Journal articles: 'Diamond formation'

1

Simakov, Sergey, and Yuri Stegnitskiy. "On the presence of the postmagmatic stage of diamond formation in kimberlites." Записки Горного института 255 (July 26, 2022): 319–26. http://dx.doi.org/10.31897/pmi.2022.22.

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On nowadays multiphase and the facies heterogeneity of the formations are distinguished at the study of kimberlite pipes. Most researchers associate the formation of diamonds only with the mantle source. To date, satellite minerals with specific compositions associated with kimberlite diamonds have been identified as deep mantle diamond association. They are extracted from the concentrate of the kimberlites heavy fraction and may reflect the diamond grade of the pipe. For some minerals in the diamond association, however, they can not be reliable. Some researchers also revealed shallow diamond associations, related to the formation of serpentine, calcite, apatite, and phlogopite. There is recent data on the formation of diamonds in rocks of the oceanic crust. In the last years microdiamonds were identified in chromites of the oceanic crust in association with antigorite formed at 350-650 °C and 0.1-1.6 GPa. As a result, the authors established a postmagmatic kimberlitic stage of diamond formation associated with secondary mineral associations based on the experimental and mineralogical data for the conditions of the shallow upper mantle and crust. Mineralogical and petrographic studies of Angolan kimberlite pipe show that antigorite is the indicator mineral of this stage.

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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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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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Faccincani, Luca, Valerio Cerantola, Fabrizio Nestola, Paolo Nimis, Luca Ziberna, Leonardo Pasqualetto, Aleksandr I. Chumakov, Jeffrey W. Harris, and Massimo Coltorti. "Relatively oxidized conditions for diamond formation at Udachnaya (Siberia)." European Journal of Mineralogy 34, no. 6 (November 15, 2022): 549–61. http://dx.doi.org/10.5194/ejm-34-549-2022.

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Abstract. Thanks to the physical strength of diamonds and their relatively unreactive chemical nature, their mineral inclusions may remain exceptionally preserved from alteration processes and chemical exchanges with surrounding minerals, fluids and/or melts following diamond formation. Cr-bearing spinels are relatively common inclusions found in peridotitic diamonds and important oxybarometers providing information about the oxygen fugacity (fO2) of their source mantle rocks. Here, we investigated a magnesiochromite–olivine touching pair in a diamond from the Udachnaya kimberlite (Siberia) by in situ single-crystal X-ray diffraction and energy-domain synchrotron Mössbauer spectroscopy, aiming to constrain the physical–chemical conditions of diamond formation and to explore the redox state of this portion of the Siberian craton when the diamond was formed. The P–T–fO2 entrapment conditions of the inclusion pair, determined by thermo- and oxybarometric analyses, are ∼ 5.7(0.4) GPa and ∼ 1015(50) ∘C (although entrapment at higher T and re-equilibration during subsequent mantle storage are also possible) and fO2 near the enstatite–magnesite–olivine–diamond (EMOD) buffer. The determined fO2 is similar to, or slightly more oxidized than, those of xenoliths from Udachnaya, but whilst the xenoliths last equilibrated with the surrounding mantle just prior to their entrainment in the kimberlite at ∼ 360 Ma, the last equilibration of the inclusion pair is much older, occurring at 3.5–3.1, ∼ 2 or ∼ 1.8 Ga before final encapsulation in its host diamond. Hence, the similarity between xenoliths and inclusion fO2 values indicates that the modern redox state of this portion of the Siberian lithosphere was likely attained relatively early after its formation and may have persisted for billions of years after diamond formation, at least at the local scale. Moreover, the oxygen fugacity determination for the inclusion pair provides direct evidence of diamond formation near the EMOD buffer and is consistent with recent models suggesting relatively oxidized, water-rich CHO fluids as the most likely parents for lithospheric diamonds.

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Chen, Ming, Jinfu Shu, Xiande Xie, Dayong Tan, and Ho-kwang Mao. "Natural diamond formation by self-redox of ferromagnesian carbonate." Proceedings of the National Academy of Sciences 115, no. 11 (February 26, 2018): 2676–80. http://dx.doi.org/10.1073/pnas.1720619115.

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Formation of natural diamonds requires the reduction of carbon to its bare elemental form, and pressures (P) greater than 5 GPa to cross the graphite–diamond transition boundary. In a study of shocked ferromagnesian carbonate at the Xiuyan impact crater, we found that the impact pressure–temperature (P-T) of 25–45 GPa and 800–900 °C were sufficient to decompose ankerite Ca(Fe2+,Mg)(CO3)2 to form diamond in the absence of another reductant. The carbonate self-reduced to diamond by concurrent oxidation of Fe2+ to Fe3+ to form a high-P polymorph of magnesioferrite, MgFe3+2O4. Discovery of the subsolidus carbonate self-reduction mechanism indicates that diamonds could be ubiquitously present as a dominant host for carbon in the Earth’s lower mantle.

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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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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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LIKHACHEV, Alexander. "Thermohydraulic effect as a possible reason for natural diamonds formation and its manifestation conditions." Domestic geology, no. 6 (January 28, 2022): 100–111. http://dx.doi.org/10.47765/0869-7175-2021-10034.

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It is shown that diamond formation can be associated with the manifestation of the thermohydraulic effect, the explosive water reaction to the impulse action of ultrahigh temperatures (kimberlite magmas). The process simultaneously destroys the “old” diamonds and creates the “new” ones, with possible synthesis and preservation of idiomorphic diamond crystals. The issues of the process occurrence in natural conditions are considered. The general pattern in diamond deposits distribution is noted, which is their preferable confinement to non-magnetic and weakly magnetic fields of the Earth’s crust; these fields are characterized by a reducing environment favorable for diamonds and other minerals formation.

