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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Diamond - Types
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Keyword Index
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
Each article reference in the SDLRC is tagged with one or more key words assigned by Pat Sheahan to highlight the main topics of the article. In an effort to make it easier for users to track down articles related to a specific topic, KRO has extracted these key words and developed a list of major key words presented in this Key Word Index to which individual key words used in the article reference have been assigned. In most of the individual Key Word Reports the references are in crhonological order, though in some such as Deposits the order is first by key word and then chronological. Only articles classified as "technical" (mainly scientific journal articles) and "media" (independent media articles) are included in the Key Word Index. References that were added in the most recent monthly update are highlighted in yellow.
Diamond - Types is a variation of Diamond - Color which classifies diamonds according to the type of impurities rather than color. Type IIa diamonds which lack nitrogen as an impurity have become very topical because of their tendency to grow into very large sizes such as the Cullinan diamond and more recently Lucara's Lesedi La Rona diamond from the Karowe pipe in Botswana.
C-isotopic and N-isotopic composition and the infrared absorption spectraof coated diamonds-evidence regional uniformity of CO2-H2) rich fluids lithospheric mantle
Earth and Planetary Science Letters, Vol. 108, No. 1-3, January pp. 139-150
The 'type' classification system of diamonds and its importance in gemology. A guide to determining diamond type, and its implications for identifying treated and
Gems & Gemology, Vol. 45, 2, Summer, pp. 96-111.
Technology
Diamond classification Type 1 and type 11; synthetics
Geochemistry International, Vol. 49, 6, pp. 555-567.
Technology
Nanodiamonds
Abstract: Anomalous Xe enriched in both heavy and light isotopes (Xe-HL) was identified in the high-temperature Xe fraction in relict nanodiamond grains from chondrites, whereas the low-temperature Xe fraction (Xe-P3) typically has the normal isotopic composition. The paper presents a concise review of current models put forth to account for the genesis of nanodiamond with anomalous noble gas components and specifies a real process and major regularities during the generation of the isotopic relations of the anomalous Xe-HL component in relict nanodiamond grains. This component is demonstrated to be formed and captured simultaneously with the synthesis of nanodiamond, when shock waves induced by supernova explosions propagated. It is important that diamond synthesis during the passage of shock waves and the enrichment of this diamond in Xe-HL are also possible in the wave forefront region under extremal P-T conditions, in the pressure drop region behind the wave front (by means of nucleation), and by means of irradiation of carbonic grains with high-energy particles. The isotopic composition of Xe-HL results from an increase in the hardness of the spectrum of nuclear-active particles and its enrichment in heavy ions at acceleration in shock waves. Arguments are presented in support of the hypothesis that the nanodiamond population found in chondrites was produced during the latest supernova explosion before the development of the Solar System, with the supernova likely being a SnIa carbon detonation supernova. This furnishes evidence in support of recently advanced hypotheses that the nanodiamond population of chondrites is not presolar.
Diamond rain falls on Saturn and Jupiter. Diamonds big enough to be worn by Hollywood film stars could be raining down on Saturn and Jupiter, US scientists have calculated.
Abstract: This study gives an analysis of the effect of high temperature annealing on the infrared and photoluminescence (PL) features as well as the inclusions of two hydrogen-rich diamond plates from Zimbabwe that were cut from the same rough. The samples showed strong inclusion-related zoning known as hydrogen clouds which consist of micron-sized particles of as yet undetermined structure. This allowed hydrogen-rich and hydrogen-poor areas to be compared throughout the annealing study. The diamond plates were annealed to temperatures of 300oC, 600oC, 800oC, 1000oC, 1400oC, and 1700oC. The infrared and PL, and Raman maps were collected after every temperature step to study the effects of heat on the defects, and photomicrographs were collected to study the inclusions. Several photoluminescence features were seen to decrease in size including the 637 nm peak, which is the negatively charged nitrogen-vacancy center [NV-] and the 503.2 nm peak, known as the H3 and consists of two nitrogen atoms and vacancy in the neutral charge state and normally has a high thermal stability. The H2 defect at 986.2 nm, which is the negative form of the H3, was shown to increase after annealing. The hydrogen clouds underwent dramatic changes in apparent color and particle size, going from a light translucent gray appearance to an opaque black. The particle size grew from less than one micron to an average of fourteen microns, and the hexagonal outline of the particles became noticeable. Spatial raman spectroscopy was used to show that the color change and size change were due to graphitization of the included particles.
Abstract: Blue diamonds are among the rarest and most valuable of naturally occurring gemstones. In this study, 12 rough naturally-sourced type IIb diamonds were subjected to HPHT annealing, three different irradiation energies, and then all were stepwise annealed from 200 °C to 1100 °C and the optical defects were documented by changes in phosphorescence and photoluminescence spectroscopy. Several optical features that are removed from natural type IIb diamonds by HPHT processing, such as 3H, 648.2 nm peak, 776.4 nm peak, and 660 nm band (red) phosphorescence, can be reintroduced into these diamonds with subsequent electron irradiation and annealing at low-to-moderate temperatures. The thermal stability of these centers along with their spatial distribution provided additional insights into their configuration and distinguished them from nitrogen-bearing diamonds.
