The change of Fe–Ni alloy inclusions in synthetic diamond crystals due to annealing

Чепуров, А. А.; Dereppe, Jean-Marie; Fedorov, I. I.; Chepurov, A. I.

doi:10.1016/s0925-9635(00)00260-0

Cited by 23 publications

(10 citation statements)

References 8 publications

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“…During this time, inclusions of silicates, oxides, and sulfides remained completely inert "prisoners" of diamond, which is confirmed by the experimental data (Fedorov et al, 2006). On the other hand, inclusions of metals at mantle P -T conditions are able to move through the volume of a diamond crystal by recrystallization of the diamond substance, thereby reaching the surface of the crystal and leaving the diamond (Chepurov et al, 2000;Fedorov et al, 2005). Thus, this process of self-purification of diamond from inclusions of metal melts can serve as one of the explanations for the relatively rare findings of native iron inclusions in natural diamonds.…”

Section: Application To Natural Geological Environmentssupporting

confidence: 58%

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How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology

Сонин

Dereppe²,

Жимулев

et al. 2020

Eur. J. Mineral.

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Abstract. The origin and evolution of metal melts in the Earth's mantle and their role in the formation of diamond are the subject of active discussion. It is widely accepted that portions of metal melts in the form of pockets can be a suitable medium for diamond growth. This raises questions about the role of silicate minerals that form the walls of these pockets and are present in the volume of the metal melt during the growth of diamonds. The aim of the present work was to study the crystallization of diamond in a complex heterogeneous system: metal-melt–basalt–carbon. The experiments were performed using a multianvil high-pressure apparatus of split-sphere type (BARS) at a pressure of 5.5 GPa and a temperature of 1500 ∘C. The results demonstrated crystallization of diamond in metal melt together with garnet and clinopyroxene, whose chemical compositions are similar to those of eclogitic inclusions in natural diamond. We show that the presence of silicates in the crystallization medium does not reduce the chemical ability of metal melts to catalyze the conversion of graphite into diamond, and, morphologically, diamond crystallizes mainly in the form of a cuboctahedron. When the content of the silicate material in the system exceeds 5 wt %, diamond forms parallel-growth aggregates, but 15 wt % of silicate phases block the crystallization chamber, preventing the penetration of metallic melt into them, thus interrupting the growth of diamond. We infer that the studied mechanism of diamond crystallization can occur at lower-mantle conditions but could also have taken place in the ancient continental mantle of the Earth, under reducing conditions that allowed the stability of Fe–Ni melts.

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Section: Application To Natural Geological Environmentssupporting

confidence: 58%

“…The measurement error is +0.2 GPa and +25 • C. Heating of the samples was performed after pressurization, and after the experiment the samples were cooled by quenching. Further experimental details with photographs are available in Chepurov et al (2010), Zhimulev et al (2012), and Tomilenko et al (2015).…”

Section: Experimental Methodsmentioning

confidence: 99%

How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology

Сонин

Dereppe²,

Жимулев

et al. 2020

Eur. J. Mineral.

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“…And, finally, it is difficult to explain with the "inclusion" model the appearance of SAXS by the annealing of natural diamond. Whereas there are some indications that upon annealing, microscopic metal inclusions can migrate and coalesce (Chepurov et al, 2000), such migration was never observed or proposed for silicate/sulphide inclusions, common for natural diamonds.…”

Section: Discussionmentioning

confidence: 94%

Small-angle X-ray scattering of extended defects in diamonds

Shiryaev¹,

Klyuev²,

Naletov³

et al. 2003

J Appl Cryst

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Results of the small-angle X-ray scattering (SAXS) of diamonds with different concentrations and types of optically-active defects are reviewed. It is shown that nitrogen-free (IIA) diamonds and diamonds with a low degree of nitrogen aggregation have no SAXS. Annealing of diamonds leads to the formation of three-dimensional clusters of defects with sizes in the range from ~8 to 60 nm. There is no correlation between nitrogen concentration and the existence or the size of the clusters, however, the clusters are related to the degree of diamond annealing. The presence of the clusters is unrelated to 'platelets' and they contain little, if any, nitrogen. With annealing, the size of the clusters decreases and the contrast of electronic density with the matrix increases.

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“…Type IIa natural brown diamond was transformed from brown to colorless via HPHT annealing . These HPHT annealing experiments often occurred at a higher pressure ranging between 5 and 9 GPa. ,− High pressure, meaning high equipment costs, should be reduced to improve scientific research and commercial treatment. , The material properties of the pressure medium (pyrophyllite, dolomite, and graphite) was constrained, where the low pressure and the high temperature annealing experiments at a high-pressure experimental apparatus are precarious and it is difficult to control the annealing condition stability. We performed experiments on diamond annealing under a relatively safe and stable pressure of 2.5 GPa.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Various Centers in Synthetic Type Ib Diamond under HPHT Annealing

Chen

et al. 2018

Crystal Growth & Design

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In this study, type Ib diamond annealing experiments were successfully performed under a pressure of 2.5 GPa and a high temperature range between 1680 and 2060 °C. The color of the diamond changed from yellow to light yellow, and the nitrogen (N) state changed from the isolate C-center to the aggregated A-center as the annealing temperature increased. The NV0 center was detected when the annealing temperature was under 1840 °C, and not detected when the temperature reached 1920 °C. The NV– center was more stable than the NV0 center at an annealing temperature of 1920 °C. When the annealing temperature reached 1990 °C, the NE8 center appeared in the diamond lattice. When the annealing pressure changed from 2.5 to 5 GPa, high pressure would restrict the formation of A-center N but hardly affected the formation of NV− center in the diamond lattice. This was the first known report on the successful preparation of the type IaA diamond under a lower pressure of 2.5 GPa. Our experiment results could be helpful for further understanding the formation of various centers in the diamond lattice and provided data for distinguishing the annealed synthesized diamond from the natural diamond in the jewelry market.

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The change of Fe–Ni alloy inclusions in synthetic diamond crystals due to annealing

Cited by 23 publications

References 8 publications

How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology

How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology

Small-angle X-ray scattering of extended defects in diamonds

Characterization of Various Centers in Synthetic Type Ib Diamond under HPHT Annealing

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