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9

Sobolev, V. V., O. S. Kovrov, M. M. Nalisko, N. V. Bilan, and O. A. Tereshkova. "Compound physical and mechanical effects stimulating metastable diamond formation." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 4 (2021): 47–55. http://dx.doi.org/10.33271/nvngu/2021-4/047.

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Purpose. To synthesize diamond polycrystals in a thermodynamically stable region, and to grow up a single crystal shell under conditions of thermodynamic metastability. To investigate some physical properties and features of the internal structure for synthesized single crystals for the development of new models and hypotheses regarding the issue of diamond genesis. Methodology. Experimental studies using shock-wave effects on a metal alloy containing non-diamond carbon. Methods of infrared and ultraviolet spectroscopy, X-ray phase analysis, electron paramagnetic resonance, isotope analysis, differential thermal analysis, electron microscopy, and others are used. The synthesis of nanocrystalline diamond particles as nuclei for growing single crystals is carried out by the shock-wave method using profiled shock waves. Findings. A complex of physicochemical methods for studying the grown diamond monocrystals has been carried out. The reasons for the discrete growth of diamond and the retention of the central inclusion (a polycrystalline diamond of shock-wave origin) in the process of growth have been established and analyzed. It is shown that the discreteness of diamond formation is characteristic only for thermodynamically metastable conditions. The results of the experiments give grounds to make an assumption about the metastable growth, including of diamonds from primary deposits. Originality. The hypothesis has been developed concerning the origin of diamond nanoparticles in interstellar carbon clouds which refer exclusively to central polycrystalline inclusions in a monocrystal diamond shell. The hypothesis eliminates the scientific contradiction that arises in all cases when attempts are made to interpret the natural discreteness of diamond formation based on the regularities of the graphite-diamond state diagram. Possible causes of discrete diamond formation in nature and the scenario of the formation of diamond nanocrystals in an interstellar cloud of atomic carbon have been considered. Practical value. The value of the experimental research results refers to the development of a non-energy-intensive technology for the growing large diamond monocrystals at temperatures of 5001400 K, and pressures of 105107 Pa.

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10

Logvinova, Alla M., Richard Wirth, Ekaterina N. Fedorova, and Nikolai V. Sobolev. "Nanometre-sized mineral and fluid inclusions in cloudy Siberian diamonds: new insights on diamond formation." European Journal of Mineralogy 20, no. 3 (May 29, 2008): 317–31. http://dx.doi.org/10.1127/0935-1221/2008/0020-1815.

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11

Karpovich, Z. A., and E. I. Zhimulev. "Experimental Modeling of Diamond Formation Processes in Fe-C-S System at High P-T Parameters." Bulletin of Irkutsk State University. Series Earth Sciences 34 (2020): 67–81. http://dx.doi.org/10.26516/2073-3402.2020.34.67.

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The problem of diamond formation, despite the huge amount of accumulated information, has not been finally resolved. Currently, the most well-established hypothesis is that the diamond will be formed as a result of metasomatosis. According to this theory, the source of carbon were fluids of C-H-O-N-S composition. There are still questions concerning the environment for diamond crystallization. One of the most common inclusions in diamonds from kimberlite tubes are sulfides. They are also represented in diamondiferous xenoliths of peridotite and eclogite from diamondiferous tubes, but their quantity in diamonds is still higher in comparison with xenoliths. Modern scientific researches allow to assert that large diamonds, such as Kullinan (3106 carats), Koh-i-Noor, etc., were formed at great depths of about 360 – 750 km. Inclusions in these diamonds are, along with silicate minerals, iron-nickel alloy, iron-nickel carbide and sulfide (pyrrhotite). The present study is devoted to studying the model growth environment of a diamond in the Fe-C-S system with a sulfur content of 3 wt. % in relation to iron. The experiments of 0.5 hours duration were carried out at 6 GPa and 1450 С on a high-pressure apparatus of "cutting sphere" type. As a result, diamond synthesis was obtained. The following phases were recorded during the analysis of growth medium composition (metal-sulfide sintering): solid solution of carbon in iron, iron sulfide, iron carbide. Iron sulfide is represented by pyrrhotite. Thus, the phases established in solid products of the experiments fully correspond to the phases isolated from inclusions of natural diamonds.

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12

Yang, Zhijun, Rong Liang, Xiangqing Zeng, and Mingsheng Peng. "A Microscopy and FTIR and PL Spectra Study of Polycrystalline Diamonds from Mengyin Kimberlite Pipes." ISRN Spectroscopy 2012 (April 22, 2012): 1–10. http://dx.doi.org/10.5402/2012/871824.

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The results of a microscopy and FTIR and PL spectra study of the natural polycrystalline diamonds from the Mengyin kimberlite pipes show that they can be classified as the euhedral faceted polycrystalline diamonds (EFPCDs) and anhedral rounded polycrystalline diamonds (ARPCDs). Different diamond grains or their points were formed in different conditions or processes. They were not formed in diamond nucleation stage, but in the diamond growth period. They probably originated from the relatively deeper mantle and were formed in the environment like the peridotitic (P) type diamond single crystals. The EFPCDs did not undergo a remarkable dissolution process during their formation and were possibly fast formed shortly before the kimberlite eruption. The ARPCDs not only were formed at a higher temperature than the EFPCDs but also underwent a notable dissolution process and had been stored relatively longer in the mantle. Fluids or melts probably participated in the formation of the ARPCDs or modified them during the period of their storage in the mantle.

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Shkodzinsky, V. S. "ORIGIN OF AUTONOMOUS DIAMOND PLACERS." Geology and mineral resources of Siberia, no. 4 (December 2022): 64–69. http://dx.doi.org/10.20403/2078-0575-2022-4-64-69.

