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1
Lin, Guan Fu, Ming Yi Tsai, and Chiu Yuan Chen. "Development of a Combined Diamond Impregnated Lapping Plate." Key Engineering Materials 739 (June 2017): 157–63. http://dx.doi.org/10.4028/www.scientific.net/kem.739.157.
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This paper presents a combined diamond-impregnated lapping plate for single crystal silicon carbide (SiC) to improve the material removal rate due to SiC having very low material removal rate. Three different dimaond shapes were prepared: (1) "sharp," a sharp-edged diamod; (2) "blocky," a high quality crystalline diamond; (3) "oxidized diamond". The diamonds were manufactured by using high temperature heating method in a furnace to induce diamond oxidation resulting in improvement of Ra and sharpness of the diamonds. Three combined diamond-impregnated lapping plates were fabricated using the above mentioned diamond shapes with diamond size of 6μm. The surface roughness and removal rate of the SiC lapping with these plate were investigated. Experimental results showed that the average material removal rate (MRR) of oxidized diamond is higher than that of the other diamond shapes. The MRR of oxidized diamond for C-face and Si-face SiC are 4.72μm/hr and 6.26μm/hr, respectively. It is found that the surface roughness (Ra) of oxidized diamond for C-face and Si-face are 7.547nm and 8.06nm, respectively. This indicates that the combined diamond-impregnated lapping plate can be effectively used for SiC machining.
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Muhammad Basysyar, Fadhil, and Gifthera Dwilestari. "COMPARISON OF MACHINE LEARNING ALGORITHMS FOR PREDICTING DIAMOND PRICES BASED ON EXPLORATORY DATA ANALYSIS." International Journal of Engineering Applied Sciences and Technology 7, no. 5 (September 1, 2022): 71–79. http://dx.doi.org/10.33564/ijeast.2022.v07i05.012.
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Diamonds are a unique commodity whose socially generated notions significantly influence perceived value. To study how a diamond's physical attributes might predict its price, a massive dataset of loose diamonds scraped from an online diamond store is subjected to data mining, which reveals that diamond weight, color, and clarity are the most influential determinants of diamond pricing. Therefore, submit a proposal for an Exploratory Data Analysis that includes a component that analyses various parts of news articles using LASSO Regression, ElasticNet Regression, and Random Forest Regression. This system is trained on past data to forecast diamond prices while retaining an easily interpretable trading approach concerning rule complexity. The suggested strategy beats cutting-edge methods for prediction accuracy and interpretability, such as extreme learning machines using deep learning. Our data indicate that the news impact factor is crucial for forecasting. Demonstrate that the suggested system outperforms the average yearly return while offering a set of language trading rules that are interpretable. This has substantial repercussions for investors. A significant degree of subjectivity in diamond pricing may result from diamond dealers' price concealment techniques.
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Liu, Fu-Kang, Ying Guo, Bei Zhao, and Xiang Li. "The Color Origin and Evaluation of Natural Colored Diamonds." Science of Advanced Materials 14, no. 2 (February 1, 2022): 243–56. http://dx.doi.org/10.1166/sam.2022.4210.
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Diamond is widely concerned and loved by people due to its rarity, beauty and beautiful implication in love. Color is very important in colored diamonds’ evaluation, and diamonds are extremely colorful. Scholars have done some researches on the color origin of colored diamonds, but the types of diamonds studied are not comprehensive, and the influence of these color origins on diamonds’ color evaluation has not been systematically clarified. Therefore, this paper focuses on the color of diamonds, arranges a large number of documents, and systematically summarizes and discusses the color and evaluation of colored diamonds. Firstly, the five color systems on which the description of diamond color depends, including principles, advantages and limitations, are described and compared. Then, the types and action mechanism of all color origins of colored diamonds are expounded in detail and comprehensively. In addition, the influence of factors other than the characteristics of diamond itself on diamond’s color evaluation are discussed, including cutting, fluorescence and phosphorescence. Finally, the intelligent color evaluation of colored diamonds is prospected, which will be widely used in the future. And this review will provide reference for the color evaluation of other colored gemstones.
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Xu, Jingru. "Prediction on the Prices of Laboratory-Grown Diamonds based on Multiple Linear Regression Model." Highlights in Business, Economics and Management 35 (June 16, 2024): 101–7. http://dx.doi.org/10.54097/8yaq7c77.
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Diamond as emotional investment, in recent years, the market price of it is going through rising and falling, and drastic fluctuating, more is the decline in price. The diamond industry has also been challenged, there is happening oversupply and weak demand in diamond market. The impact of lab-grown diamonds on natural diamonds has also changed the price of diamonds across the diamond industry. However, the market of diamond is still at the forefront of the jewelry industry. In order to ensure that consumers have more understanding of diamond choices, this paper adopts multiple linear regression model to forecast diamond prices, collects a large amount of data, and uses 4c criteria as the standard for diamond price prediction to explore the relationship between diamond prices and diamond measurement standards. Through the calculation, the diamond buyers will explore ways to realize diamond price, the diamond industry will be rationalized production, and balance the relationship between diamond supply and demand to provide a method.
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Jaskie, James E. "Diamond-Based Field-Emission Displays." MRS Bulletin 21, no. 3 (March 1996): 59–64. http://dx.doi.org/10.1557/s0883769400036149.
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Diamond has existed in the natural state for thousands of years. It was mainly used as a jewel for its optical brilliance and for its hardness. In the 1950s methods were developed to fabricate synthetic diamonds commercially. This greatly increased diamond's industrial use, mostly for grinding and lapping applications. Diamond is a crystalline form of carbon, a group-IV element in the periodic table. Silicon and germanium are also Group-IV elements and also have the same crystalline lattice structure as diamond. Hence there has been theoretical interest in diamond's electronic properties since the beginning of the semiconductor age. However the cost and poor crystalline quality of both natural and synthetic diamond have precluded any real industrial interest in diamond as an electronic material. Methods of low-temperature and low-pressure diamond-film deposition, developed initially by the Russians in the 1950s and 1960s (and thence by the Japanese, and eventually by others) has made it possible to use this exotic material as an electronic substrate.Diamond, in single-crystalline, polycrystalline, and diamondlike carbon (DLC) forms, is a material with many unusual properties. It is the hardest naturally occurring material, the most thermally conductive, and the most transparent. It also has the slickness of Teflon. In regard to many physical properties, it is at the extreme end of the scale. One of the more unusual and important properties that it possesses is its presentation of a rather small barrier to the emission of electrons into a vacuum.
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Seo, Jin Kyo, Jeong Hwan Lee, and Jong Wan Park. "Comparison of Natural Type Ia Diamond and CVD Diamond Films by Photoluminescence." Solid State Phenomena 124-126 (June 2007): 467–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.467.
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The crystal defects in diamonds are diverse. In other words, there are almost no perfect diamonds without impurities or dislocations. Most natural diamonds contain a considerable amount of nitrogen impurity in aggregated forms. CVD diamond films also included many crystal defects. We investigated the distribution of luminescence center of natural type Ia diamonds and CVD diamond films by various photoluminescence excitation source. Photoluminescence (PL) spectroscopy is a useful technique to provide information on defects of diamond with high sensitivity.
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Polushin, Nikolay Ivanovich, Alexander Ivanovich Laptev, Mariya Stanislavovna Shitareva, Dmitry Sergeevich Muratov, Anatoly Lvovich Maslov, Alexey Nikolaevich Kirichenko, Sergey Alexeevich Perfilov, and Tatiana Vladimirovna Martynova. "The use of spectroscopy methods for structural analysis of CVD diamond films, polycrystalline and single-crystal diamonds." MATEC Web of Conferences 336 (2021): 01013. http://dx.doi.org/10.1051/matecconf/202133601013.