Physics and Chemistry of Minerals, in press available 10p.
Technology
Impact diamond
Abstract: High-resolution transmission electron microscopy was applied for the detailed nanostructural investigation of Popigai impact diamonds with the aim of revealing the nature of the amorphous carbon of the matrix. The successful application of two complementary specimen preparation methods, focused ion beam (FIB) milling and mechanical cleavage, allowed direct imaging of nanotwinned nanodiamond crystals embedded in a native amorphous carbon matrix for the first time. Based on its stability under the electron beam, native amorphous carbon can be easily distinguished from the amorphous carbon layer produced by FIB milling during specimen preparation. Electron energy loss spectroscopy of the native amorphous carbon revealed the dominance of sp2-bonded carbon and the presence of a small amount of oxygen. The heterogeneous size distribution and twin density of the nanodiamond crystals and the structural properties of the native amorphous carbon are presumably related to non-graphitic (organic) carbon precursor material.
Abstract: Type Ib diamonds contain abundant isolated nitrogen and account for less than 0.1% of natural diamonds. This rarity is because over geological time and at temperatures typical of the cratonic lithosphere, isolated nitrogen aggregates to A centres (N pairs) and B centres (4N around a vacancy). Preservation of isolated nitrogen in natural diamonds requires either short mantle residency times or storage at temperatures <700 °C, whereas most cratonic diamonds are billions of years old and resided >1000 °C. Eclogitic sulphides in Zimmi Ib diamonds (Sierra Leone) have 650 Ma Re-Os ages, whose origin is best explained by rapid tectonic exhumation after continental collision to shallower depths in the keel prior to kimberlite eruption (Smit et al., 2016). Here we present SIMS and spectroscopic data for a new suite of Zimmi sulphide-bearing diamonds. These new data allow us to evaluate the speciation of diamond source fluids, and the defects in these diamonds that are responsible for their distinctive canary yellow colours. The combined dataset establishes the link between the spectroscopic features in Zimmi Ib diamonds and their unusual history. Low ?13C values below -15 ‰ in 3 diamonds result from source fluids that originated as organic carbon in the oceanic crust, and were recycled into the lithosphere during subduction. In particular, a trend of decreasing ?13C and N content from core to rim in a single diamond indicates closed-system growth from CH4-rich subducted fluids. Recycled origins for organic carbon supports the temporal link of Zimmi diamond formation with deep underthrusting during Neoproterozoic continental assembly, recorded in the Rokelide orogen. CL imaging of Zimmi diamonds reveals irregular growth patterns with abundant deformation lines, associated with tectonic exhumation of the diamonds. Vacancies formed by deformation were subsequently annealed to form NV centres, where the negative charge state (637 nm) is more abundant due to isolated nitrogen donating an electron. Fancy brownish-yellow to greenish-yellow colours observed in Zimmi Ib diamonds result from a combination of isolated nitrogen, deformation-related amber centres and NV centres. These colour-forming defects can all be attributed to the unique geological history of Zimmi Ib diamonds and their rapid exhumation after formation.
A sublithospheric mantle, metallic liquid origin for the world's largest gem-quality diamonds.
GSA Annual Meeting, Abstract, 1p.
Technology
Type II diamonds
Abstract: Many of the world’s largest and most valuable diamonds (e.g. Cullinan, Lesedi La Rona, Star of Sierra Leone, Lesotho Promise, Koh-i-Noor) have an unusual set of physical characteristics, suggesting they may form by a unique and common mechanism. The most often noted characteristic is their nitrogen-deficient character, classifying them as Type II. In addition, these large diamonds are generally inclusion poor, irregularly shaped, and highly resorbed. The famous 3106 carat Cullinan diamond, discovered in 1905, is a prime example. These Cullinan-like Type II diamonds are especially valuable as gemstones and difficult to access for research. Furthermore, they very rarely contain any inclusions that might shed light on their geological origin. For these reasons the paragenesis of such diamonds has long remained so enigmatic that they have not been connected to the processes that form more common Type I diamonds or even any other Type II diamonds. Here we report the findings of a systematic search for inclusions among thousands of high-quality Type II diamonds, both polished gemstones and offcuts. Not only was the search successful in finding inclusions in 70 diamonds, it also revealed a recurring set of inclusions that are distinct from those of more familiar lithospheric/sublithospheric diamonds. The most abundant inclusion encountered was a metallic, Fe-Ni-C-S multi-phase assemblage, which was observed in 35 diamonds. The second most abundant inclusion type is former CaSiO3 perovskite, now retrogressed to lower-pressure minerals. The CaSiO3 phases constrain the depth of formation to deeper than 300 km. Two additional Cullinan-like Type IIa diamonds were found to have inclusions of low-Cr majoritic garnet, also indicative of a sublithospheric origin. Overall, the inclusions suggest that Cullinan-like, large, high-quality diamonds belong to a unique paragenesis with an intimate link to Fe-Ni metal in the deep mantle.