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The obtained evidences of the hot accretion of Earth indicates that kimberlites, lamproites and diamonds were formed from residual melts of the bottom peridotite parts in global magmatic ocean generated as a result of the huge impact heat input during accretion. Rhombic-dodecahedron and rounded diamonds, characteristic of autonomous placers with an unknown mother lode, appeared in relatively silicic acid-rich viscous magmas. The low content of carbon dioxide in them led to a small boiling depth, decompression solidification and explosion of solidified parts of rising pyrogeic columns under the influence of the high internal pressure of gas phase preserved by solidification and to the formation of explosive diatremes insignificant in volume. Therefore, explosion products were ejected mainly onto the Earth’s surface and formed diamond tuffs and tuffizites. Their wash out has led to the formation of autonomous diamond placers, for which it is not possible to find kimberlite pipes, the supposed mother lodes of diamonds.

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14

Palyanov, Yury N., Alexander G. Sokol, Anatoly A. Tomilenko, and Nikolay V. Sobolev. "Conditions of diamond formation through carbonate-silicate interaction." European Journal of Mineralogy 17, no. 2 (April 29, 2005): 207–14. http://dx.doi.org/10.1127/0935-1221/2005/0017-0207.

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Guignard, Jérémy, Mythili Prakasam, and Alain Largeteau. "A Review of Binderless Polycrystalline Diamonds: Focus on the High-Pressure–High-Temperature Sintering Process." Materials 15, no. 6 (March 16, 2022): 2198. http://dx.doi.org/10.3390/ma15062198.

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Nowadays, synthetic diamonds are easy to fabricate industrially, and a wide range of methods were developed during the last century. Among them, the high-pressure–high-temperature (HP–HT) process is the most used to prepare diamond compacts for cutting or drilling applications. However, these diamond compacts contain binder, limiting their mechanical and optical properties and their substantial uses. Binderless diamond compacts were synthesized more recently, and important developments were made to optimize the P–T conditions of sintering. Resulting sintered compacts had mechanical and optical properties at least equivalent to that of natural single crystal and higher than that of binder-containing sintered compacts, offering a huge potential market. However, pressure–temperature (P–T) conditions to sinter such bodies remain too high for an industrial transfer, making this the next challenge to be accomplished. This review gives an overview of natural diamond formation and the main experimental techniques that are used to synthesize and/or sinter diamond powders and compact objects. The focus of this review is the HP–HT process, especially for the synthesis and sintering of binderless diamonds. P–T conditions of the formation and exceptional properties of such objects are discussed and compared with classic binder-diamonds objects and with natural single-crystal diamonds. Finally, the question of an industrial transfer is asked and outlooks related to this are proposed.

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Spetsius, Zdzislaw, Ludmila Liskovaya, Alexander Ivanov, and Irina Bogush. "FEATURES OF GARNET AND CLINOPYROXENE IN DIAMONDIFEROUS ECLOGITES FROM THE UDACHNAYA KIMBERLITE PIPE, YAKUTIA: METASOMATOSIS EVIDENCE." Ores and metals, no. 4 (February 2, 2021): 45–53. http://dx.doi.org/10.47765/0869-5997-2020-10027.

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Mineralogy of diamondiferous eclogite xenolites showing metasomatosis evidence from the Udachnaya kimberlite pipe is discussed. The paper also reviews features of diamonds they contain, compositions of primary garnets and omphacites as well as alteration of structural and species compositions of original garnets and clinopyroxenes during metasomatosis. Based on pyrope structure update, two-phase garnet composition is suggested, which is mostly represented by complex pyrope associated with Ca-pyrope. In all samples, primary omphacite is replaced by another clinopyroxene variety depleted in Na2O, which is typical of partial melting products. Geothermometry results suggested that the eclogites formed within a temperature range of 1,000–1,2000 °C. Based on diamond morphology, data on total N content in diamonds and its aggregation, multiple stages of diamond formation in eclogites and the most probable growth of later diamond generations impacted by metasomatizing mantle fluids containing carbon are postulated. It is suggested that certain diamond formation stages probably had a time gap of several hundred million years.

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Sun, Kaiyue, Taijin Lu, Mingyue He, Zhonghua Song, Jian Zhang, and Jie Ke. "Morphological and Surface Microtopographic Features of HPHT-Grown Diamond Crystals with Contact Twinning." Crystals 12, no. 9 (September 6, 2022): 1264. http://dx.doi.org/10.3390/cryst12091264.

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Gem-grade twinned high-pressure high-temperature (HPHT) synthetic diamond crystals are rare. Hence, few investigations on their morphological features and formation have been reported. In this article, the morphological and surface microtopographic features of HPHT synthetic-diamond crystals contact twinning is detailed and investigated. It indicates that twins of diamond forming and nucleating during the early stages of the growth and the development of {100} and {111} growth sectors on either side of such boundaries proceeds independently, which affects the final morphology of the diamond crystals. According to the different features of crystal macroscopic morphological properties, two kinds of twin model have been established. The formation of twin crystals changed the lattice of diamonds with face-centered cubic dimensions. The type of diamond lattice at the twin boundary is hexagonal and closely packed, which has potential for further developing the application of synthetic diamond twin crystals.

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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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Simakov, S. "Type IIa diamond formation." Доклады академии наук 482, no. 5 (October 2018): 583–86. http://dx.doi.org/10.31857/s086956520003037-3.

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Harris, Stephen J., David N. Belton, Anita M. Weiner, and Steven J. Schmieg. "Diamond formation on platinum." Journal of Applied Physics 66, no. 11 (December 1989): 5353–59. http://dx.doi.org/10.1063/1.343729.

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Simakov, S. K. "Type IIa Diamond Formation." Doklady Earth Sciences 482, no. 2 (October 2018): 1336–38. http://dx.doi.org/10.1134/s1028334x18100197.