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For the work results correct interpretation, it is important to study initial materials that scientists have to deal with. Currently, there are a large number of different diamond substrates. Comparison of materials among themselves allows you to determine which material you are dealing with. In this work, the methods of infrared (IR) spectrometry, Raman spectroscopy and spectrophotometry are used to study four types of diamond materials: diamond polycrystalline CVD-films; natural single-crystal diamonds; synthetic polycrystalline HPHT-diamonds (such as DSPC – diamond synthetic polycrystal by GOST 9206-80); polycrystalline CVD-diamonds CDM manufactured by E6. In work it was shown that the Raman spectroscopy allows to measure the effect of heat treatment on changes in the diamond structure, even if it is such highly advanced diamond materials as natural diamonds. Heat treatment affects the perfection of diamond crystal structure by reducing stresses and the number of defects in it due to graphitization process. The IR spectrometry method is effective for determining the shape and amount of nitrogen inclusions in diamond structure. To study polycrystalline CVD-films, the spectrophotometry method turned out to be the most effective, because it made possible to determine a small number of nitrogen defects and draw conclusions about the quality of the films. The investigation of polycrystalline diamonds CDM and DSPC demonstrated that, despite their coarse-crystalline structure, diamond crystallites consist of a highly defective diamond phase; in addition, DSPC-diamonds were studied using this method in the first time.
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Karpovich, Z. A., E. I. Zhimulev, and A. I. Chepurov. "Growth Diamond on an Impact Lonsdaleite-bearing Diamond from the Popigai Astrobleme." Bulletin of Irkutsk State University. Series Earth Sciences 38 (2021): 41–53. http://dx.doi.org/10.26516/2073-3402.2021.38.41.
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The Popigai astrobleme contains huge reserves of diamonds with unusual properties. In impact diamonds from the Popigai astrobleme, the cubic phase and lonsdaleite are intergrown. In order to study the relationship of lonsdaleite-bearing impact diamonds with diamond, an experimental study of the features of diamond growth on lonsdaleite-bearing fragments was carried out. The experiments were carried out on a high-pressure apparatus of the “BARS” type at 5.5 GPa and 1450 ° C in the Fe-Ni-C system (nickel 36 wt.%). Impact Popigai diamonds were used as seed crystals. As a result of the study, it was found that the newly formed crystals are represented by a cubic phase, while the lonsdaleite in the seed crystals was preserved and the lonsdaleite / diamond ratio did not change. The newly formed cubic diamond in its main properties (Raman spectra, morphology, color, etc.) corresponds to synthetic diamonds grown in the iron-nickel system. The difference between the growth of crystals on seeds of impact diamonds and growth on a single-crystal seed of diamond was that the nucleation of crystals began from different points of the seed of the impact diamond. Multi-headed growth was observed and, as a result, an intergrowth of diamond crystals was formed. Probably, the initial misorientation of the points of nucleation of subindividuals leads to multi-headed growth of crystals in an intergrowth, in contrast to single-crystal growth of diamond on a single- crystal seed.
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Segl, Jakob, and Christian Edtmaier. "Influence of the Diamond Surface Termination on the Thermal Conductivity of Al/Diamond- and Ag/Diamond MMCs." Materials Science Forum 825-826 (July 2015): 142–49. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.142.
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MMCs consisting of diamonds and highly conductive metal matrices have been produced via gas pressure assisted liquid metal infiltration and their thermal properties have been investigated. Special attention was paid towards the diamond surface termination and its influence on the diamond-metal-interface and the resulting heat transport across this interface. Altering the diamond terminating surface layer can lead to a rather drastic increase in the thermal conductivity, rendering MMCs with pretreated diamonds double the thermal conductivity of the ones with as-received diamonds. The evolution of those terminating layers with different pretreatment conditions and their influence on the thermal conductivity of the resulting MMCs is rather complex and an ever-growing field of interest for diamond heat sink materials.The observed thermal properties of the MMCs produced in this study will be linked with the established diamond surface termination and will demonstrate the potential that lies within the method of diamond surface modification.
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Valerii, Lavrinenko, Solod Volodymyr, Ilnytska Halina, Smokvyna Volodymyr, and Kashynskiy Ivan. "RESEARCH OF THERMAL INFLUENCE ON THE CHANGE OF THE SURFACE LAYER OF DIAMONDS AND ASSOCIATED TOOL MATERIALS (REVIEW)." Collection of scholarly papers of Dniprovsk State Technical University (Technical Sciences) 2, no. 43 (December 25, 2023): 39–55. http://dx.doi.org/10.31319/2519-2884.43.2023.4.
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Attention is drawn to the fact that the issues of effective processing of such fragile, difficult-to-process materials as mono- and polycrystalline diamonds are currently being discussed in the literature, including CVD diamond films, sapphire, etc. For the most part, such processing is faced with the issues of thermal impact on the surface of the tool material, taking into account the defects of the diamonds that undergo processing, directed impact on the surface of such diamonds, heat and modification of the surface of diamonds and accompanying tool materials.
In this review, attention is focused on the newest modern developments, namely 2023, in the features of thermal effects on carbon materials, diamond, and steel. Studies are shown in the direction of directed changes in the surface of diamonds: obtaining the surface of OH-diamonds and H-diamonds, doping diamond, and changing the contact of the diamond surface with Fe and W. Special attention is paid to the application of various protective coatings on the surface of diamonds and related tool materials (steels, ceramics and hard alloys). At the same time, the greatest attention is paid to metal and nitride coatings, that is, this direction has recently become important and relevant.
Various models of doped diamond, places of adsorption of O atoms on its various surfaces, and the subsequent process of the reaction of the O2 molecule with the C atom are considered. The results show that the multi-alloy diamond model has the highest activation energy, which reflects the best properties of oxidation resistance. Research shows that diamond with a rough surface has a larger surface area and higher electronegativity than normal diamond, which improves the adhesion between the Ni-based bond and the diamond with a rough surface.
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Zhang, Qunli, Yiyun Chen, Bo Li, Changyi Wang, Lijuan Wu, and Jianhua Yao. "Tribological Behavior of Ti-Coated Diamond/Copper Composite Coating Fabricated via Supersonic Laser Deposition." Lubricants 11, no. 5 (May 11, 2023): 216. http://dx.doi.org/10.3390/lubricants11050216.
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Diamond/copper composite coating is promising for wear-resistant applications, owing to the extreme hardness of the diamond reinforcement. Ti-coated diamond/copper composite coatings with various laser powers were successfully fabricated employing the novel manufacturing technology of supersonic laser deposition (SLD). Ti-coated diamond, which was able to enhance the wettability between diamond and copper, was prepared at the optimal parameters via salt bath. Nano-spherical titanium carbides were uniformly distributed on the diamond’s surface to generate a favorable interface bonding with a copper matrix though mechanical interlocking and metallurgical bonding during impact. Furthermore, the results showed that the transition layer acted as a buffer, preventing the breakage of the diamond in the coating. SLD can prevent the graphitization of the diamonds in the coating due to its low processing temperature. The coordination of laser and diamond metallization significantly improved the tribological properties of the diamond/copper composite coatings with the SLD technique. The microhardness of the diamond/copper composite coating at a laser power of 1000 W reached about 172.58 HV0.1, which was clearly harder than that of the cold sprayed copper. The wear test illustrated that the diamond/copper composite coating at a laser power of 1000 W exhibited a low friction coefficient of 0.44 and a minimal wear rate of 11.85 μm3·N−1·mm−1. SLD technology shows great potential in the field of preparing wear-resistant hard reinforced phase composite coatings.