Abstract: Many of the world’s largest and most valuable diamonds (e.g. Cullinan, Lesedi La Rona, Star of Sierra Leone, Lesotho Promise, Koh-i-Noor) have an unusual set of physical characteristics, suggesting they may form by a unique and common mechanism. The most often noted characteristic is their nitrogen-deficient character, classifying them as Type II. In addition, these large diamonds are generally inclusion poor, irregularly shaped, and highly resorbed. The famous 3106 carat Cullinan diamond, discovered in 1905, is a prime example. These Cullinan-like Type II diamonds are especially valuable as gemstones and difficult to access for research. Furthermore, they very rarely contain any inclusions that might shed light on their geological origin. For these reasons the paragenesis of such diamonds has long remained so enigmatic that they have not been connected to the processes that form more common Type I diamonds or even any other Type II diamonds. Here we report the findings of a systematic search for inclusions among thousands of high-quality Type II diamonds, both polished gemstones and offcuts. Not only was the search successful in finding inclusions in 70 diamonds, it also revealed a recurring set of inclusions that are distinct from those of more familiar lithospheric/sublithospheric diamonds. The most abundant inclusion encountered was a metallic, Fe-Ni-C-S multi-phase assemblage, which was observed in 35 diamonds. The second most abundant inclusion type is former CaSiO3 perovskite, now retrogressed to lower-pressure minerals. The CaSiO3 phases constrain the depth of formation to deeper than 300 km. Two additional Cullinan-like Type IIa diamonds were found to have inclusions of low-Cr majoritic garnet, also indicative of a sublithospheric origin. Overall, the inclusions suggest that Cullinan-like, large, high-quality diamonds belong to a unique paragenesis with an intimate link to Fe-Ni metal in the deep mantle.
Abstract: Yakutites are coarse (up to 15 mm or larger) aggregates dispersed for more than 500 km around the Popigai meteorite crater. They share many features of similarity with impact diamonds found inside the crater, in elemental and phase compositions, texture, and optical properties as revealed by X-ray photoelectron spectroscopy, X-ray diffraction, and optical spectroscopy (Raman, absorption, luminescence and microscopic) studies. The N3 vibronic system appearing in the luminescence spectra of Popigai impact diamonds (PIDs) indicates a presence of nitrogen impurity and a high-temperature annealing of diamonds that remained in the crater after solid-phase conversion from graphite. Yakutites lack nitrogen-vacancy centers as signatures of annealing, which may indicate quenching at the time of ejection. Thus, both PIDs and yakutites originated during the Popigai impact event and yakutites were ejected to large distances.
Physics and Chemistry of Minerals, Vol. 43, 9, pp. 661-670.
Russia
Impact diamonds
Abstract: High-resolution transmission electron microscopy was applied for the detailed nanostructural investigation of Popigai impact diamonds with the aim of revealing the nature of the amorphous carbon of the matrix. The successful application of two complementary specimen preparation methods, focused ion beam (FIB) milling and mechanical cleavage, allowed direct imaging of nanotwinned nanodiamond crystals embedded in a native amorphous carbon matrix for the first time. Based on its stability under the electron beam, native amorphous carbon can be easily distinguished from the amorphous carbon layer produced by FIB milling during specimen preparation. Electron energy loss spectroscopy of the native amorphous carbon revealed the dominance of sp2-bonded carbon and the presence of a small amount of oxygen. The heterogeneous size distribution and twin density of the nanodiamond crystals and the structural properties of the native amorphous carbon are presumably related to non-graphitic (organic) carbon precursor material.
Diamond and Related Materials, Vol. 72, pp. 87-93.
Technology
Diamonds - type 11b
Abstract: Precision admittance spectroscopy measurements were carried out over wide temperature and frequency ranges for a set of natural single crystal type IIb diamond samples. Peaks of conductance spectra vs. temperature and frequency were used to compute the Arrhenius plots, and activation energies were derived from these plots. The capacitance-voltage profiling was used to estimate the majority charge carrier concentration and its distribution into depth of the samples. Apparent activation energies between 315 and 325 meV and the capture cross section of about 10? 13 cm2 were found for samples with uncompensated boron concentrations in the range of 1 to 5 × 1016 cm? 3 (0.06-0.3 ppm). The obtained boron concentrations are in good coincidence with FTIR results for the samples. Also, a reason for the difference between the observed admittance activation energy and the previously reported ionization energy for the acceptor boron in diamond (0.37 eV) is proposed.