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Bulanova, G. P. "The formation of diamond." Journal of Geochemical Exploration 53, no. 1-3 (March 1995): 1–23. http://dx.doi.org/10.1016/0375-6742(94)00016-5.

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23

Bayarjargal, Lkhamsuren, Tatyana G. Shumilova, Alexandra Friedrich, and Björn Winkler. "Diamond formation from CaCO3 at high pressure and temperature." European Journal of Mineralogy 22, no. 1 (March 18, 2010): 29–34. http://dx.doi.org/10.1127/0935-1221/2010/0021-1986.

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Davis, Lilian H. "The Diamond Datascram Diaries: Formation-Diamond Datascram Development." Employment Relations Today 44, no. 3 (December 2017): 51–60. http://dx.doi.org/10.1002/ert.21640.

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Zheng, You Jin, Hai Liang Huang, Xiao Peng Jia, and Hong An Ma. "Influences of Additive Si on the Synthesis of Diamonds Using Fe Power as Catalyst." Advanced Materials Research 335-336 (September 2011): 464–67. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.464.

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In this paper, industrial diamonds using pure Fe powder catalyst with additive Si has been synthesized by HPHT method. Optical microscope, XRD and SEM were utilized for observation and detection. The influences of additive Si on the synthesis have been investigated from several aspects such as the diamond-forming conditions, the composition of synthesized sample and inclusions in diamond, and the morphology character of diamonds etc. The results indicate that the formation of SiC, which should have been in a solid state during the synthesis.

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Gong, Jian Hong, Shu Xia Lin, and Jun Gao. "TEM and DSC Studies on the Synthetic Diamond Grown from Fe-Ni-C-B System under HPHT." Advanced Materials Research 320 (August 2011): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amr.320.3.

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Transmission Electron Microscope (TEM) and Different Scanning Calorimetry (DSC) Methods Were Used to Investigate the Diamonds Grown with Different Boron Content Alloy Catalysts under High-Pressure High-Temperature (HPHT). Experimental Results Demonstrated the Microstructure and Composition of Boride Compounds in Synthetic Diamond, such as (FeNi)23(CB)6 ,(Fe, Ni)3(C,B), (Fe,Ni)B and B4C, Whose Formation Process Was Analyzed. the Thermal Stability of Diamond Depends on Boron Concentration in Catalyst According to DSC Studies. we Analyzed the Reason of Diamond Oxidation.The Work Offers Valuable Information for Improving the Thermal Stability of Synthetic Diamond Crystals by Adjusting Boron Content in the Fe-Ni Based Catalyst.

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Venter, Andrew M., Vladimir Luzin, Marco A. G. Andreoli, Sandra Piazolo, and Tshegofatso Moipolai. "Non-Destructive Residual Stress Investigations of Natural Polycrystalline Diamonds." Advanced Materials Research 996 (August 2014): 969–74. http://dx.doi.org/10.4028/www.scientific.net/amr.996.969.

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Three natural polycrystalline diamond samples have been investigated non-destructively in their raw as-discovered forms. The samples originate from different locations in the world and possibly have different mechanisms of formation. The study reveals that the stones are primarily composed of cubic diamond with varying amounts of impurities that emanate from their excessive porosities and entrapped environmental contamination from the areas they were formed and subsequently discovered. Residual stress analyses with X-ray and neutron diffraction techniques of the diamond phase in the interior regions of the diamonds revealed low stress values.

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Sun, Chengyang, Taijin Lu, Mingyue He, Zhonghua Song, and Yi Deng. "Corresponding relationship between characteristic birefringence, strain, and impurities in Zimbabwean mixed-habit diamonds revealed by mapping techniques." European Journal of Mineralogy 34, no. 6 (November 9, 2022): 539–47. http://dx.doi.org/10.5194/ejm-34-539-2022.

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Abstract. Birefringence in diamond is an optical phenomenon related to strain and various defects in crystal lattices. Despite extensive investigations being done to characterize and quantify it, there is still controversy about its origin in diamond lattices. Here we report the relationship between the distribution of birefringence patterns observed under cross-polarized light, strain features analyzed by Raman mapping, and the impurity characteristics revealed by Fourier transform infrared spectroscopy (FTIR) mapping in natural mixed-habit diamonds. It was deduced that the plastic deformation was enhanced with higher tensile residual stress, and nitrogen and VN3H defects were more enriched as a result of the temperature increase during crystallization, at growth bands showing straight birefringence patterns and the relative enrichment of graphite inclusions. These results provided solid data and insights for birefringence-related properties in diamond and correlated the occurrence of birefringence with diamond spectroscopic properties, which promoted the understanding of the formation of birefringence in natural diamonds and would be helpful for the synthesis of high-quality, birefringence-free diamonds.

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Nefedov, Yuriy Viktorovich, and Igor Vyacheslavovich Klepikov. "Occurrence Regularities of Nitrogen Defects in the Ural Type Crystal Diamonds from Different Regions." Key Engineering Materials 769 (April 2018): 201–6. http://dx.doi.org/10.4028/www.scientific.net/kem.769.201.

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The collection of the Ural, Anabar and Brazilian diamonds is studied by infrared spectrometry method. For the reconstruction of the thermal formation conditions of diamond crystals, V. Taylor’s diagrams are made with the calculated isotherms. Graphs of the ratio of B1 and B2 defects are drawn. Conclusions about the thermal conditions of the Ural diamonds formation and their possible affinity to the specific and type of indigenous sources are made.

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Borzdov, Yuri M., Alexander F. Khokhryakov, Igor N. Kupriyanov, Denis V. Nechaev, and Yuri N. Palyanov. "Crystallization of Diamond from Melts of Europium Salts." Crystals 10, no. 5 (May 7, 2020): 376. http://dx.doi.org/10.3390/cryst10050376.

