scholarly journals Mechanistic insights of seeded diamond growth from molecular precursors

2021 ◽  
pp. 108796
Author(s):  
Christopher P. Ender ◽  
Jiaxu Liang ◽  
Jonas Friebel ◽  
Todd Zapata ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Diamond Growth ◽  
Molecular Precursors

scholarly journals Diamond growth from organic compounds in hydrous fluids deep within the Earth

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Maria Luce Frezzotti
Keyword(s):  
Organic Compounds ◽  
Subduction Zones ◽  
Diamond Growth ◽  
Diamond Surfaces ◽  
Molecular Precursors ◽  
Carbon Saturation ◽  
Carboxylate Groups ◽  
Dissolved Species ◽  
Lithospheric Plates ◽  
The Alps

Abstract At subduction zones, most diamonds form by carbon saturation in hydrous fluids released from lithospheric plates on equilibration with mantle rocks. Although organic molecules are predicted among dissolved species which are the source for carbon in diamonds, their occurrence is not demonstrated in nature, and the physical model for crustal diamond formation is debated. Here, using Raman microspectroscopy, I determine the structure of carbon-based phases inside fluid inclusions in diamond-bearing rocks from the Alps. The results provide direct evidence that diamond surfaces are coated by sp2-, and sp3-bonded amorphous carbon and functional groups of carboxylic acids (e.g., carboxyl, carboxylate, methyl, and methylene), indicating the geosynthesis of organic compounds in deep hydrous fluids. Moreover, this study suggests diamond nucleation via metastable molecular precursors. As a possible scenario, with carbon saturation by reduction of carboxylate groups, I consider tetrahedral H-terminated C groups as templates for the growth of sp3-structured carbon.

scholarly journals Mechanistic Insights of Seeded Diamond Growth from Molecular Precursors

2021 ◽  
Author(s):  
Christopher P. Ender ◽  
Jiaxu Liang ◽  
Jonas Friebel ◽  
Todd Zapata ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Diamond Growth ◽  
Molecular Precursors

scholarly journals Mechanistic Insights of Seeded Diamond Growth from Molecular Precursors

2021 ◽  
Author(s):  
Christopher P. Ender ◽  
Jiaxu Liang ◽  
Jonas Friebel ◽  
Todd Zapata ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Diamond Growth ◽  
Molecular Precursors

The value of Electron Microscope studies of imperfect natural diamonds

1990 ◽  
Vol 48 (4) ◽  
pp. 194-195
Author(s):  
J C Walmsley ◽  
A R Lang
Keyword(s):  
Electron Microscope ◽  
Classification Scheme ◽  
Natural Diamond ◽  
Sudden Change ◽  
Growth Conditions ◽  
Diamond Growth ◽  
Major Constituent ◽  
Natural Diamonds ◽  
Type Ia ◽  
Platelet Defects

Interest in the defects and impurities in natural diamond, which are found in even the most perfect stone, is driven by the fact that diamond growth occurs at a depth of over 120Km. They display characteristics associated with their origin and their journey through the mantle to the surface of the Earth. An optical classification scheme for diamond exists based largely on the presence and segregation of nitrogen. For example type Ia, which includes 98% of all natural diamonds, contain nitrogen aggregated into small non-paramagnetic clusters and usually contain sub-micrometre platelet defects on {100} planes. Numerous transmission electron microscope (TEM) studies of these platelets and associated features have been made e.g. . Some diamonds, however, contain imperfections and impurities that place them outside this main classification scheme. Two such types are described.First, coated-diamonds which possess gem quality cores enclosed by a rind that is rich in submicrometre sized mineral inclusions. The transition from core to coat is quite sharp indicating a sudden change in growth conditions, Figure 1. As part of a TEM study of the inclusions apatite has been identified as a major constituent of the impurity present in many inclusion cavities, Figure 2.

Role of the plasma composition at the surface on diamond growth

1998 ◽  
Vol 08 (PR7) ◽  
pp. Pr7-391-Pr7-399 ◽  
Author(s):  
S. Farhat ◽  
C. Findeling ◽  
F. Silva ◽  
K. Hassouni ◽  
A. Gicquel
Keyword(s):  
Diamond Growth ◽  
Plasma Composition

Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes

2020 ◽  
Author(s):  
Boris Sheludko ◽  
Cristina Castro ◽  
Chaitanya Khalap ◽  
Thomas Emge ◽  
Alan Goldman ◽  
...  
Keyword(s):  
Gas Phase ◽  
Active Site ◽  
Lower Cost ◽  
Open Systems ◽  
Iridium Complexes ◽  
Terminal Olefin ◽  
Molecular Precursors ◽  
Sterically Demanding ◽  
Olefin Production ◽  
Steam Cracking

<b>Abstract:</b> The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO-<sup>R4</sup>POCOP)Ir(CO)] (<sup>R4</sup>POCOP = κ<sup>3</sup>-C<sub>6</sub>H<sub>3</sub>-2,6-(OPR<sub>2</sub>)<sub>2</sub>) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes <a>[(≡SiO-<i><sup>t</sup></i><sup>Bu4</sup>POCOP)Ir(CO)] </a>(<b>1</b>) and [(≡SiO-<i><sup>i</sup></i><sup>Pr4</sup>PCP)Ir(CO)] (<b>2</b>) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77%. The results indicate that the active site is conserved upon immobilization.

DIAMOND GROWTH IN ALKALI BRINES

2017 ◽  
Author(s):  
Rebecca Stone ◽  
◽  
Melissa Strawson ◽  
Robert Luth
Keyword(s):  
Diamond Growth

scholarly journals Deposition of Boron-Doped Thin CVD Diamond Films from Methane-Triethyl Borate-Hydrogen Gas Mixture

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 666 ◽  
Author(s):  
Nikolay Ivanovich Polushin ◽  
Alexander Ivanovich Laptev ◽  
Boris Vladimirovich Spitsyn ◽  
Alexander Evgenievich Alexenko ◽  
Alexander Mihailovich Polyansky ◽  
...  
Keyword(s):  
Film Growth ◽  
Chemical Vapor ◽  
Hydrogen Gas ◽  
Diamond Growth ◽  
Structural Defects ◽  
Boron Doped Diamond ◽  
Diamond Deposition ◽  
Synthesis Conditions ◽  
Surface Etching ◽  
Boron Doped

Boron-doped diamond is a promising semiconductor material that can be used as a sensor and in power electronics. Currently, researchers have obtained thin boron-doped diamond layers due to low film growth rates (2–10 μm/h), with polycrystalline diamond growth on the front and edge planes of thicker crystals, inhomogeneous properties in the growing crystal’s volume, and the presence of different structural defects. One way to reduce structural imperfection is the specification of optimal synthesis conditions, as well as surface etching, to remove diamond polycrystals. Etching can be carried out using various gas compositions, but this operation is conducted with the interruption of the diamond deposition process; therefore, inhomogeneity in the diamond structure appears. The solution to this problem is etching in the process of diamond deposition. To realize this in the present work, we used triethyl borate as a boron-containing substance in the process of boron-doped diamond chemical vapor deposition. Due to the oxygen atoms in the triethyl borate molecule, it became possible to carry out an experiment on simultaneous boron-doped diamond deposition and growing surface etching without the requirement of process interruption for other operations. As a result of the experiments, we obtain highly boron-doped monocrystalline diamond layers with a thickness of about 8 μm and a boron content of 2.9%. Defects in the form of diamond polycrystals were not detected on the surface and around the periphery of the plate.

Sign in / Sign up

Export Citation Format

Share Document