Abstract: The petrographic study of two samples (quartzite and impactite) of Cerro León, a mountain range located in the middle of very probable impact basins (Cerro Leon-1, 2, 3 and 4-department of Alto Paraguay, Western-Paraguay) indicated evidences of impact metamorphism: PDFs (Not decorated and decorated) and diaplectic glass. Associated with diaplectic glass, impact diamonds or diamond/lonsdaleite crystals (micro and small macros) were observed with a range of morphologies including isolated and mostly agglutinated crystal varieties. Impact diamonds estimated to have formed by carbonate impact metamorphism present in the sedimentary target-rock of the Silurian/Devonian age. The identification of elements that reveal the impact metamorphism, in the analyzed samples of the Cerro León, evidences that the area of occurrence that would have been indicated as Very Probable Impact Basin, would be more of an Impact Basin.
Abstract: The finite element method is used to simulate the steady-state temperature field in diamond synthesis cell. The 2D and 3D models of the China-type cubic press with large deformation of the synthesis cell was established successfully, which has been verified by situ measurements of synthesis cell. The assembly design, component design and process design for the HPHT synthesis of diamond based on the finite element simulation were presented one by one. The temperature field in a high-pressure synthetic cavity for diamond production is optimized by adjusting the cavity assembly. A series of analysis about the influence of the pressure media parameters on the temperature field are examined through adjusting the model parameters. Furthermore, the formation mechanism of wasteland was studied in detail. It indicates that the wasteland is inevitably exists in the synthesis sample, the distribution of growth region of the diamond with hex-octahedral is move to the center of the synthesis sample from near the heater as the power increasing, and the growth conditions of high quality diamond is locating at the center of the synthesis sample. These works can offer suggestion and advice to the development and optimization of a diamond production process.
Abstract: There are four main types of natural diamonds and related formation processes. The first type comprises the interstellar nanodiamond particles. The second group includes crustal nano- and micron-scale diamonds associated with coals, sediments and metamorphic rocks. The third one includes nanodiamonds and microndiamonds associated with secondary alteration and replacing of mafic and ultramafic rocks. The fourth one includes macro-, micron- and nano-sized mantle diamonds which are associated with kimberlites, mantle peridotites and eclogites. Each diamond type has its specific characteristics. Nano-sized diamond particles of lowest nanometers in size crystallize from abiotic organic matter at lower pressures and temperatures in space during the stages of protoplanetary disk formation. Nano-sized diamonds are formed from organic matter at P-T exceeding conditions of catagenesis stage of lithogenesis. Micron-sized diamonds are formed from fluids at P-T exceeding supercritical water stability. Macrosized diamonds are formed from metal-carbon and silicate-carbonate melts and fluids at P-T exceeding 1150 °C and 4.5 GPa. Nitrogen and hydrocarbons play an important role in diamond formation. Their role in the formation processes increases from macro-sized to nano-sized diamond particles. Introduction of nitrogen atoms into the diamond structure leads to the stabilization of micron- and nano-sized diamonds in the field of graphite stability.
Abstract: Large and relatively pure diamonds like the historic 3,106 ct Cullinan, found in South Africa in 1905, have long been regarded as unusual based on their physical characteristics. For example, they often exhibit exceptional color and clarity, while routinely qualifying as type IIa, a rare designation of chemical purity. A new research discovery about these Cullinan-like diamonds is that they contain heretofore unknown, deeply derived inclusions that originate below the continental mantle keel and are thus known as "superdeep" diamonds (Smith et al., 2016). Originating from a depth between 360 and 750 km, they reveal information about the conditions within the convecting mantle, beneath the earth’s rigid tectonic plates. Here we review the previously published findings, compare the Cullinan-like diamonds to the more abundant lithospheric diamond population, and offer evidence from some additional diamond samples that further verifies their superdeep origin. Cullinan-like diamonds contain minute and rare silicate and iron-rich metallic inclusions surrounded by a fluid jacket composed of methane and hydrogen. The inclusion compositions suggest that this deep mantle environment contains small pockets of oxygen-deficient metallic liquid out of which the diamonds crystallized. This new and unexpected observation made on the world’s most expensive diamonds is important for understanding the chemical reactions between mineral assemblages in the deep earth. It shows that deep regions of the mantle contain metallic iron, as opposed to the shallower, more oxidized mantle rocks actively participating in plate tectonics and its associated volcanism.
Abstract: This paper presents a method for determination of the size distribution for diamond nanocrystals containing luminescent nitrogen-vacancy (NV) centers using the luminescence intensity only. We also revise the basic photo physical properties of NV centers and conclude that the luminescence quantum yield of such centers is significantly smaller than the frequently stated 100\%. The yield can be as low as 5\% for centers embedded in nanocrystals and depends on their shape and the refractive index of the surrounding medium. The paper also addresses the value of the absorption cross-section of NV centers.