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Diamond crystallization in melts of europium salts (Eu2(C2O4)3·10H2O, Eu2(CO3)3·3H2O, EuCl3, EuF3, EuF2) at 7.8 GPa and in a temperature range of 1800–2000 °C was studied for the first time. Diamond growth on seed crystals was realized at a temperature of 2000 °C. Spontaneous diamond nucleation at these parameters was observed only in an Eu oxalate melt. The maximum growth rate in the europium oxalate melt was 22.5 μm/h on the {100} faces and 12.5 μm/h on the {111} faces. The diamond formation intensity in the tested systems was found to decrease in the following sequence: Eu2(C2O4)3·10H2O > Eu2(CO3)3·3H2O > EuF3 > EuF2 = EuCl3. Diamond crystallization occurred in the region of stable octahedral growth in melts of Eu3+ salts and in the region of cubo-octahedral growth in an EuF2 melt. The microrelief of faces was characterized by specific features, depending on the system composition and diamond growth rate. In parallel with diamond growth, the formation of metastable graphite in the form of independent crystals and inclusions in diamond was observed. From the spectroscopic characterization, it was found that diamonds synthesized from Eu oxalate contain relatively high concentrations of nitrogen (about 1000−1200 ppm) and show weak PL features due to inclusions of Eu-containing species.

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O'Keefe, Michael A., David Blake, Friedemann Freund, Crispin Hetherington, and John Turner. "Enhancement of structure of interstellar diamond microcrystals by image processing." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 836–37. http://dx.doi.org/10.1017/s0424820100106247.

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Since the discovery of 0.5-7.5 nm diamond crystals in oxidized acid residues of carbonaceous chondrites much speculation has centered on the mechanism of their origin. Indeed; there is even some difference of opinion regarding the presence of “amorphous low-atomic number phases” intimately associated with the diamond crystallites. While the diamond-containing residue from the meteorites comprises only 50-200 ppm of the total meteorite mass, theories regarding the genesis of the diamonds have far-reaching consequences since noble gas isotopic data indicate that they predate the solar system and are from an interstellar source. Lewis et al. propose that the diamonds formed under low pressure conditions by processes similar to those used in recent low-pressure CVD laboratory syntheses. Blake et al. propose a second mechanism of formation, within the stability field of diamond, due to particle-particle collisions behind supernova shock waves. At the present time, no data exist which unequivocally support one model over the other.

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Bae, Mun Ki, Chi Hwan Kim, Yeong Min Park, Su Jong Yoon, and Tae Gyu Kim. "Heat resistance properties of various boron-doped diamond films prepared via hot filament chemical vapor deposition." Modern Physics Letters B 34, no. 07n09 (March 16, 2020): 2040045. http://dx.doi.org/10.1142/s021798492040045x.

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We used hot filament chemical vapor deposition to synthesize conductive diamond layers. Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD) were employed to explore how boron affected diamond formation in terms of structural chemistry, surface appearance, and growth rate. As the boron/carbon (B/C) ratio increased, thin boron-doped diamonds (BDDs) exhibited increased levels of amorphous carbon. We used a high-temperature furnace to explore the heat resistance of BDDs.

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Liu, Fei, Dongyang Lian, Weiwei Wu, and Jingsui Yang. "Diamond and Other Exotic Mineral-Bearing Ophiolites on the Globe: A Key to Understand the Discovery of New Minerals and Formation of Ophiolitic Podiform Chromitite." Crystals 11, no. 11 (November 8, 2021): 1362. http://dx.doi.org/10.3390/cryst11111362.

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Ophiolite-hosted diamond from peridotites and podiform chromitites significantly differs from those of kimberlitic diamond and ultra-high pressure (UHP) metamorphic diamond in terms of occurrence, mineral inclusion, as well as carbon and nitrogen isotopic composition. In this review, we briefly summarize the global distribution of twenty-five diamond-bearing ophiolites in different suture zones and outline the bulk-rock compositions, mineral and particular Re-Os isotopic systematics of these ophiolitic chromitites and host peridotites. These data indicate that the subcontinental lithospheric mantle is likely involved in the formation of podiform chromitite. We also provide an overview of the UHP textures and unusual mineral assemblages, including diamonds, other UHP minerals (e.g., moissanite, coesite) and crustal minerals, which robustly offer evidence of crustal recycling in the deep mantle along the suprasubduction zone (SSZ) and then being transported to shallow mantle depths by asthenospheric mantle upwelling in mid-ocean-ridge and SSZ settings. A systematic comparison between four main genetic models provides insights into our understanding of the origin of ophiolite-hosted diamond and the formation of podiform chromitite. Diamond-bearing peridotites and chromitites in ophiolites are important objects to discover new minerals from the deep earth and provide clues on the chemical composition and the physical condition of the deep mantle.

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Sharin, P. P., M. P. Akimova, and S. P. Yakovleva. "Structural-Phase State of the Diamond-Matrix Transition Zone in Hard-Alloy Diamond-Containing Composites with Diffusion Metallization of Diamonds during Sintering with Impregnation." Materials Science Forum 945 (February 2019): 763–70. http://dx.doi.org/10.4028/www.scientific.net/msf.945.763.

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The conducted study belongs to a field of fundamental and application-oriented issues of interphase interaction and formation of interfacial layers between a filler and matrix during the synthesis of composite systems. The factors determining the strength of the diamonds retention in a hard-alloy matrix of abrasive composites obtained by the hybrid synthesis technology with thermal diffusion metallization of diamond particles and sintering by a scheme of the self-metering impregnation were studied. Chemical composition, morphology and distribution of the reaction products, the nature of the resulting carbon phases in the contact zone between the diamond and matrix were investigated using scanning electron microscopy, X-ray phase analysis, Raman spectroscopy and atomic force microscopy. It was found that the increase of physical and chemical adhesion of diamond with the matrix during the synthesis of composites by the developed technology occurs due to the formation of high nano- and submicronic roughness of the diamond surface, formation of island-type metallized coating, dense filling of gaps by nanoscale layers of metal-infiltrate. Free carbon (graphite) was found in small quantities in the form of micron dimension separate inclusions. The revealed multilevel hierarchy of the high-structured morphological forms of the elements of the transitional layers has provided the solidity and strength of the joint between diamond and matrix.

