Thermoluminescence studies on HPHT diamond crystals exposed to β-irradiation

2015 ◽  
Vol 212 (11) ◽  
pp. 2507-2511 ◽  
Author(s):  
M. I. Gil-Tolano ◽  
R. Meléndrez ◽  
B. Castañeda ◽  
S. Alvarez-Garcia ◽  
M. Pedroza-Montero ◽  
...  
Keyword(s):  
Diamond Crystals ◽  
Β Irradiation

Effect of pressure on synthetic diamond crystals at high temperatures and pressures in Fe/Ni catalyst system

CrystEngComm ◽  
2021 ◽  
Author(s):  
Shuai Fang ◽  
Yongkui Wang ◽  
Liangchao Chen ◽  
Zhiyun Lu ◽  
Zhenghao Cai ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Growth Mechanism ◽  
Synthetic Diamond ◽  
Natural Diamond ◽  
Catalyst System ◽  
Necessary Condition ◽  
Ni Catalyst ◽  
Effect Of Pressure ◽  
Diamond Crystals ◽  
System P

Pressure is a necessary condition for the growth of natural diamond. Studying the effect of pressure on the nitrogen content of diamond is important for exploring the growth mechanism of...

Generation of laser radiation by color centers in diamond crystals (review)

2021 ◽  
Author(s):  
V. P. Mironov ◽  
E. A. Protasova ◽  
E. I. Lipatov ◽  
E. F. Martynovich
Keyword(s):  
Laser Radiation ◽  
Color Centers ◽  
Diamond Crystals

Characterization of diamond thin films: Diamond phase identification, surface morphology, and defect structures

1989 ◽  
Vol 4 (2) ◽  
pp. 373-384 ◽  
Author(s):  
B. E. Williams ◽  
J. T. Glass
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Methane Concentration ◽  
Microwave Plasma ◽  
Defect Density ◽  
Diamond Films ◽  
Hydrogen Gas ◽  
Phase Identification ◽  
Diamond Crystals ◽  
Thin Carbon

Thin carbon films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced CVD have been examined by Auger electron spectroscopy, secondary ion mass spectrometry, electron and x-ray diffraction, electron energy loss spectroscopy, and electron microscopy. They were determined to be similar to natural diamond in terms of composition, structure, and bonding. The surface morphology of the diamond films was a function of position on the sample surface and the methane concentration in the feedgas. Well-faceted diamond crystals were observed near the center of the sample whereas a less faceted, cauliflower texture was observed near the edge of the sample, presumably due to variations in temperature across the surface of the sample. Regarding methane concentration effects, threefold {111} faceted diamond crystals were predominant on a film grown at 0.3% CH4 in H2 while fourfold {100} facets were observed on films grown in 1.0% and 2.0% CH4 in H2. Transmission electron microscopy of the diamond films has shown that the majority of diamond crystals have a very high defect density comprised of {111} twins, {111} stacking faults, and dislocations. In addition, cross-sectional TEM has revealed a 50 Å epitaxial layer of β3–SiC at the diamond-silicon interface of a film grown with 0.3% CH4 in H2 while no such layer was observed on a diamond film grown in 2.0% CH4 in H2.

Growth mechanism of icosahedral and other five-fold symmetric diamond crystals

2015 ◽  
Vol 25 (5) ◽  
pp. 1587-1598 ◽  
Author(s):  
Qiu-ping WEI ◽  
Li MA ◽  
Jun YE ◽  
Zhi-ming YU
Keyword(s):  
Growth Mechanism ◽  
Diamond Crystals

Synthesis of diamond crystals from oxygen-acetylene flames on a metal substrate at low temperature

Carbon ◽  
1998 ◽  
Vol 36 (5-6) ◽  
pp. 581-585 ◽  
Author(s):  
E.V. Grigoryev ◽  
V.N. Savenko ◽  
D.V. Sheglov ◽  
A.V. Matveev ◽  
V.A. Cherepanov ◽  
...  
Keyword(s):  
Low Temperature ◽  
Metal Substrate ◽  
Diamond Crystals

scholarly journals Experimental Etching of Diamonds: Extrapolation to Impact Diamonds from the Popigai Crater (Russia)