Abstract: Several interstellar environments produce 'anomalous microwave emission', with brightness-peaks at tens-of-gigahertz frequencies. The emission's origins are uncertain - rapidly-spinning nano-particles could emit electric-dipole radiation, but polycyclic aromatic hydrocarbons proposed as the carrier are now found not to correlate with Galactic signals. The difficulty is to identify co-spatial sources over long lines of sight. Here we identify anomalous microwave emission in three proto-planetary discs. These are the only known systems that host hydrogenated nano-diamonds, in contrast to very common detection of polycyclic aromatic hydrocarbons. Spectroscopy locates the nano-diamonds close to the host-stars, at physically-constrained temperatures. Developing disc models, we reproduce the emission with diamonds 0.75-1.1 nanometres in radius, holding less than or equal to 1-2 per cent of the carbon budget. The microwave-emission:stellar-luminosity ratios are approximately constant, allowing nano-diamonds to be ubiquitous but emitting below detection thresholds in many star-systems. This can unify the findings with similar-sized diamonds found within solar system meteorites. As nano-diamond spectral absorption is seen in interstellar sightlines, these particles are also a candidate for generating galaxy-scale anomalous microwave emission.
81st Annual Meeting of the Meteoritical Society 2018, LPI contribution No. 2067, 1p. Abstract
Russia
diamond - impact
Abstract: Impact diamonds are known as high quality technical material [1]. Usually they are formed by graphite-to-diamond solid-phase diffuse-less transition at shock pressures > 30 GPa. The diffuse-less mechanism had been proven by numerous experimental studies [2]. But impact diamond formation is possible from non-graphitic precur-sor too, from amorphous carbons and bitumenes, while the process is rare known and slightly studied. In the nature not only graphite of metamorphic rocks but sedimentary organic matter containing rocks can be treated by impact processes resulting by high pressure phases up to after-coal diamond formation [3]. The only two astroblemes with after-coal diamonds have been found by present - the giant Kara and Ust`-Kara astroblemes with 65 and 25 km in diameters correspondently [1, 3]. The novel data on impact diamonds and impact objects are very actual since the practical interest to impact diamonds last time is rising [4, 5]. Here we present the after-coal diamonds features including a new impact diamond variety (Fig. 1) presented by after-organics diamond paramorphs first time found at the Kara astrobleme (Pay-Khoy, Russia) [6]. The paramorphs are characterized with perfectly preserved micromorphology of the wood relics being composed of pure carbon content with polynanocrystalline structure has been proven with Raman spectroscopy, transmission electron microscopy, atomic force microscopy and other modern methods. The received data on after-coal diamonds point to their formation by low-distance diffuse mechanism described for low ordered carbons by Borimchuk et al. [7]. The received data allow to present a new impact diamond variety widely spread through the Kara astrobleme counting huge concentrations - up to several thousand carat per ton [6]. The proposed novel mechanism of impact diamonds formation is characterized with several stages including high pressure high temperature fast pyrolysis with the precursor carbonization co-followed with diamond crystallization through low-distance diffuse mechanism [6]. The provided study allow suppose possibility of wide distribution of impact diamonds formed after noncrystalline carbons and organics of sedimentary objects at large impact craters around the world.
Abstract: Geological pathways for the recycling of Earth’s surface materials into the mantle are both driven and obscured by plate tectonics1,2,3. Gauging the extent of this recycling is difficult because subducted crustal components are often released at relatively shallow depths, below arc volcanoes4,5,6,7. The conspicuous existence of blue boron-bearing diamonds (type IIb)8,9 reveals that boron, an element abundant in the continental and oceanic crust, is present in certain diamond-forming fluids at mantle depths. However, both the provenance of the boron and the geological setting of diamond crystallization were unknown. Here we show that boron-bearing diamonds carry previously unrecognized mineral assemblages whose high-pressure precursors were stable in metamorphosed oceanic lithospheric slabs at depths reaching the lower mantle. We propose that some of the boron in seawater-serpentinized oceanic lithosphere is subducted into the deep mantle, where it is released with hydrous fluids that enable diamond growth10. Type IIb diamonds are thus among the deepest diamonds ever found and indicate a viable pathway for the deep-mantle recycling of crustal elements.
Abstract: Fourier transform infrared spectroscopy (FTIR) is highly sensitive to the surface chemistry of nanodiamonds. In this review, we discuss the different FTIR methods available to characterize nanodiamonds and highlight their advantages and limitations. We also summarize the possible assignments of FTIR spectra of nanodiamonds reported in the literature and discuss FTIR spectra of nanodiamonds modified by different surface treatments. Current work of FTIR applied to in situ and operando characterization of nanodiamonds, in particular nanodiamonds exposed to water or characterized during electrochemical and photocatalytic processes, are also discussed. Finally, perspectives regarding possible future FTIR development for nanodiamonds characterization are proposed.
Mineralogy and Petrology, in press available doi.org/10.1007/ s00710-019-00671-1 10p.
