Dependence of static strength of large single crystals of synthetic diamond type and Ib octahedral habit after heat treatment on their size

This article focuses on the problem of using large single crystals of type Ib synthetic diamond in single crystal and drilling tools. According to the literature review for the use of large diamonds in drilling equipment relevant conditions. The is shown possible negative effects of the temperature load on the diamond single crystal. The is presented developed technique for estimating the static strength of large diamond single crystals. It has been shown that microcrystals in the form of octahedra and cubes are formed as a result of heat treatment on the surface of synthetic diamond single crystals. The results of studies of the strength of large single crystals of synthetic diamonds of millimeter size are shown. In contrast to the classical approach, when IIb crystals are used for the production of drilling equipment, we present Ib crystals because they are closer to natural diamond in terms of physical and mechanical properties. The static strength criterion was used to assess the strength. It has been shown that crystals with a size of 1000 ... 1100 μm have a higher value of static strength than crystals with a size of 1200 μm and larger.

ANALYSIS OF PRECIOUS GEMSTONES IN THE COLLECTION OF THE EARTH SCIENCE MUSEUM, BY OPTICAL AND SCANNINGELECTRON MICROSCOPY. THE FIRST RESULTS

For the first time, a study of the chemical composition and diagnostic properties of gemstones of the main collection of the Earth Science Museum at Moscow State University has been carried out. The modern non-destructive analytical methods were used. These were the optical and scanning electron microscopy, which make it possible to study material composition without special sampling or probing, the latter fact being highly relevant in the museum field. Optical microscopy data showed that the majority of the studied gems contain a lot of fluid and solid inclusions of other minerals, indicating the natural origin of the examined samples. Typomorphic features of emerald crystals show a shale genetic type of this species. Data from scanning electron microscopy revealed the presence of boron impurity in the composition of diamond single crystals.

Growth and characterization of diamond single crystals grown in the Fe–S–C system by the temperature gradient method

Diagram of the apparatus for the HPHT diamond synthesis: (a) alloy hammer + pyrophyllite assembly block; (b) sample assembly.

Towards high-quality nitrogen-doped diamond single crystals for X-ray optics

In this manuscript, characterization of single-crystalline (111) plates prepared from type-Ib diamonds with a nitrogen content of 100–150 ppm by means of high-resolution rocking-curve imaging (RCI) is reported. Contrary to common opinion regarding the intrinsically poor diffraction quality of type-I diamonds, RCI showed the presence of nearly defect-free areas of several millimetres squared in the central part of the diamond plates. The observed broadening of the rocking curves is a result of the cutting and polishing processes, causing strains around the edges of the plates and rare defects. An improvement of the preparation technique will thus allow single-crystalline diamond plates to be made for Laue and Bragg monochromators and beam splitters from type-Ib material with areas large enough to be used as optical elements at fourth-generation synchrotron facilities.