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Liu, Fukang, Ying Guo, Shaojie Lv, and Guange Chen. "Application of the Entropy Method and Color Difference Formula to the Evaluation of Round Brilliant Cut Diamond Scintillation." Mathematics 8, no. 9 (September 3, 2020): 1489. http://dx.doi.org/10.3390/math8091489.
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A modeling approach combining the entropy method and color difference formula is proposed in order to quantitatively evaluate diamond scintillation. The images of 66 diamonds were captured from 0° to 105° rotation at 15° intervals. The color difference of corresponding pixels in adjacent rotation angle images was calculated using a MatLab r2014a program, which indicated the diamond’s color change due to its scintillation. A threshold (10) was determined to divide the color difference into seven color difference intervals, the percentage of which indicated the color-change area. The color difference and the percentage were comprehensively analyzed using the entropy method to evaluate diamond scintillation objectively and quantitatively. Lightness was the main factor affecting the diamond scintillation while chroma and hue also significantly affected it.
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Levin, М., and I. Sheveleva. "Institutional Aspects of the International Diamond Market’s Organization and Functioning." Voprosy Ekonomiki, no. 10 (October 20, 2009): 62–79. http://dx.doi.org/10.32609/0042-8736-2009-10-62-79.
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The article analyzes the institutional and structural heterogeneity of international diamond market. Two market levels are considered: diamond primary supply (by mining companies) and the level of rough diamonds resales and polished diamonds manufacturing. It is shown that on the primary diamond market level the oligopoly structure has been established, and the secondary rough diamond market level is competitive. On the primary market level contractual commitments are enforced by "block booking sales"; on the level of rough diamonds resales and polished diamonds manufacturing — by social and ethnic homogeneous groups and networks as well as by reputation.
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KVASNYTSYA, V. M. "The Size and Shape of Diamond Crystals of Different Origin." Mineralogical Journal 44, no. 1 (2022): 32–40. http://dx.doi.org/10.15407/mineraljournal.44.01.032.
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The size and shape of diamond crystals of different origin are analyzed. Diamonds with a size of less than about 0.5 mm are classified as microcrystals. Diamonds found in meteorites typically show non-faceted anhedral crystals of various sizes. Only the Canyon Diablo iron meteorite has cubic microcrystals of unclear crystallogenesis. Nano, micro- and macro-sized crystals of diamond in meteorites are usually aggregate in nature. The release of diamond polyhedra in meteorites is limited by the too small size of its crystals in chondrites and by its solid-phase transformation from very fine-grained diamond and graphite in ureilites and octahedrites. The size and shape of diamond crystals found in meteorite impact craters are determined by the nature of the source carbon material. The process of solid-phase transformation of graphite or other carbon-bearing materials (e.g., coal, plant remains) to diamond in meteorite craters does not allow euhedral crystal to be formed. At the same time, in the case of diamonds formed from impacts, on the (0001) faces of impact apographitic diamonds, polyhedra of nano-microdiamonds crystallize from the gas phase. These crystals are often form autoepitaxially, because they crystallize in an oriented manner on the lonsdaleite -diamond matrix. Diamonds found in metamorphic rocks, ophiolites and modern volcanites show faceted microcrystals. A wide range of sizes, from 0.1 mm to 10 cm, is characteristic of faceted diamond crystals from kimberlites, lamproites and lamprophyres. Diamond crystals from different mantle rocks acquire a multifaceted shape after reaching certain embryo sizes — the most likely appearance of diamond polyhedra larger than 40-50 nm. Octahedra forms are dominant for natural diamond crystals of different sizes and origin.
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Li, Hongdong, Shaoheng Cheng, Jia Li, and Jie Song. "A Review on the Low-Dimensional and Hybridized Nanostructured Diamond Films." Journal of Nanomaterials 2015 (2015): 1–15. http://dx.doi.org/10.1155/2015/692562.
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In the last decade, besides the breakthrough of high-rate growth of chemical vapor deposited single-crystal diamonds, numerous nanostructured diamond films have been rapidly developed in the research fields of the diamond-based sciences and industrial applications. The low-dimensional diamonds of two-dimensional atomic-thick nanofilms and nanostructural diamond on the surface of bulk diamond films have been theoretically and experimentally investigated. In addition, the diamond-related hybrid nanostructures of n-type oxide/p-type diamond and n-type nitride/p-type diamond, having high performance physical and chemical properties, are proposed for further applications. In this review, we first briefly introduce the three categories of diamond nanostructures and then outline the current advances in these topics, including their design, fabrication, characterization, and properties. Finally, we address the remaining challenges in the research field and the future activities.
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Xia, Yue, Yunxiang Lu, Guoyong Yang, Chengke Chen, Xiaojun Hu, Hui Song, Lifen Deng, Yuezhong Wang, Jian Yi, and Bo Wang. "Application of Nano-Crystalline Diamond in Tribology." Materials 16, no. 7 (March 28, 2023): 2710. http://dx.doi.org/10.3390/ma16072710.
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Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and poly-crystalline diamonds, nano-crystalline diamond consists of disordered grains and thus possesses good toughness and self-sharpening. These merits render nano-crystalline diamonds to have great potential in tribology. Moreover, the re-nucleation of nano-crystalline diamond during preparation is beneficial to decreasing surface roughness due to its ultrafine grain size. Nano-crystalline diamond coatings can have a friction coefficient as low as single-crystal diamonds. This article briefly introduces the approaches to preparing nano-crystalline diamond materials and summarizes their applications in the field of tribology. Firstly, nano-crystalline diamond powders can be used as additives in both oil- and water-based lubricants to significantly enhance their anti-wear property. Nano-crystalline diamond coatings can also act as self-lubricating films when they are deposited on different substrates, exhibiting excellent performance in friction reduction and wear resistance. In addition, the research works related to the tribological applications of nano-crystalline diamond composites have also been reviewed in this paper.
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Shi, Zitao, Qilong Yuan, Yuezhong Wang, Kazuhito Nishimura, Guojian Yang, Bingxue Zhang, Nan Jiang, and He Li. "Optical Properties of Bulk Single-Crystal Diamonds at 80–1200 K by Vibrational Spectroscopic Methods." Materials 14, no. 23 (December 3, 2021): 7435. http://dx.doi.org/10.3390/ma14237435.
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Bulk diamonds show great potential for optical applications such as for use in infrared (IR) windows and temperature sensors. The development of optical-grade bulk diamond synthesis techniques has facilitated its extreme applications. Here, two kinds of bulk single-crystal diamonds, a high-pressure and high-temperature (HPHT) diamond and a chemical vapor deposition (CVD) diamond, were evaluated by Raman spectroscopy and Fourier Transform Infra-Red (FTIR) spectroscopy at a range of temperatures from 80 to 1200 K. The results showed that there was no obvious difference between the HPHT diamond and the CVD diamond in terms of XRD and Raman spectroscopy at 300–1200 K. The measured nitrogen content was ~270 and ~0.89 ppm for the HPHT diamond and the CVD diamond, respectively. The moderate nitrogen impurities did not significantly affect the temperature dependence of Raman spectra for temperature-sensing applications. However, the nitrogen impurities greatly influence FTIR spectroscopy and optical transmittance. The CVD diamond showed higher transmittance, up to 71% with only a ~6% drop at temperatures as high as 873 K. This study shows that CVD bulk diamonds can be used for IR windows under harsh environments.
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Neubauer, Erich, G. Kladler, C. Eisenmenger-Sittner, J. Hell, C. Prentice, P. Angerer, and Łukas Ciupiński. "Interface Design in Copper-Diamond Composite by Using PVD and CVD Coated Diamonds." Advanced Materials Research 59 (December 2008): 214–19. http://dx.doi.org/10.4028/www.scientific.net/amr.59.214.