Russia
impact diamonds
Abstract: Complementary nano- and atomic-scale data from SEM, FIB, HRTEM, and EELS observations of after-coal impact diamonds from the giant Kara astrobleme are described, presenting their particular nano-sized porous polycrystalline structure, which consists of well-shaped single 20-30 nm nanocrystals that are free of deformation defects and do not contain lonsdaleite. The porous micro- and nanostructure is a special typomorphic feature of after-coal diamonds that suggests a crystallisation mechanism through short distance diffusion. The data for the after-coal impact diamonds presented here demonstrate their distinguishing characteristics from after-graphite impact diamonds, and have some similarity with the enigmatic carbonado, providing new insights to the origin of the latter
Abstract: Although the phonon confinement model (PCM) was claimed to be successfully used to accurately calculate the size of larger Si nanocrystals, quantitative size characterization by Raman spectra still remains a challenge in the case of nanodiamonds due to its complexity. Here, we find that a local-mode model of Raman spectra developed recently can be employed to determine the bond number of the ordered diamond core in nanodiamonds, and then furtherly determine the size of nanodiamonds. The Raman lines of nanodiamonds of 3.0?nm, 2.0?nm, 2.2?nm, 3.3?nm, 3.7?nm 4.42?nm and 6.3?nm are calculated. Results are in good agreement with the measured Raman spectra. It not only provides a new approach to predict the size of nanodiamonds accurately by Raman spectra, but also helps to clarify issues in Raman spectra of nanodiamond and other carbon nanomaterials.
Angewandte Chemie International edition, Vol. 58, 50, pp. 17918-17929.
Global
nanodiamond
Abstract: Nanodiamond(ND)?based technologies are flourishing in a wide variety of fields spanning from electronics and optics to biomedicine. NDs are considered a family of nanomaterials with an sp3 carbon core and a variety of sizes, shapes, and surfaces. They show interesting physicochemical properties such as hardness, stiffness, and chemical stability. Additionally, they can undergo ad?hoc core and surface functionalization, which tailors them for the desired applications. Noteworthy, the properties of NDs and their surface chemistry are highly dependent on the synthetic method used to prepare them. In this Minireview, we describe the preparation of NDs from the materials?chemistry viewpoint. The different methodologies of synthesis, purification, and surface functionalization as well as biomedical applications are critically discussed. New synthetic approaches as well as limits and obstacles of NDs are presented and analyzed.
Abstract: Impact diamonds are technical material with valuable mechanical properties. Despite of a quite long story from their discovery and huge diamond storages at the Popigai astrobleme (Siberia, Russia) they were not involved into industrial production, first of all because of remoteness of objects, complexity of extraction and economically more favourable synthesis of technical diamonds in the seventies of the past century. However, due to the high hardness of impact diamonds and also to the high demand of new carbon materials, including nanomaterials, the interest towards this type of natural diamonds is significantly increased in the recent years. Although the mentioned Popigai astrobleme is situated in a remote part of Russia it has been studied in more details. At the same time, the less known Kara giant meteorite crater (Pay-Khoy, Russia) is situated essentially closer to the industrial infrastructure of the European part of Russia. This astrobleme, similarly to Popigai, is enriched in impact diamonds as well. But, till recent years it was not deeply studied using modern analytical methods. During our studies in 2015 and 2017 at the territory of the Kara meteorite crater we have distinguished and described 5 varieties of impactites - bulk melt impactites which form cover-like and thick dike bodies; melt ultrahigh-pressure vein bodies and at least 3 types of suevites formed after specific sedimentary target rocks. These varieties have typomorphic features regarding the crystallinity and mineral composition. It was found that all of them have high concentration of microdiamonds formed by high-pressure high temperature pyrolysis mechanism from precursor materials like coal and organic relicts. Using a set of modern mineralogical methods we have found two principal types of diamond morphologies within the Kara impactites - sugar-like after coal diamonds and diamond paramorphs after organic relicts. The Kara diamonds have several accompanying carbon substances including newly formed graphite, glass-like carbon and probably carbyne. The studied diamondiferous Kara impactites provide an essentially novel knowledge of impact processes in sedimentary targets.
Doklady Earth Sciences, Vol. 489, 2, pp. 1449-1452 .pdf
Russia
diamond morphology, CLIPPIR
Abstract: The primary results are presented on the dissolution of plane-faced diamond crystals of octahedral habit in a Fe-Ni-S melt under 3.5 GPa and 1400°C. It was found that the dissolution resulted in the transformation of plane-faced into curve-faced individuals of morphological features characteristic for kimberlite diamonds. It was concluded that the diamond forms as such might have formed in reduced domains of the Earth’s mantle before becoming involved in the kimberlite magma.
