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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Diamond - Treatment
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 - Treatment articles deal with the ways natural diamonds can be treated to enhance their visual gemological quality through means such as irradiation, heating (annealing) or inclusion removal and replacement . Treated diamonds are controversial because the system for valuing natural rough diamonds is based on the concept of relative scarcity. By applying technology to transform a relatively abundant type of diamond such as yellow or brown diamonds into a more desirable and rarer form, the scarcity valuation basis is undermined. The diamond treatment topic is related to the production of synthetic diamonds.
Investigating a new treatment - low pressure-high temperature is the latest development in diamond treatments. HPHT and Type II diamonds…now LPHT on larger quantity of diamonds. ( Colour enhancement)
GSA Annual Meeting, Paper 300-7, 1p. Abstract only Booth
Technology
HPHT
Abstract: Defects H3 and H4 are common in natural, HPHT treated, and artificially irradiated fancy colored diamonds. Understanding of their formation is important for color origin determination in gem labs. However, there are still substantial challenges. Davies (1972) studied the effect of different forms of nitrogen on the annealing of radiation damage, and found A/B = H3/H4. However, Collins (1982, 2001) pointed out that some natural type Ia diamonds could have H3 absorption but even when they contain substantial amounts of nitrogen in the B-form, the H4 absorption is negligible. In this study, based on investigation of a group of 39 (0.12 - 7.03 ct) natural green - yellow diamonds, vacancy source for formation H3 and H4 is identified and preference formation of H3 over H4 is discussed. Nitrogen concentrations of these diamonds fell in a range of 32- 496 ppm, with average 0.67 for B/(B+A). So, significant amount of B-form nitrogen exist. No irradiation feature of H1a, H1b, H1c, or 595 nm absorption was detected. Absorption spectra in the UV-Vis region were dominated by defects N3 and H3. Strong emission bands from H3 were observed, and its fluorescence substantially contributed to the body colors of green - yellow. As an outstanding feature, absorption or emission of defect H4 is entirely absent, despite significant concentrations of B-form nitrogen. Strong plastic deformation is a common feature in all samples. Green fluorescence from defect H3 clearly followed dislocation by showing up to 3 sets of parallel lines, instead of following growth zonation. These sharp lines are continuous throughout the whole stones. Strong dislocations indicated that these diamonds were originlly in brown color after the plastic deformation and thus with significant concentrations of vacancy clusters. Annealed in the earth’s mantle over a long geological history, single vacancies released from vacancy clusters could combine with the A-form nitrogen to form H3. Strong preference in forming H3 over H4 could be related to the unknown disaggregation process of vacancy clusters and the annealing in the earth’s mantle over long geological time. Absence of H4 in this type of diamonds could be considered as a useful indication of natural color origin.
Contributions to Mineralogy and Petrology, Vol. 170, pp. 41-
Mantle
HPHT
Abstract: We report first results of a systematic study of carbon isotope fractionation in a carbonate fluid system under mantle PT conditions. The system models a diamond-forming alkaline carbonate fluid using pure sodium oxalate (Na2C2O4) as the starting material, which decomposes to carbonate, CO2 and elementary carbon (graphite and diamond) involving a single source of carbon following the reaction 2Na2C2O4 ? 2Na2CO3 + CO2 + C. Near-liquidus behaviour of carbonate was observed at 1300 °C and 6.3 GPa. The experimentally determined isotope fractionation between the components of the system in the temperature range from 1300 to 1700 °C at 6.3 and 7.5 GPa fit the theoretical expectations well. Carbon isotope fractionation associated with diamond crystallisation from the carbonate fluid at 7.5 GPa decreases with an increase in temperature from 2.7 to 1.6 ‰. This trend corresponds to the function ?Carbonate fluid-Diamond = 7.38 × 106 T?2.