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Vasilev, Evgeny. "Defects of diamond crystal structure as an indicator of crystallogenesis." Записки Горного института 250 (September 29, 2021): 481–91. http://dx.doi.org/10.31897/pmi.2021.4.1.

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Based on the study of a representative collections of diamonds from diamondiferous formations of the Urals and deposits of the Arkhangelsk and Yakutian diamond provinces, we established patterns of zonal and sectoral distribution of crystal structure defects in crystals of different morphological types, identified the specifics of crystals formed at different stages of crystallogenesis and performed a comprehensive analysis of constitutional and population diversity of diamonds in different formations. We identified three stages in the crystallogenesis cycle, which correspond to normal and tangential mechanisms of growth and the stage of changing crystal habit shape. At the stage of changing crystal habit shape, insufficient carbon supersaturation obstructs normal growth mechanism, and the facets develop from existing surfaces. Due to the absent stage of growth layer nucleation, formation of new {111} surfaces occurs much faster compared to tangential growth mechanism. This effect allows to explain the absence of cuboids with highly transformed nitrogen defects at the A-B1 stage: they have all been refaceted by a regenerative mechanism. Based on the revealed patterns, a model of diamond crystallogenesis was developed, which takes into account the regularities of growth evolution, thermal history and morphological diversity of the crystals. The model implies the possibility of a multiply repetitive crystallization cycle and the existence of an intermediate chamber; it allows to explain the sequence of changes in morphology and defect-impurity composition of crystals, as well as a combination of constitutional and population diversity of diamonds from different geological formations.

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Izraeli, E. S., J. W. Harris, and O. Navon. "Raman barometry of diamond formation." Earth and Planetary Science Letters 173, no. 3 (November 1999): 351–60. http://dx.doi.org/10.1016/s0012-821x(99)00235-6.

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Kudryavtsev, Yu P., N. A. Bystrova, L. V. Zhirova, and A. L. Rusanov. "Formation of diamond from carbyne." Russian Chemical Bulletin 45, no. 1 (January 1996): 233–34. http://dx.doi.org/10.1007/bf01433770.

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Perry, John, Stephen Nelson, and Satoru Hosomi. "Diamond formation in solid metal." Materials Research Bulletin 25, no. 6 (June 1990): 749–56. http://dx.doi.org/10.1016/0025-5408(90)90203-e.

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Valencia, Felipe J., Rafael I. González, Eduardo M. Bringa, and Miguel Kiwi. "Hillock formation on nanocrystalline diamond." Carbon 119 (August 2017): 219–24. http://dx.doi.org/10.1016/j.carbon.2017.04.020.

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Zedgenizov, Dmitry, Irina Bogush, Vladislav Shatsky, Oleg Kovalchuk, Alexey Ragozin, and Viktoriya Kalinina. "Mixed-Habit Type Ib-IaA Diamond from an Udachnaya Eclogite." Minerals 9, no. 12 (November 29, 2019): 741. http://dx.doi.org/10.3390/min9120741.

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The variety of morphology and properties of natural diamonds reflects variations in the conditions of their formation in different mantle environments. This study presents new data on the distribution of impurity centers in diamond type Ib-IaA from xenolith of bimineral eclogite from the Udachnaya kimberlite pipe. The high content of non-aggregated nitrogen C defects in the studied diamonds indicates their formation shortly before the stage of transportation to the surface by the kimberlite melt. The observed sectorial heterogeneity of the distribution of C- and A-defects indicates that aggregation of nitrogen in the octahedral sectors occurs faster than in the cuboid sectors.

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Cao, Chuqi, Jingsui Yang, Fengshan Zeng, Fei Liu, Shengbiao Yang, and Yun Wang. "Morphology and FTIR Characteristics of the Alluvial Diamond from the Yangtze Craton, China." Crystals 12, no. 4 (April 12, 2022): 539. http://dx.doi.org/10.3390/cryst12040539.

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A total of 48 natural alluvial diamonds from the Yangtze Craton, China, also called Hunan diamonds, were studied using morphology and IR spectroscopy. These diamond samples, collected downstream of the Yuan River, Hunan Province, with unknown host-rock source(s), were observed by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR). Most Hunan diamonds are monocrystal forms of octahedra, tetrahexahedra (THH) and dodecahedra; octahedral–rhom-dodecahedral transitional behaviors and irregular forms are also visible. Trigons and tetragons, terraces and shield-shaped laminae are surface features that frequently indicate dissolution and reabsorption; green and brown spots, network patterns, and other mechanical abrasion marks are typical evidence of long-time deposition and transportation of Hunan diamonds. The main types of Hunan diamonds are type IaAB and type Ⅱa. Diamond samples have a wide range of total nitrogen content (Ntot) from 196–1094 ppm. Two populations are distinguished by two-peak distribution models of NA (A-center concentrations) and %B (proportion of aggregated nitrogen). Hunan diamonds are low in structure hydrogen (0.03–4.67 cm−1, mostly below 1 cm−1) and platelets (0.23–17 cm−1, mostly below 2 cm−1). Moreover, there is a significant positive correlation between the hydrogen correlation peak and Ntot, which is similar to Argyle diamonds. The temperature conditions of the diamond formation have been estimated at 1075–1180 °C, mainly conforming to the kimberlite diamond range. Besides, some samples with slightly higher temperatures are close to the ultramafic-related Juina diamonds. Therefore, the FTIR characteristics analysis and comparison indicate the multiple sources of Hunan diamonds.