Earth and Planetary Science Letters, Vol. 543, 116328 14p. Pdf
Europe, Switzerland, Alps
boron diamonds
Abstract: Understanding the volatile cycles at convergent margins is fundamental to unravel the Earth's evolution from primordial time to present. The assessment of fluid-mobile and incompatible element uptake in serpentinites via interaction with seawater and subduction-zone fluids is central to evaluate the global cycling of the above elements in the Earth's mantle. Here, we focus on the carbon (C), nitrogen (N) and C isotope compositions of chlorite harzburgites and garnet peridotites deriving from subduction-zone dehydration of former oceanic dehydration of serpentinite - i.e., metaperidotites (Cima di Gagnone, Swiss Central Alps) with the aim of evaluating the contribution of these rocks to the global C-N cycling. These ultramafic rocks, enclosed as lenses in a metasedimentary mélange, represent the destabilization of antigorite and chlorite at high-pressure/temperature (P/T) along a slab-mantle interface. Chlorite- and garnet-bearing rocks have similar ranges in C concentration ([C] = 210 - 2465 ppm and 304 - 659 ppm, respectively), with one magnesite-bearing chlorite harzburgite hosting 11000 ppm C. The average N concentrations ([N]) of the garnet peridotites (54 ± 15 ppm, one standard deviation indicated) are higher than those of the chlorite harzburgites (29 ± 6 ppm). The C of total C (TC) and total organic C (TOC) values of the Gagnone metaperidotites range from -12.2 to -17.8‰ and from -27.8 to -26.8‰, respectively, excluding the magnesite-bearing chlorite harzburgites with higher values of -7.2‰ (TC) and -21.2‰ (TOC). The [C] of these rocks are comparable to those of serpentinites form modern and ancient oceanic environments and with [C] of high-P serpentinites. However, the lack of preserved serpentinite precursors makes it difficult to determine whether release of H2O during high-P breakdown of antigorite and chlorite is coupled with significant C release to fluids. The C values appear to reflect mixing between seawater-derived carbonate and a reduced C source and a contribution from the host metasedimentary rocks ([C] = 301 ppm; [N] = 33 ppm; TC C = -24.4‰; TOC C = -27.0‰) cannot be completely excluded. The C-O isotope composition of the carbonate in magnesite-bearing chlorite harzburgites is compatible with progressive devolatilization at oxidized conditions, whereas the signatures of the majority of the other Gagnone samples appear to reflect different degree of interaction with sedimentary fluids. The [N] of the Gagnone metaperidotites are higher than those of oceanic and subducted serpentinites and show a range similar to that of high-P antigorite-serpentinites from mantle wedges. This enrichment is compatible with fluid-mediated chemical exchange with the surrounding metasedimentary rocks leading to strong modification of the Gagnone metaperidotites' geochemistry during prograde subduction along the slab-mantle interface. Comparing the C data reported in this study with published C values for diamonds, we suggest that the volatile recycling via Gagnone-like metaperidotites in subduction zones could contribute to deep-Earth diamond genesis and in particular to the formation of blue boron (B)-bearing diamonds. Our results highlight that the subduction of secondary peridotites evolved along the slab-mantle interface is a viable mechanism to inject volatiles into the deep mantle, particularly in hotter geothermal regimes such as the ones active during the early Earth's history.
Abstract: In the past few years, two new diamond varieties have been characterized as sublithospheric, or super-deep, in origin. Ongoing studies of new inclusion-bearing specimens continue to improve our understanding of type IIa (more specifically, CLIPPIR) and type IIb diamonds. CLIPPIR diamonds are a variety epitomized by large and high quality type IIa gem diamonds, such as the 3106 carat Cullinan diamond [1]. Among their inclusions are examples of majoritic garnet and inferred CaSiO3-perovskite, suggesting a formation depth in the range of 360 to 750 km [1, 2]. Type IIb diamonds (boron-bearing) host inclusions of ferropericlase as well as retrogressed majoritic garnet, CaSiO3-perovskite, CF-type phase, stishovite, and bridgmanite [3]. The mineral assemblage suggests an origin deeper than 360 km, likely in the transition zone to uppermost lower mantle. The relationship between these two similar diamond varieties remains somewhat unclear. Studies to date have left open the possibility that CLIPPIR diamonds might be formed at distinctly shallower depths than type IIb’s, without any overlap. An additional large (>100 carats) rough CLIPPIR diamond has now been examined that contains inclusions of retrogressed aluminous bridgmanite. This is the first evidence of CLIPPIR diamond growth in the lower mantle, meaning there must be some overlap between the depth of formation for CLIPPIR and type IIb diamonds. A related issue concerning depth of formation, for type IIb diamonds [4], has also been addressed by examination of a new specimen. A large (>10 ct) type IIb diamond has been found to contain former bridgmanite, which helps to dissolve the apparent dichotomy between inclusions in larger (>2ct) and smaller (<2ct) type IIb diamonds [4, 5]. These recently examined specimens are helping to build a clearer picture of the paragenesis and geochemical implciations of these exquisite gem diamonds.
Abstract: Natural diamonds can form through low pressure and temperature geological processes on Earth, as stated in an article published in the journal Geochemical Perspectives Letters. The newfound mechanism, far from the classic view on the formation of diamonds under ultra-high pressure, is confirmed in the study, which draws on the participation of experts from the Mineral Resources Research Group of the Faculty of Earth Sciences of the University of Barcelona (UB).