www.minsocam.org/ MSA/Centennial/ MSA_Centennial _Symposium.html The next 100 years of mineral science, June 20-21, p. 35. Abstract
Global
HPHT, CVD, synthetics
Abstract: Diamond growth technology has experienced rapid progress in the past 20 years. Gemquality diamonds can be produced with both HPHT (high-pressure and high-temperature) and CVD (chemical vapor deposition) technologies. While HPHT technology basically mimics the growth conditions of natural diamonds in the earth’s mantle, the CVD method actually grows diamond in graphite-stable thermodynamic conditions. Faceted gem diamonds, both colorless and fancy-colored, are commercially produced up to 20 carats, comparable to topquality natural diamonds. At the same time, millions of melee-size gem diamonds (0.005 carat and up) are produced for the gem trade. Post-growth treatments (mainly HPHT annealing and irradiation under a high-energy beam) can not only remove an undesirable brown color but also introduce many types of fancy colorations such as pink/red and blue. Millions of carats of synthetic gem diamonds are produced annually for the gem trade globally. It is very important for the jewelry industry to be able to effectively and accurately separate synthetic diamonds from natural. All diamonds have lattice defects, from ppm to ppb concentrations or even lower. Main defects include nitrogen, boron, vacancies, dislocations, and combinations of these. Natural diamonds and their synthetic counterparts are supposed to have different defect configurations, such as defect type, concentration, coexistence, and distribution within a single crystal. Sometimes this difference can be very minor. Artificial treatment could be applied to intentionally minimize the differences to reduce the possibility of identifying synthetics. Natural and synthetic diamonds have a fundamentally different growth habit. Natural diamonds are dominated by a {111} growth sector. HPHT synthetic diamonds normally have multiple growth sectors such as {111}, {100}, and {110}. CVD diamond typically grows in the {100} direction only, but the uneven growth rate creates striations. The ability to capture defects varies significantly among different growth sectors, which are considered the most reliable features in identification. In gem laboratories, a host of gemological and spectroscopic technologies have been developed to enable this separation. GIA’s laboratory can identify every single synthetic diamond produced. Details of the current status of synthetic gem diamonds and their identification will be reviewed in this presentation.
Chemical Reviews, Vol. 120, 4, 10.1021/ acs.chemrev.9b00578 50p. Pdf
Global
HPHT, CVD, synthetics
Abstract: Nitrogen is ubiquitous in both natural and laboratory-grown diamond, but the number and nature of the nitrogen-containing defects can have a profound effect on the diamond material and its properties. An ever-growing fraction of the supply of diamond appearing on the world market is now lab-grown. Here, we survey recent progress in two complementary diamond synthesis methods: high pressure high temperature (HPHT) growth and chemical vapor deposition (CVD), how each is allowing ever more precise control of nitrogen incorporation in the resulting diamond, and how the diamond produced by either method can be further processed (e.g., by implantation or annealing) to achieve a particular outcome or property. The burgeoning availability of diamond samples grown under well-defined conditions has also enabled huge advances in the characterization and understanding of nitrogen-containing defects in diamond alone and in association with vacancies, hydrogen, and transition metal atoms. Among these, the negatively charged nitrogen-vacancy (NV-) defect in diamond is attracting particular current interest in account of the many new and exciting opportunities it offers for, for example, quantum technologies, nanoscale magnetometry, and biosensing.
Physicsa Status Solidi , doi:10.1002/pssa.201900888
Global
HPHT
Abstract: Various samples of multisectoral high?pressure high?temperature (HPHT) single?crystal diamond plate (IIa type) (4?×?4?×?0.53?mm) are tested for particle detection applications. The samples are investigated by X?ray diffractometry, photoluminescence spectroscopy, Raman spectroscopy, Fourier?transform infrared, and visible/ultraviolet (UV) absorption spectroscopy. High crystalline perfection and low impurity concentration (in the {100} growth sector) are observed. To investigate detector parameters, circular 1.0 and 1.5?mm diameter Pt Schottky barrier contacts are created on {111} and {100} growth sectors. On the backside, a Pt contact (3.5?×?3.5?mm) is produced. The {100} growth sector is proved to be a high?quality detector: the full width at half maximum energy resolution is 0.94% for the 5.489?MeV 226Ra ??line at an operational bias of +500?V. Therefore, it is concluded that the HPHT material {100} growth sector is used for radiation detector production, whose quality is not worse than the chemical vapor deposition method or specially selected natural diamond detectors.