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1229
Author(s):  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksei Chepurov ◽  
Ivan Gryaznov ◽  
Anatoly Chepurov ◽  
...  
Keyword(s):  
Large Range ◽  
Ambient Pressure ◽  
Inert Gases ◽  
Oxidation States ◽  
Silicate Melts ◽  
Etch Pits ◽  
Diamond Crystals ◽  
Surface Graphitization ◽  
O2 Diffusion ◽  
The Impact

Diamond etching in high-temperature ambient-pressure experiments has been performed aimed to assess possible postimpact effects on diamonds in impact craters, for the case of the Popigai crater in Yakutia (Russia). The experiments with different etchants, including various combinations of silicate melts, air, and inert gases, demonstrated the diversity of microstructures on {111} diamond faces: negative or positive trigons, as well as hexagonal, round, or irregularly shaped etch pits and striation. The surface features obtained after etching experiments with kimberlitic diamonds are similar to those observed on natural impact diamonds with some difference due to the origin of the latter as a result of a martensitic transformation of graphite in target rocks. Extrapolated to natural impact diamonds, the experimental results lead to several inferences: (1) Diamond crystals experienced natural oxidation and surface graphitization during the pressure decrease after the impact event, while the molten target rocks remained at high temperatures. (2) Natural etching of diamonds in silicate melts is possible in a large range of oxidation states controlled by O2 diffusion. (3) Impact diamonds near the surface of molten target rocks oxidized at the highest rates, whereas those within the melt were shielded from the oxidizing agents and remained unchanged.

scholarly journals Intensification of diamond purification from hydrophilic minerals in foam separation process

2021 ◽  
Vol 57 (1) ◽  
pp. 19-26
Author(s):  
G.P. Dvoichenkova ◽  
V.V. Morozov ◽  
E.G. Kovalenko ◽  
Y.A. Podkamenny
Keyword(s):  
Thermal Treatment ◽  
Separation Process ◽  
Combined Method ◽  
Technological Research ◽  
Foam Separation ◽  
Diamond Crystals

The reason for diamond loss in foam separation process consists in the fact that the diamond crystals fed to the foam separation are coated with hydroxides and carbonates. A combined method to restore the diamond hydrophobicity through thermal and electrochemical destruction of the mineral coat was proposed. This method provides for the conditioning stage in the foam separation process to enable decreasing the amount of the minerals coating diamonds surface from 3 to 10 times. Technological research showed that using products of diaphragm less electrolysis of recirculating water, with the thermal treatment of the foam separation feed enables increasing the recovery of diamonds in the foam separation concentrate from 76.5% to 83.7%.

scholarly journals INFLUENCE OF COPPER SUBLAYER ON NUCLEATION OF DIAMOND CRYSTALS ON SURFACE OF TUNGSTEN CARBIDE

2018 ◽  
Vol 59 (8) ◽  
pp. 85 ◽  
Author(s):  
Dmitriy S. Vokhmyanin
Keyword(s):  
Raman Spectroscopy ◽  
Phase Composition ◽  
Tungsten Carbide ◽  
Layer Structure ◽  
Chemical Deposition ◽  
Diamond Crystals ◽  
Negative Temperatures

The buffer copper sublayer on the surface of tungsten carbide was obtained with the chemical deposition from aqeous solutions. With the using the methods of SEM, AFM, XRF it was established that at temperature of 23 °C the layer structure is porous that do not observed at negative temperatures. The sublayer structure influences the character of nucleation of diamond crystals and their form. The phase composition was determined with Raman spectroscopy. The spectrum shows the lines of diamond (1334 cm-1), sp2 of carbon and trans-polyacetylene (1170 сm-1). 

scholarly journals Precambrian diamond crystals from the Siberian craton

2019 ◽  
Vol 489 (6) ◽  
pp. 611-615
Author(s):  
V. P. Afanasiev ◽  
N. P. Pokhilenko ◽  
E. O. Egorova ◽  
E. S. Leendenblot
Keyword(s):  
Siberian Craton ◽  
Diamond Crystals ◽  
History Of

Analysis of diamond grains from placers in the northeastern Siberian craton shows that some diamond varieties (round dodecahedra, varieties II and V-VII in the classification of Orlov) may originate from Precambrian sources. The Precambrian diamonds have different sedimentation histories. Namely, diamonds of varieties V-VII are most strongly rounded though being the most resistant to wear. Therefore, they should have the longest history of dispersal and transport, and thus should be derived from the oldest primary deposits.

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