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One of the key problems in copper-diamond composites is the interface between the metal matrix and the diamond reinforcement. In order to take advantage of the high thermal conductive diamond filler in a composite the design of the interface is crucial. One approach to minimize the thermal contact resistance between metal and diamond reinforcement is to coat the diamonds with functional layers, e.g. Mo or W. For coating of diamonds PVD and CVD have been used followed by characterization of coating thickness by different methods. The coated diamonds were used for composite manufacturing and the thermal diffusivity of the compacted materials was measured.
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Tillmann, Wolfgang, and Artur Martin Osmanda. "Production of Diamond Tools by Brazing." Materials Science Forum 502 (December 2005): 425–30. http://dx.doi.org/10.4028/www.scientific.net/msf.502.425.
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Diamond tools are increasingly gaining importance as cutting materials for various construction materials. The quality of synthetic diamonds, monocrystalline as well as polycrystalline or CVD-diamonds has been significantly improved over the last years. Integrating these cutting materials requires adequate joining technologies that produce sound joints without exposing the temperature sensitive diamond to too elevated temperatures. The paper highlights current developments in the joining of synthetic diamonds to steel. Owing to their covalent atomic bonding diamonds cannot easily be wetted and joined by employing conventional brazing alloys. Hence, active agents are needed to foster an interfacial reaction. Different active filler concepts are presented and discussed regarding their joint formation. The brazing temperatures influence not only possible diamond degradation but also the interfacial decomposition of the diamond due to the formation of corresponding reaction layers.
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Varlamova, Liubov A., Sergey V. Erohin, and Pavel B. Sorokin. "The Role of Structural Defects in the Growth of Two-Dimensional Diamond from Graphene." Nanomaterials 12, no. 22 (November 12, 2022): 3983. http://dx.doi.org/10.3390/nano12223983.
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The presented work is devoted to the study of the formation of the thinnest diamond film (diamane). We investigate the initial stages of diamond nucleation in imperfect bilayer graphene exposed by the deposition of H atoms (chemically induced phase transition). We show that defects serve as nucleation centers, their hydrogenation is energy favorable and depends on the defect type. Hydrogenation of vacancies facilitates the binding of graphene layers, but the impact wanes already at the second coordination sphere. Defects influence of 5|7 is lower but promotes diamondization. The grain boundary role is similar but can lead to the final formation of a diamond film consisting of chemically connected grains with different surfaces. Interestingly, even hexagonal and cubic two-dimensional diamonds can coexist together in the same film, which suggests the possibility of obtaining a new two-dimensional polycrystal unexplored before.
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Litvin, Yu A. "Physicogeochemical Mechanisms of the Genesis of Matryoshka-Type Diamonds on the Basis of the Mantle-Carbonatite Theory." Геохимия 68, no. 3 (March 1, 2023): 255–70. http://dx.doi.org/10.31857/s001675252303007x.
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A physicochemical analysis of the genesis of a unique Matryoshka-type diamond from the Nyurbinskaya kimberlite pipe of the Nakyn kimberlite field, Yakutia, Russia, was performed. The specimen consists of a host diamond with a cavity containing a loose diamond inclusion; two through holes with a width of 0.1–0.4 mm emerge from the cavity. The analysis is based on the mantle-carbonatite theory of the genesis of diamonds and associated phases developed on the basis of consistent results of a physicochemical experiment and an analytical study of paragenetic inclusions in natural diamonds from kimberlite deposits. The published data of crystal morphological and physical studies of the Matryoshka diamond were used as well. As a result, the physicogeochemical mechanisms of nucleation and crystallization of the host diamond with a cavity and diamond inclusion under the conditions of mass genesis of diamonds in completely miscible carbonate–eclogite–carbon melts of the upper-mantle diamond-forming chamber are substantiated. The initially closed cavity was filled with a diamond-forming carbonate–silicate melt with dissolved carbon. In addition, an analysis of the conditions of etching and dissolution of the host diamond and diamond inclusion during the kimberlite transport of diamond-bearing material from the mantle chamber to the depths of the Earth’s crust was performed. The reasons for the explosive formation of cone-shaped through holes in the main diamond, which was accompanied by the ejection of the diamond-forming medium and the filling of the cavity with (С–О–Н)-fluid-containing kimberlite melt, are considered. The final episodes of partial dissolution of diamonds from the Matryoshka sample by kimberlite and assimilated melts continued during the formation of a cumulative chamber in the Earth’s crust and its solidification with the release of a highly compressed C–O–H fluid. “Fluid drilling” of the top of the cumulative chamber stimulated the explosive formation of the Nyurbinskaya pipe and its filling with kimberlite and assimilated diamondiferous matter. With prolonged compaction of this substance, the Matryoshka diamond was subjected to atmospheric and hydrothermal factors, as is evidenced by fine-grained sedimentary barite, a mineral of barium sulphate, found in the through holes of the host diamond.
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Zhang, T., Fang Hong Sun, Bin Shen, and Z. M. Zhang. "Fabrication and Characterization of High Quality Micro Diamonds by Hot Filament CVD." Advanced Materials Research 325 (August 2011): 582–87. http://dx.doi.org/10.4028/www.scientific.net/amr.325.582.
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The high quality micro diamonds with the euhedral diamond faces are fabricated by hot filament chemical vapor deposition technique (HFCVD). The high pressure and high temperature (HPHT) single crystal diamonds in size of 1 μm are used as seeds. In order to disperse the diamond seeds uniformly on a silicon wafer, the photoresist solution with diamond seeds are performed on the silicon wafer by a spin coater machine. The high substrate temperature and low acetone concentration are employed for decreasing the nucleation rate and accelerating the growth rate. The morphology and quality of the micro diamonds are observed and analyzed by SEM and Raman spectroscopy. After 4 hours of the deposition, the surface imperfections of the diamond seeds have disappeared completely, and the euhedral diamond faces with (111) and (100) begin to emerge. Subsequently, 8 hours of deposition leads to a final average size of approximately 4 μm. The micro diamonds have very high quality, and the surfaces appear flat and smooth in this stage. The results indicate that it is an effective way to eliminate the defects of the HPHT micro diamonds and develop high quality diamonds with well-defined morphology by HFCVD technique.
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Khachatryan, Galina, and Nataliya Anashkina. "Ratio of structural impurity distribution in diamond crystals and kimberlite pipe diamond potentiak (case study of Arkhangelsk region and Yakutia)." Ores and metals, no. 3 (November 3, 2021): 114–30. http://dx.doi.org/10.47765/0869-5997-2021-10023.
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IR spectroscopy was used to compare diamonds from 12 pipes, Arkhangelsk region. Based on positive correlation between average N and H values in diamonds from various deposits, it was found that crystals from low-grade diamond pipes are relatively enriched in hydrogen compared with diamonds from Lomonosov and Grib deposits. In terms of structural impurity distribution, Arkhangelsk deposit diamonds differ from Yakutian diamonds; it could be due to various composition of compared diamonds’ source matter and thermodynamic conditions of their growth. It is shown that hydrogen is a negative factor of diamond potential in both Yakutian and Arkhangelsk diamonds. This can partly be explained by impuri-ty blocking effect on diamond crystal growth.
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Jotanovic, Vera, and Rita Laura D’Ecclesia. "Do Diamond Stocks Shine Brighter than Diamonds?" Journal of Risk and Financial Management 12, no. 2 (May 3, 2019): 79. http://dx.doi.org/10.3390/jrfm12020079.
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This paper addresses two practical investment questions: Is investing in the diamond equity market a more feasible and liquid alternative to investing in diamonds? Additionally, is diamond equity affected by polished diamond prices? We assemble an original database of diamond mining stock prices traded on main stock exchanges in order to assess their relationship with diamond prices. Our results show that the market of diamond-mining stocks does not represent a valid investment alternative to the diamond commodity. Diamond equity returns are not driven by diamond price dynamics but rather by local market stock indices.
