hal-02404548⟩