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Chanturia, Valentin, Valery Morozov, Galina Dvoichenkova, and Elena Chanturia. "Increasing the recoverability of diamonds in the process of x-ray luminescent separation using phosphor-containing compositions." Sustainable Development of Mountain Territories 14, no. 3 (September 30, 2022): 410–21. http://dx.doi.org/10.21177/1998-4502-2022-14-3-410-421.

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Introduction. A promising way to solve the problem of reducing the losses of weakly and abnormally luminescent diamonds in the process of X-ray luminescent separation is to modify their spectral characteristics with special compositions of phosphors. The phosphor-containing compositions used include inorganic and organic phosphors that provide the necessary change in the kinetic characteristics of the diamond X-ray luminescence signal. The purpose of the work. Investigation of the mechanism of the process and selection of compositions of phosphorcontaining compositions that provide the required modification of spectral characteristics and increase the extraction of weakly and abnormally luminescent diamonds in the process of X-ray-luminescent separation. Methodology results. Studies of the mechanism of formation of the X-ray luminescence signal from diamond-phosphor complexes were carried out by determining the degree of coating of the surface of diamonds with phosphors by the visiometric method and the amplitude of the luminescence signal with varying concentrations of phosphor in the emulsion. The effectiveness of the selected compositions of the phosphor-containing composition was evaluated by determining and comparative analysis of the acquired spectral and kinetic characteristics of the diamond-phosphor complexes using the Polyus–M separator. The evaluation of the effectiveness of the selected formulations was determined by the results of a test on industrial X-ray luminescent separators. Research results. The mechanism of formation of the X-ray luminescence signal from a diamond with a phosphorcontaining composition fixed on its surface is determined. It is shown that the total signal is the sum of the diamond and phosphor signals attenuated by screening and scattering of luminescent radiation by 5-15% for the diamond signal and 20-40% for the phosphor signal. The use of inorganic phosphors based on zinc sulfide, or a mixture of phosphor based on zinc orthosilicate and anthracene in compositions is justified, providing an increase in the intensity of the X-ray luminescence signal of a weakly luminescent diamond by 2.5 times, and preserving the shape of the X-ray luminescence signal of natural diamonds. It is proposed to use catalytic cracking as a collector of a diesel fraction compound and heavy gas oil, which ensures effective fixation of the phosphor on the surface of diamonds. The composition of the composition (FL-530, anthracene, diesel fraction, THCC) is proposed, which provides the required modification of spectral characteristics and detection of low-luminous diamonds. Resume. The results of the tests carried out on diamonds of various sizes have established the possibility of increasing the extraction of diamonds by 5-15% due to the detection of diamond crystals with weak or abnormal luminescence. At the same time, the required selectivity of the process with respect to kimberlite minerals is maintained. Conclusions. The results of the research are recommended for practical implementation in X-ray luminescent separation schemes at ALROSA processing plants to reduce losses of weakly and abnormally luminescent diamonds and will also be used in further studies of the possibility of increasing the selectivity of separation of diamonds and rock minerals during kimberlite enrichment.

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Nestola, Fabrizio, Cyrena A. Goodrich, Marta Morana, Anna Barbaro, Ryan S. Jakubek, Oliver Christ, Frank E. Brenker, et al. "Impact shock origin of diamonds in ureilite meteorites." Proceedings of the National Academy of Sciences 117, no. 41 (September 28, 2020): 25310–18. http://dx.doi.org/10.1073/pnas.1919067117.

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The origin of diamonds in ureilite meteorites is a timely topic in planetary geology as recent studies have proposed their formation at static pressures >20 GPa in a large planetary body, like diamonds formed deep within Earth’s mantle. We investigated fragments of three diamond-bearing ureilites (two from the Almahata Sitta polymict ureilite and one from the NWA 7983 main group ureilite). In NWA 7983 we found an intimate association of large monocrystalline diamonds (up to at least 100 µm), nanodiamonds, nanographite, and nanometric grains of metallic iron, cohenite, troilite, and likely schreibersite. The diamonds show a striking texture pseudomorphing inferred original graphite laths. The silicates in NWA 7983 record a high degree of shock metamorphism. The coexistence of large monocrystalline diamonds and nanodiamonds in a highly shocked ureilite can be explained by catalyzed transformation from graphite during an impact shock event characterized by peak pressures possibly as low as 15 GPa for relatively long duration (on the order of 4 to 5 s). The formation of “large” (as opposed to nano) diamond crystals could have been enhanced by the catalytic effect of metallic Fe-Ni-C liquid coexisting with graphite during this shock event. We found no evidence that formation of micrometer(s)-sized diamonds or associated Fe-S-P phases in ureilites require high static pressures and long growth times, which makes it unlikely that any of the diamonds in ureilites formed in bodies as large as Mars or Mercury.

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Alba, Gonzalo, M. Pilar Villar, Rodrigo Alcántara, Javier Navas, and Daniel Araujo. "Surface States of (100) O-Terminated Diamond: Towards Other 1 × 1:O Reconstruction Models." Nanomaterials 10, no. 6 (June 18, 2020): 1193. http://dx.doi.org/10.3390/nano10061193.