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Yacoot, A., and M. Moore. "X-ray topography of natural tetrahedral diamonds." Mineralogical Magazine 57, no. 387 (June 1993): 223–30. http://dx.doi.org/10.1180/minmag.1993.057.387.04.
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AbstractThe symmetry of diamond is still sometimes questioned. Most people agree that diamond belongs to the space group Fdm and therefore to point group . Some however, on account of the existence of a few natural tetrahedral diamonds, have assigned diamond to the point group 3m. We report here on an X-ray topographic investigation, using both conventional and synchrotron sources, of eleven natural tetrahedral diamonds. Two large specimens (from the Alpheus Williams' collection) were studied and found to consist of two portions, unequal in size, that were twinned on a (111) plane. Another diamond (from Professor R. A. Howie's collection) was found to contain two non-parallel (111) twin planes with the diamond filling the space between them, giving the crystal a tetrahedral morphology. Four tetrahedral diamonds (selected by Tolansky) were shown to be either twinned on a (111) plane, or cleavage fragments consisting of one component of a made or single crystals that had been plastically deformed. Similar results were found for some diamonds from the Argyle Mine. Our findings are consistent with diamond belonging to the holosymmetric class () rather than to the hemihedral class (3m).
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Gao, Chao, Jun Tang Yuan, Hao Jin, and Zhong Quan Song. "Wear Characteristics of Impregnated Diamond Bit in Drilling Armor Ceramic." Advanced Materials Research 179-180 (January 2011): 1150–55. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.1150.
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This paper describes the wear characteristics of impregnated diamond bits when drilling in Al2O3 armor ceramic. With different bits being developed, drilling experiments and scanning electron microscope (SEM) examinations were conducted, and the results show that diamond wear types consist of complete crystal shape, micro fragmentation, whole fragmentation, wearing flat and falling off of diamond; abrasive wear, impact abrasion and erosion exist in the wear of diamond and bond; diamond grain size and concentration have their optimal value under fixed machining conditions; diamonds of high quality could increase bit drilling efficiency and serving life; the bit whose abrasion rate of bond matches that of diamonds presents the best comprehensive properties.
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Zhan, You Ji, Yuan Li, Hui Huang, and Xi Peng Xu. "Wear of Brazed Diamond Wheel in Grinding of Cemented Carbide." Key Engineering Materials 416 (September 2009): 198–204. http://dx.doi.org/10.4028/www.scientific.net/kem.416.198.
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Grinding forces, protrusion height, grinding temperatures and wear of diamond grits have been studied in grinding cemented carbide YG8 with a single-layer vacuum brazed diamond wheel. The experiment results indicate that the primary wear progression of diamond grits in the whole grinding process follows the mode of whole diamonds, flat diamonds when grinding of the cemented carbide. The worn mechanism of the failure of diamond grits was discussed and possible solutions are recommended. The proportions of diamond conditions and the mean protrusion height of grains are more closely related to grinding forces and grinding temperatures. The grinding forces, force ratio and grinding temperatures decreased with the increasing proportions of whole crystal and the decreasing mean protrusion height of diamond grits, and the tangential and normal force components increased with the gradual wear of the brazed diamond wheel during a long-time grinding process. It shows great potential in improving thermal damage of cemented carbides by reduces grinding temperature with vacuum brazing diamond wheels.
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OuYang, Zhe. "Research on the Diamond Price Prediction based on Linear Regression, Decision Tree and Random Forest." Highlights in Business, Economics and Management 24 (January 22, 2024): 248–57. http://dx.doi.org/10.54097/13ccwv59.
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Diamonds are the symbol of the pure and indestructible love and the luxury that people have always sought after. However, because people know less about diamonds, they often only rely on the introduction of salespeople and jewelers in diamond trading. Therefore, it is difficult for consumers to buy diamonds of equal value and price. To solve this problem, this paper uses Multiple Linear Regression model, Decision Tree Regression model and Random Forest Regression model to predict diamond prices based on various diamond evaluation metrics in data set, so that consumers can intuitively learn about the normal price of the evaluation metrics of selected diamonds. Through this paper, it is found that the Random Forest Regression model has the best fitting and predictive ability in diamond prediction task, which is also the most recommended model.
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Zhang, Xuliang, Youhong Sun, Qingnan Meng, Jinhao Wu, and Linkai He. "Enhancement of Oxidation Resistance via Chromium Boron Carbide on Diamond Particles." Coatings 11, no. 2 (January 30, 2021): 162. http://dx.doi.org/10.3390/coatings11020162.
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To improve the oxidation resistance of diamond, chromium boron carbide (Cr–B–C) coatings were synthesized through high temperature solid state synthesis and molten salt method on diamond particles in this paper. After holding the raw material at 900 °C for 2 h, the diamond surface was completely and uniformly covered by Cr–B–C coatings. Oxidation resistance of the diamond coated Cr–B–C was determined by the thermogravimetric analysis (TGA). The results revealed that the Cr–B–C coatings held the diamonds for 100%-mass in air atmosphere until 1151 °C, which was much better than the uncoated diamonds (720 °C) and the B4C-coated diamonds (1090 °C). When Cr–B–C-coated diamond was annealed in air, Cr2O3 and B2O3 were formed as oxygen barrier layer to protect diamond from oxidation. The formation of B2O3 with high temperature fluidity was conducive to avoiding Cr2O3 delamination due to volume expansion during oxidation in air. Furthermore, the presence of Cr2O3 provided lasting protection by reducing the evaporation of B2O3. The oxidation products (B2O3 and Cr2O3) prove a complementary functional protection on diamond particles from oxidation.
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Pokhilenko, Lyudmila, Nikolay Pokhilenko, Vladimir Malkovets, and Taisia Alifirova. "The Earliest Generation of Diamond: The First Find of a Diamond Inclusion in Kimberlitic Olivine." Minerals 13, no. 1 (December 26, 2022): 36. http://dx.doi.org/10.3390/min13010036.
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Today, it is known that the majority of diamonds are crystallized mostly from a metasomatic agent close in the main characteristics to carbonatite melts acting upon mantle rocks, and therefore, diamonds are located in the interstitial space of these rocks. So far, diamond has never been found included in other kimberlitic or xenolithic minerals. We have found a diamond inclusion inside the kimberlitic olivine grain, which is the first find of its kind. The diamond crystal is to have been captured by the growing olivine at quite high temperatures (more than 1400 °C) early in the history of the cratonic lithospheric mantle formation. The event had taken place long before the depleted peridotite cooled down to the temperature of the Middle Archean cratonic geotherm corresponding to the diamond stability field at depths where carbonatite melts can react with depleted peridotite, making it a diamond-bearing rock. On the one hand, this find provides evidence that diamonds can crystallize from the high-temperature silicate melt with some carbonate component. On the other hand, the diamond was found coexisting with a sulfide inclusion in the same olivine, i.e., crystallization from a sulfide melt may be another way of diamond formation.
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Liao, Yunn Shiuan, and C. T. Yang. "Investigation of the Wear of the Pad Conditioner in Chemical Mechanical Polishing Process." Advanced Materials Research 76-78 (June 2009): 195–200. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.195.