Abstract: Colloidal diamonds - stable, self-assembled material with promising applications in light-related technologies - can now be fabricated, decades after its concept was first developed in the 90s.
Abstract: Diamond is commonly regarded as an indicator of ultra-high pressure conditions in Earth System Science. This canonical view is challenged by recent data and interpretations that suggest metastable growth of diamond in low pressure environments. One such environment is serpentinisation of oceanic lithosphere, which produces highly reduced CH4-bearing fluids after olivine alteration by reaction with infiltrating fluids. Here we report the first ever observed in situ diamond within olivine-hosted, CH4-rich fluid inclusions from low pressure oceanic gabbro and chromitite samples from the Moa-Baracoa ophiolitic massif, eastern Cuba. Diamond is encapsulated in voids below the polished mineral surface forming a typical serpentinisation array, with methane, serpentine and magnetite, providing definitive evidence for its metastable growth upon low temperature and low pressure alteration of oceanic lithosphere and super-reduction of infiltrated fluids. Thermodynamic modelling of the observed solid and fluid assemblage at a reference P-T point appropriate for serpentinisation (350 °C and 100 MPa) is consistent with extreme reduction of the fluid to logfO2 (MPa) = ?45.3 (?logfO2[Iron-Magnetite] = ?6.5). These findings imply that the formation of metastable diamond at low pressure in serpentinised olivine is a widespread process in modern and ancient oceanic lithosphere, questioning a generalised ultra-high pressure origin for ophiolitic diamond.
Nano Letters, doi.10.1021/acs/ nanolett.Oc0556 10p. Pdf
Global
nanodiamond
Abstract: The search for new nanostructural topologies composed of elemental carbon is driven by technological opportunities as well as the need to understand the structure and evolution of carbon materials formed by planetary shock impact events and in laboratory syntheses. We describe two new families of diamond-graphene (diaphite) phases constructed from layered and bonded sp3 and sp2 nanostructural units and provide a framework for classifying the members of this new class of materials. The nanocomposite structures are identified within both natural impact diamonds and laboratory-shocked samples and possess diffraction features that have previously been assigned to lonsdaleite and postgraphite phases. The diaphite nanocomposites represent a new class of high-performance carbon materials that are predicted to combine the superhard qualities of diamond with high fracture toughness and ductility enabled by the graphitic units and the atomically defined interfaces between the sp3- and sp2-bonded nanodomains.
Geology of Ore Deposits, Vol. 62, 8, pp. 743-753. pdf
Russia, Urals
cuboid diamonds
Abstract: The internal structure and spectroscopic features of cuboid diamonds from recent alluvial placers of the Krasnovishersk District (the Urals) have been investigated. Crystals were divided into four groups by their anatomy and spectroscopy: cuboids of the II group (according to the Yu.L. Orlov classification): cuboids with a transparent core and peripheral zone saturated with inclusions; crystals with mixed habit growth of ?100? and ?111? pyramids, and crystals with the sequential growth of ?100? and ?111? pyramids. In all studied crystals, the regenerative formation of the {111} face steps together with the formation of tetragonal pits on the cuboid surface was the last stage of growth. Local photoluminescence investigations have been carried out for all cubic diamond crystals of the Urals for the first time. It was established that luminescence bands at 926 and 933 nm are related to growth pyramids of ?100? and ?111?, respectively. Bands with peaks at 800, 820.5, 840, 860, and 869 nm were revealed in the luminescence systems of the cuboids of II group. We note that the cuboid diamonds from different regions of the world have similar internal structures and spectroscopic features.
Journal of Materials Research and Technology, Vol. 12, pp. 1473-1485.
China
nanodiamonds
Abstract: In this work, Ni/diamond composite coatings have been synthesized by electrodeposition in direct current mode. The effects of mechanical and ultrasonic agitations on the microstructural, surface characteristics and electrochemical properties have been comparatively investigated by various methods. Results show that diamond nanoparticles have been evenly dispersed in Ni metallic matrix, which could reinforce their performances. The coatings prepared under ultrasonic and mechanical agitation both exhibit compact, dense and hill-valley like morphology with pyramid-like nickel crystallite grains. The relative texture coefficient (RTC) values show that the preferred orientation of the Ni/diamond coating was (200) texture. From 3 to 5 A dm?2, the crystallite sizes of ultrasonic conditions were 59.2-81.7 nm, which were smaller than 76.3-83.2 nm of magnetic agitations. The average roughness (Ra = 78.9-133 nm) of ultrasonic-assisted coatings were lower than 103-139 nm of magnetic conditions. The mechanism of the co-electrodeposition process was proposed. Electrochemical impedance spectroscopy (EIS) results illustrate that the ultrasonic-assisted electrodeposited Ni/diamond coating has better corrosion resistance than that prepared under mechanical stirring conditions. The Ni/diamond composite coatings could be applied as protective materials in harsh mediums.