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Diamond surface properties show a strong dependence on its chemical termination. Hydrogen-terminated and oxygen-terminated diamonds are the most studied terminations with many applications in the electronic and bioelectronic device field. One of the main techniques for the characterization of diamond surface terminations is X-ray photoelectron spectroscopy (XPS). In this sense, the use of angle-resolved XPS (ARXPS) experiments allows obtaining depth-dependent information used here to evidence (100)-O-terminated diamond surface atomic configuration when fabricated by acid treatment. The results were used to compare the chemistry changes occurring during the oxidation process using a sublayer XPS intensity model. The formation of non-diamond carbon phases at the subsurface and higher oxygen contents were shown to result from the oxygenation treatment. A new (100) 1 × 1:O surface reconstruction model is proposed to explain the XPS quantification results of O-terminated diamond.

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Simakov, S. K. "Metastable nanosized diamond formation from a C-H-O fluid system." Journal of Materials Research 25, no. 12 (December 2010): 2336–40. http://dx.doi.org/10.1557/jmr.2010.0303.

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The model of nanosized diamond particles formation at metastable P-T parameters from a C-H-O fluid system is presented. It explains the hydrothermal formation and growth of diamond and the specifics of chemical vapor deposition (CVD) diamond synthesis gas mixtures at low P-T parameters. Further, the model explains the genesis of interstellar nanodiamond formations in space and the genesis of metamorphic microdiamonds in shallow depth Earth rocks. In contrast to models where many possible reactions are considered, the present model makes the simplest possible assumptions about the key processes, and is then able to account for various tendencies seen in experimental data.

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Leost, I., T. Stachel, G. P. Brey, J. W. Harris, and I. D. Ryabchikov. "Diamond formation and source carbonation: mineral associations in diamonds from Namibia." Contributions to Mineralogy and Petrology 145, no. 1 (February 7, 2003): 15–24. http://dx.doi.org/10.1007/s00410-003-0442-5.

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Semikina, T. V. "Diamond microcrystallites formation through the phase transition graphite→liquid→diamond." Semiconductor Physics, Quantum Electronics & Optoelectronics 9, no. 1 (March 1, 2006): 22–28. http://dx.doi.org/10.15407/spqeo9.01.022.

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Lebedev, Vasily T., Fedor M. Shakhov, Alexandr Ya Vul, Arcady A. Zakharov, Vladimir G. Zinoviev, Vera A. Orlova, and Eduard V. Fomin. "X-ray Excited Optical Luminescence of Eu in Diamond Crystals Synthesized at High Pressure High Temperature." Materials 16, no. 2 (January 15, 2023): 830. http://dx.doi.org/10.3390/ma16020830.

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Powder diamonds with integrated europium atoms were synthesized at high pressure (7.7 GPa) and temperature (1800 °C) from a mixture of pentaerythritol with pyrolyzate of diphthalocyanine (C64H32N16Eu) being a special precursor. In diamonds prepared by X-ray fluorescence spectroscopy, we have found a concentration of Eu atoms of 51 ± 5 ppm that is by two orders of magnitude greater than that in natural and synthetic diamonds. X-ray diffraction, SEM, X-ray exited optical luminescence, and Raman and IR spectroscopy have confirmed the formation of high-quality diamond monocrystals containing Eu and a substantial amount of nitrogen (~500 ppm). Numerical simulation has allowed us to determine the energy cost of 5.8 eV needed for the incorporation of a single Eu atom with adjacent vacancy into growing diamond crystal (528 carbons).

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Roy, Rustum, D. Ravichandran, P. Ravindranathan, and A. Badzian. "Evidence for hydrothermal growth of diamond in the C–H–O and C–H–O halogen system." Journal of Materials Research 11, no. 5 (May 1996): 1164–68. http://dx.doi.org/10.1557/jmr.1996.0150.

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Powder x-ray diffraction (XRD) and Raman evidence are presented for the formation of crystalline diamond in the “hydrothermal” pressure-temperature regime 1–5 kbars, <1000 °C. Two different methods appear to enable diamond to nucleate and grow. One—a Low Pressure Solid-State Source (LPSSS) route—utilizes special solid precursors, especially low temperature glassy carbon (GC-500), with very fine diamond seeds in sealed gold capsules with H2O at, say, 800 °C and 1 kbar. The other includes pyrolysis of highly selected organic solid/liquid precursors (halogenated aliphatics such as iodoform) onto similar diamond seeds. In all the cases, powder x-ray diffraction evidence shows a marked increase of the diamond XRD peaks, likewise the Raman spectrum shows a strong increase of the 1331 cm−1 line. However, the crystals apparently are too small to be seen in the SEM. TEM diffraction data, on the other hand, seem to lend support to the possibility of all the grown diamonds being very small.

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Yuan, Xiaolu, Jiangwei Liu, Jinlong Liu, Junjun Wei, Bo Da, Chengming Li, and Yasuo Koide. "Reliable Ohmic Contact Properties for Ni/Hydrogen-Terminated Diamond at Annealing Temperature up to 900 °C." Coatings 11, no. 4 (April 17, 2021): 470. http://dx.doi.org/10.3390/coatings11040470.

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Ohmic contact with high thermal stability is essential to promote hydrogen-terminated diamond (H-diamond) electronic devices for high-temperature applications. Here, the ohmic contact characteristics of Ni/H-diamond at annealing temperatures up to 900 °C are investigated. The measured current–voltage curves and deduced specific contact resistance (ρC) are used to evaluate the quality of the contact properties. Schottky contacts are formed for the as-received and 300 °C-annealed Ni/H-diamonds. When the annealing temperature is increased to 500 °C, the ohmic contact properties are formed with the ρC of 1.5 × 10−3 Ω·cm2 for the Ni/H-diamond. As the annealing temperature rises to 900 °C, the ρC is determined to be as low as 6.0 × 10−5 Ω·cm2. It is believed that the formation of Ni-related carbides at the Ni/H-diamond interface promotes the decrease in ρC. The Ni metal is extremely promising to be used as the ohmic contact electrode for the H-diamond-based electronic devices at temperature up to 900 °C.

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Journal articles on the topic 'Diamond formation'

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