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The pad surface will become grazed because of the accumulated debris in the chemical mechanical polishing (CMP) process. It results in the reduction of the wafer removal rate, and a pad conditioner or diamond disk must be frequently employed to refresh the pad surface. The wear behavior of a diamond with respect to its location, original relative protruded height and protruded shape on a diamond disk was investigated in this thesis. It was found from experimental data that the diamonds which were located outside, originally protruded more highly and with crest lines oriented upward wore faster. Accordingly, four suggestions were proposed to obtain the uniform diamond wear. They are: lowering the protruded heights of the outside diamonds, replacing the current flat substrate by a curved surface substrate, changing the diamond distribution on the disk from the current uniform one to a higher concentration around outside diameter, and orienting the diamonds such that the flats are protruded upward for the outside diamonds and the crest lines are projected upward for the inside diamonds. Experiment had verified that the pad conditioner with center-protruded substrate led to a stable and higher dressing rate.
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Craven, J. A., B. Harte, D. Fisher, and D. J. Schulze. "Diffusion in diamond. I. Carbon isotope mapping of natural diamond." Mineralogical Magazine 73, no. 2 (April 2009): 193–200. http://dx.doi.org/10.1180/minmag.2009.073.2.193.
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AbstractRecent advances in ion microprobe instrumentation and techniques have enabled the mapping of C isotope ratios across the whole of a polished plate of a natural diamond from Guaniamo, Venezuela. The resultant map of C isotope variation closely matches the cathodoluminescence image of the growth structure of the diamond and, therefore, indicates an extremely limited scale of diffusion of C atoms sincethetimeof diamond formation. This result is compatible with thelimite d mobility of N atoms shown by theIaAB aggregation stateof thediamond. Inclusions in thediamond aree clogitic, in common with many Guaniamo diamonds with temperatures of formation of around 1200ºC. At such temperature the IaAB aggregation state indicates a mantle residence time on the order of 1 Ga. Such temperatures of formation and mantle residence times are common to many natural diamonds; thus the extremely limited diffusion of C isotopes shown by the mapping indicates that many diamonds will retain the C isotope compositions of their initial formation.
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Chen, Yongqian, Shanghua Zhang, Jialin Liu, Wei Zhang, Qingyuan Ma, Xiwang Wu, Shirui Guo, et al. "Numerical Simulation of Temperature Characteristics and Graphitization Mechanism of Diamond in Laser Powder Bed Fusion." Materials 16, no. 18 (September 21, 2023): 6338. http://dx.doi.org/10.3390/ma16186338.
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Thermal damage to diamonds is a major limitation in laser powder bed fusion (LPBF) processing of metal matrix diamond composites. In this paper, a numerical simulation model was established to describe the thermal effect of the Diamond-CuSn10 composite on the LPBF process. The simulation results show that the temperature of the diamond presents a double-peak structure, and the double-peak temperature curve shape can be modulated by modifying the laser scanning offset and the size of the diamond powder. And it suggests that the heat of the diamond mainly comes from the transfer of the molten pool. Then, combined with the experimental phenomenon, the mechanism of diamond graphitization in the LPBF process is analyzed. It indicates that since the surface defects of the diamond inhibit the heat conduction of the diamond, the temperature accumulates on the surface, leading to the graphitization of the diamond. Finally, based on this model, the potential of Ti-coated diamonds to prevent and reduce thermal damage in the LPBF process has been extensively studied. It is found that a Ti coating with low thermal conductivity can effectively reduce diamond temperature and improve diamond graphitization resistance. This study can provide a good method and basis for the preliminary selection of LPBF process parameters and the understanding of the graphitization mechanism of diamond tools.
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Chepurov, Anatoly, Sergey Goryainov, Sergey Gromilov, Egor Zhimulev, Valeriy Sonin, Aleksey Chepurov, Zakhar Karpovich, Valentin Afanasiev, and Nikolay Pokhilenko. "HPHT-Treated Impact Diamonds from the Popigai Crater (Siberian Craton): XRD and Raman Spectroscopy Evidence." Minerals 13, no. 2 (January 20, 2023): 154. http://dx.doi.org/10.3390/min13020154.
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Phase change and graphitization of diamonds from the Popigai impact crater (Krasnoyarsk Territory, Siberian platform, Russia) exposed to high-pressure high-temperature (HPHT) conditions of 5.5 GPa and 2000–2200 °C are studied by Raman spectroscopy and X-ray diffractometry (XRD). Light-color diamonds of type 1, free from inclusions, with 0 to 10 % lonsdaleite, are more resistant to HPHT effects than dark diamonds of type 2 rich in lonsdaleite and graphite. The lonsdaleite/diamond ratios in lonsdaleite-bearing impact diamonds become smaller upon annealing, possibly because lonsdaleite transforms to cubic diamond simultaneously with graphitization. Therefore, lonsdaleite is more likely a structure defect in diamond than a separate hexagonal phase.
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CHEN, CHANGLE, and QIANWANG CHEN. "RECENT DEVELOPMENT IN DIAMOND SYNTHESIS." International Journal of Modern Physics B 22, no. 04 (February 10, 2008): 309–26. http://dx.doi.org/10.1142/s0217979208038685.
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The high pressure-high temperature (HPHT) method led to wide applications of artificial diamonds in industry. Low temperature coating of diamonds has been studied for some time, and chemical vapor deposition has been developed. In this contribution, we will focus on the most recent developments in diamond synthesis, and especially the important progress upon hydrothermal synthesis and the reduction of carbide (HSRC), which has attracted more and more attention due to its great commercial potential. Especially, we will discuss the synthesis of colorless, large diamond crystals from the reduction of carbon dioxide or carbonates. In addition, some recent progress on the theoretical studies of the metastable nucleation and growth of diamonds will also be reviewed. Finally, theories about the genesis of natural diamond were briefly reviewed, and a new theory based on our experimental results was proposed, which suggests that diamond within the Earth could be produced from carbon dioxide wherever carbon dioxide existed and the conditions (e.g., temperature, pressure, and reducing environment) are satisfied.
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Yang, Jun De, Wen Li Lin, and Yuan Wang. "Research on the Design of Diamond Size in Diamond Drill Bits and Diamond Saw Blades." Applied Mechanics and Materials 148-149 (December 2011): 1548–53. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1548.
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In this paper, it is assumed that diamond’s cross-section is hexagonal, which is similar to the actual condition. At first the diamond cutting depth of diamond drill bits and diamond saw blades has been calculated and analyzed. A variety of diamond size and diamond exposure difference has also been calculated and analyzed. It is shown that the cutting depth of single diamond was generally below 0.02mm and the difference on diamond exposure between coarse and fine diamond must be less than diamond cutting depth to achieve efficient rock breaking. Some diamond size design methods are acquired via the calculations and analysis.
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Kaminsky, F. V., and S. A. Voropaev. "Modern Concepts on Diamond Genesis." Geochemistry International 59, no. 11 (November 2021): 1038–51. http://dx.doi.org/10.1134/s0016702921110033.
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AbstractThe best-known, most well-studied diamondiferous rocks are kimberlites and lamproites. Diamonds are also found in impactites, metamorphic rocks, ophiolites, and modern volcanic rocks. Diamonds from these rocks differ from kimberlitic diamonds in size, morphology, trace-element and isotope composition, and physical properties. Differences in these characteristics are related to their different mechanisms of origin. In some cases, diamonds can be formed in “metastable” conditions under disequilibrium thermodynamic parameters, supporting the conclusion that diamond is a polygenetic mineral, formed in nature under different physicochemical and geodynamic conditions. According to thermodynamic considerations and calculations, “metastable” crystallization of diamond is mainly controlled by the size of the forming crystallites. The main effectors in decreasing the energetic barrier for nanosized diamonds are surface tension and related surface energy.
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Ekgasit, Sanong, and Pimthong Thongnopkun. "Transflectance Spectra of Faceted Diamonds Acquired by Infrared Microscopy." Applied Spectroscopy 59, no. 9 (September 2005): 1160–65. http://dx.doi.org/10.1366/0003702055012555.
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A novel transflectance technique using an infrared microscope was employed for spectral acquisition of loose and mounted faceted diamonds. The observed transflectance spectrum shows the same spectral features as those of the well-accepted diffuse reflectance spectrum. Unlike the diffuse reflectance spectrum, the transflectance spectrum was not affected by the diamond arrangements. The technique can be employed for direct spectra acquisition of mounted diamonds without taking the diamonds out of the jewelry bodies. Moreover, an individual diamond on a complex jewelry setting can be selectively measured. Infrared absorption bands unique to the chemical compositions, impurities, and treatment processes of the diamonds are discussed. The observed transflectance spectra can be exploited for diamond classification.
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Zinchuk, Nikolay, and Leonid Bardukhinov. "Diamond study features in forecasting and prospecting (Siberian platform)." Ores and metals, no. 3 (November 3, 2021): 59–75. http://dx.doi.org/10.47765/0869-5997-2021-100018.
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Based on the completed research and data summary on diamonds specific features (an example from the Siberian platform), conclusions were made that indications exist at all levels of their location: from kimberlite-related provinces, subprovinces, fields, diatremes to ore shoots. Population of diamond varieties in kimberlite rocks forms parasteric, rather than paragenetic, associations related to their coexistence in kimberlites. Morphological criteria of kimberlite diamond potential were defined depending on rounded diamonds content in them. Significant differences in kimberlites diamond potential were not revealed to the explored depth of diatremes. A conclusion about the absence of horizontal concentric zonality in the change of diamond typomorphic features was made.
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Zinchuk, Nikolay, and Leonid Bardukhinov. "Diamond study features in forecasting and prospecting (Siberian platform)." Ores and metals, no. 3 (November 3, 2021): 59–75. http://dx.doi.org/10.47765/0869-5997-2021-10018.
Full textAbstract:
Based on the completed research and data summary on diamonds specific features (an example from the Siberian platform), conclusions were made that indications exist at all levels of their location: from kimberlite-related provinces, subprovinces, fields, diatremes to ore shoots. Population of diamond varieties in kimberlite rocks forms parasteric, rather than paragenetic, associations related to their coexistence in kimberlites. Morphological criteria of kimberlite diamond potential were defined depending on rounded diamonds content in them. Significant differences in kimberlites diamond potential were not revealed to the explored depth of diatremes. A conclusion about the absence of horizontal concentric zonality in the change of diamond typomorphic features was made.
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Bulgakova, Vladislava, Pavel Chizhov, Alexander Ushakov, Pavel Ratnikov, Yuri Goncharov, Artem Martyanov, Vitali Kononenko, et al. "Optical Pump–Terahertz Probe Diagnostics of the Carrier Dynamics in Diamonds." Materials 17, no. 1 (December 26, 2023): 119. http://dx.doi.org/10.3390/ma17010119.
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Diamond is a promising material for terahertz applications. In this work, we use a non-invasive optical pump–terahertz probe method to experimentally study the photoinduced carrier dynamics in doped diamond monocrystals and a new diamond-silicon composite. The chemical vapor deposited diamond substrate with embedded silicon microparticles showed two photoinduced carrier lifetimes (short lifetime on the order of 4 ps and long lifetime on the order of 200 ps). The short lifetime is several times less than in boron-doped diamonds and nitrogen-doped diamonds which were grown using a high temperature–high pressure technique. The observed phenomenon is explained by the transport of photoexcited carriers across the silicon–diamond interface, resulting in dual relaxation dynamics. The observed phenomenon could be used for ultrafast flexible terahertz modulation.
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Hua, Li. "Nano-Crystalline Diamond Development and Application." Advanced Materials Research 476-478 (February 2012): 1500–1503. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1500.
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diamonds have superior performance unmatched by other materials. The nano-crystalline diamond (nano-crystalline diamond powder and nano-crystalline diamond films) is a new construction material and functional material with diamond excellent properties and nano material characteristics. Such dual bizarre characteristics determine its wide application. The application developed predicts its sound prospects, which, however, requires researchers to conduct studies and development.
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Xiang, Dong, Li Qun Jia, and Ke Gao Liu. "Structure and Performance of Chemical Duplex Plating Ti Metal Layer on Diamond Surface by Hydrothermal Method." Advanced Materials Research 936 (June 2014): 1676–80. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1676.
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As a surface of diamond has a higher interfacial energy and worse binding force, the diamond shed from matrix easily. For solving this, the microstructures and properties of the metallic coating on diamond surface were studied. The different temperatures, such as 110, 120, and 130 °C for 6 h, were used for coating diamond in the high-pressure reactor respectively. The structure and performance of the metallic coating on diamond surface were tested by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and diamond compressive strength instrument. The results showed that a continuous and compact coating of Ni, W and Ti on the diamond surface is obtained by the hydrothermal coating technology (chemical duplex plating) at 120 °C. After heat treatment at 850 °C for 1 h, the better layer coatings form for protecting diamonds and reducing the trend of oxidize. Because the carbides of W and Ti present at the boundries between the coating and diamond surface, the combination of chemistry and metallurgy is gotten. The compress strength of diamonds after hydrothermal and heat treatment is higher than that of uncoated particles (those are 54.40% and 85.48%, respectively).
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Alqahtani, Abdulaziz S., Abdulaziz A. AlHelal, Abdullah S. Alayad, Ahmed S. Alotaibi, Fahad A. Alfarraj, Omar S. Alosaimi, and Ziyad H. Alharbi. "Assessment of Diamond Rotary Instruments Advertised for Cutting 3Y-TZP Restorations. A Scanning Electron Microscope Analysis." Journal of Biomaterials and Tissue Engineering 13, no. 3 (March 1, 2023): 493–97. http://dx.doi.org/10.1166/jbt.2023.3274.
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Aim: To examine the cutting efficiency and amount of material removed from crown-cutting diamond burs from a different manufacturer on zirconia using an electric handpiece. Material and Methods: The performance of super coarse diamond bur round-end from five different manufacturers that were commercially advertised as zirconium crown cutters were assessed. The five manufacturers and their respective diamond bur models tested were super coarse Group 1: Dimond bur, Group 2: Zirconia Diamond Bur, Round End Cylinder, Meisinger, Group 3: 4ZR Zirconia Cutter Diamond Crown Removal Bur, Group 4: Brasseler Dental Diamond Bur, Group 5: Expanded SS White® Lineup of Zirconia Cutting Diamonds. The qualitative assessment of diamond burs (before zirconia cutting) and (after zirconia cutting) was assessed using a scanning electron microscope. The mean cutting distance and material removed for each group were calculated and analyzed using one-way ANOVA. Results: The highest cutting efficiency was found in group 2 and the lowest efficiency was observed in group 5. Post-SEM images of rotary zirconia cutting instruments in groups (Post G1-G5) demonstrate pullout, wear, chipping, and loss of the diamond grains in general. Conclusion: Zirconia Diamond Bur (G2) was found to be suitable. Whereas, (G5) Expanded SS White® Lineup of Zirconia Cutting Great White®Z Diamonds is less effective.
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Salikhov, Ravil, Konstantin Garanin, Alexander Tolstov, Oleg Kovalchuk, Victor Garanin, Vitaly Polyanichko, and Anna Nikiforova. "Geology and mineral composition of Zarya kimberlite pipe, western Yakutia." Domestic geology, no. 6 (January 22, 2021): 48–67. http://dx.doi.org/10.47765/0869-7175-2020-10030.
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The geological and tectonic settings of new primary low-grade diamond deposit, the Zarya pipe (Alakit-Markhinsky kimberlite field, Yakutian diamond province, Western Yakutia, Russia), are discussed. Data on the geological structure of the diatreme, mineral composition and kimberlite diamond content is presented. The factors determining the vertical and lateral heterogeneity of the mineral-indicative characteristics of kimberlites, diamond assemblage minerals, and diamonds are considered. It is concluded that diamond quality and grades increase with depth.
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Edtmaier, Christian, Ernst Bauer, Zeze Serge Tako, and Jakob Segl. "Thermal Conductivity Behaviour of Al/Diamond and Ag/Diamond Composites in the Temperature Range 4 K < T < 293 K." Materials Science Forum 825-826 (July 2015): 197–204. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.197.
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Two different systems, the non-reactive Ag–diamond and the reactive Al–diamond system, were assessed by their thermal conductivity behaviour, both were fabricated by gas pressure assisted infiltration of densely packed diamond bulks with aluminium or silver and different Si-concentration and diamonds of varying particle sizes. The effect of Si-concentration on the interface thermal conductance h between Al, Ag and diamonds was investigated in dependence of temperature by measuring thermal conductivity of composites with different sized diamond particles in the temperature range from 4 K up to ambient. Composite thermal conductivities κc(T) can be as high as 860 W m-1 K-1 at roughly 100 K for Al/diamond and 1100 W m-1 K-1 for Ag–Si/diamond at approx. 150 K. Although the Si concentration in the matrix plays an eminent role for κc(T), i.e. the lower the Si concentration, the higher κc(T), interface thermal conductance is almost unaffected in the reactive Al-diamond system. Furthermore, they are close to values determined on clean model systems, i.e. sputtered and evaporated metal layers on diamond monocrystals. For Ag–diamond composites, the matrix composition of Ag–1Si seems to reflect an optimal composition, as the highest thermal conductivity κc(T) and an extraordinary higher interface conductance was achieved compared to Ag–3Si/diamond composites.
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Kvasnytsya, V. M. "A COMPARATIVE ANALYSIS OF DIAMONDS IN NON-KIMBERLITIC ROCKS OF THE WORLD AND NEOGENE SANDS OF UKRAINE." Mineralogical Journal 45, no. 1 (2023): 95–109. http://dx.doi.org/10.15407/mineraljournal.45.01.095.
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The diamond mineralogy from a number of different non-kimberlitic occurrences of the world was analyzed and a comparison to diamonds from Neogene placers of Ukraine was made. Diamonds from lamprophyres of the Canadian Shield, metakomatiites of the Guiana and West African Shields, and ultra-metamorphic rocks in Asian, European and African continental occurrences were considered. In general, Ukrainian Neogene placer diamonds have many similar mineralogical features to diamonds from lamprophyres and metakomatiites, which differ little from diamonds from kimberlites and lamproites. Ukrainian placer diamonds are characterized by their micron sizes (≤0.5 mm), many of them are colored and have a cubic habit and nitrogen-free compositions, relatively frequent spectral Ib and Iаb types, and orange photoluminescence behavior. In addition, many diamonds are characterized by a relatively high content of hydrocarbons (i.e., CH2, CH3 groups and bonds >C=CH2), OH groups, also C=O, N-H, CO3, NO3-groups. This is evidence for a volatile-rich environment during the diamond crystallization. The formation of diamonds from lamprophyres and metakomatiites, as well as from kimberlites and lamproites, occurred under mantle temperatures and pressures. The relatively recently discovered diamond-bearing lamprophyres and metakomatiites have a number of similarities. They are: i) both formed on the edges of Archean cratonic structures, ii) their old ages (2.7 billion years ago and 1.83 billion years ago for the lamprophyres and 2.2 billion years ago for the metakomatiites), iii) both are strongly metamorphosed, iv) both contain many fragments of rocks of various origins, v) both contain rare xenograins of mantle minerals having diamond-bearing peridotite and eclogite associations, and vi) the diamonds themselves are often microcrystals and many are colored and have a cubic habit. The main difference between diamonds from the lamprophyres and metakomatiites is in their carbon isotopic signatures and their thermal history in the mantle. This is expressed by their different nitrogen contents and the different degree of its aggregation. Diamond-bearing ultrametamorphic rocks are mainly Paleozoic-Mesozoic in age (i.e., 531-92 million years) and occupy a tectonic setting at convergent plate boundaries unlike diamond-bearing lamprophyres and metakomatiites. Diamonds from ultrametamorphic rocks differ from diamonds from lamprophyres and metakomatiites as well as from Ukrainian placer diamonds from Neogene sands in a number of ways.
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Kjarsgaard, Bruce A., Nicole Januszczak, and Johann Stiefenhofer. "Diamond Exploration and Resource Evaluation of Kimberlites." Elements 15, no. 6 (December 1, 2019): 411–16. http://dx.doi.org/10.2138/gselements.15.6.411.
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Kimberlites are the main source of natural gem-quality diamonds. The intrepid diamond explorer faces three major problems. First, finding a small, usually less than 300 m diameter, kimberlite, which is often highly weathered. Second, evaluating the quantity of diamonds within a kimberlite that often consists of multiple phases of intrusive and extrusive kimberlite, each with potentially different diamond grades. Third, evaluating the rough diamonds, the value of which is dependent on carat-weight, shape, colour, and clarity. Modern advances in mantle petrology, geophysics, geochemistry, geomorphology, and geostatistics now complement historical exploration knowledge and aid in selecting prospective target areas, resource estimation, and evaluating kimberlite-hosted diamond deposits.
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Kedrova, T. V., I. N. Bogush, N. N. Zinchuk, L. D. Bardukhinov, A. N. Lipashova, and V. P. Saltykova. "Diamond Placers of the Nakyn Kimberlite Field." Russian Geology and Geophysics 63, no. 3 (March 1, 2022): 245–54. http://dx.doi.org/10.2113/rgg20204259.
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Abstract The paper presents the results of studies of diamonds from Early Jurassic sediments making up the Nyurbinskoe buried placer of the Nakyn kimberlite field, unique in diamond reserves. The main task is to identify diamond distribution patterns in the deposits of the Dyakhtar Stratum (lower deposit) and the Ukugut Suite (upper deposit) within the placer. A comparative analysis of the typomorphic features of diamonds from the upper and lower deposits of the placer was carried out. Variations in the contents of crystals with certain properties that form the image of a diamond-bearing geologic object have been revealed. The zonal distribution of diamonds by characteristics in sedimentary deposits, regardless of their age, has been established. The properties of diamonds and their associations change within the placer, which is due to their redeposition during the Early Jurassic sedimentation.
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Sutherland, Donald G. "The diamond deposits of the Mandala basin, SE Guinea, West Africa." Transactions of the Royal Society of Edinburgh: Earth Sciences 84, no. 2 (1993): 137–49. http://dx.doi.org/10.1017/s026359330000345x.
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AbstractThe Mandala drainage basin lies in the central part of the West African craton immediately to the south of the regional watershed. There has been frequent kimberlite dyke intrusion in the basin. The kimberlites range in grade from apparently barren to having a high diamond content. The presence of other undiscovered kimberlites can be inferred from the distribution, chemistry and abundance of kimberlite satellite minerals and variations in diamond size and character. Secondary diamond deposits are widespread with the main concentrations in the present and former Mandala valley bottoms. Tributaries have lower diamond contents. There are systematic variations in the alluvial diamond characteristics which can be explained in terms of diamond sources as well as transport of the diamonds away from those sources. The occurrence of the secondary diamond deposits is explained by the form and distribution of the primary sources, the nature of the drainage network and the long-term evolution of the drainage basin. Since the Pliocene or Early Pleistocene the Mandala has been rejuvenated with incision of the main channel by up to 26 m. This incision has led to flushing of the tributaries and storage of sediment, including diamonds, in the principal channel.