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Study on the diamond/ultrafine WC-Co cermets interface formed in a SPS consolidated composite

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Rare Metals 2006年第2期25卷 150-155页

作者： SHI Xiaoliang SHAO Gangqin DUAN Xinglong YUAN Runzhang State Key Laboratory of Advanced Technology for Materials Synthesis ＆ Processing Wuhan University of Technology Wuhan 430070 China

Nanocrystalline WC-Co composite powder and coated tungsten diamond by using vacuum vapor deposition were consolidated by the spark plasma sintering （SPS） process to prepare diamond-enhanced WC-Co cemented carbide composite materials. The interface microstructures between coated tungsten diamond and WC-Co cemented carbide matrix were investigated by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）. The results showed that there is a transitional layer between the diamond and the matrix, in which the carbon content is 62.97wt.%, and the content of cobalt in the transitional zone is 6.19wt.%; the content of cobalt in the WC-Co cemented carbide matrix is 6.07wt.%, in which the carbon content is 15.95wt.%, and the content of cobalt on the surface of diamond is 7.30wt.%, in which the carbon content is 80.38wt.%. The transitional zone prevents the carbon atom of the diamond from spreading to the matrix, in which the carbon content does coincide with the theoretical value of the raw nanocomposite powders, and the carbon content forms a graded distribution among the matrix, transitional zone, and the surface of diamond; after the 1280℃ SPS consolidated process the diamond still maintains a very good crystal shape, the coated tungsten on the surface of the diamond improves thermal stability of the diamond and increases the bonding strength of the interface between the diamond and the matrix.

关键词： diamond nanocrystalline WC-Co composite powders interface spark plasma sintering

diamond-based electron emission:Structure,properties and mechanisms

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Chinese Physics B 2024年第9期33卷 165-177页

作者： Liang-Xue Gu Kai Yang Yan Teng Wei-Kang Zhao Geng-You Zhao Kang-Kang Fan Bo Feng Rong Zhang You-Dou Zheng Jian-Dong Ye Shun-Ming Zhu Kun Tang Shu-Lin Gu School of Electronic Science and Engineering Nanjing UniversityNanjing 210046China

diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,*** with a hydrogen-terminated(H-terminated)surface has a negative electron affinity(NEA)and can easily produce surface electrons from valence or trapped electrons via optical absorption,thermal heating energy or carrier transport in a PN *** NEA of the H-terminated surface enables surface electrons to emit with high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting *** article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA *** electron emission is induced by different physical *** advancements in electron-emitting devices based on diamond are also ***,the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electronemitting devices.

关键词： diamond negative electron affinity(NEA) PN junction electron emission

diamond/c-BN van der Waals heterostructure with modulated electronic structures

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Chinese Physics B 2023年第7期32卷 495-499页

作者：贾素娜李高贤高楠成绍恒李红东 State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China Shenzhen Research Institute Jilin UniversityShenzhen 518057China

The structural and electronic properties of(100),(110), and(111) diamond/cubic boron nitride(c-BN) heterostructures are systematically investigated by first principles calculation. The interface between diamond and c-BN shows the weak van der Waals interactions, which is confirmed by the interface distance and interface binding energy. The diamond/cBN structures are the direct bandgap semiconductors with moderate bandgap values ranging from 0.647 e V to 2.948 e *** work helps to promote the application of diamond in electronic and optoelectronic devices.

关键词： diamond cubic boron nitride heterointerface first principles calculation

diamond Discovered in High-Al Chromitites of the Sartohay Ophiolite,Xinjiang Province,China

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Acta Geologica Sinica(English Edition) 2015年第2期89卷 332-340页

作者： TIAN Yazhou YANG Jingsui Paul T.ROBINSON XIONG Fahui LI Yuan ZHANG Zhongming LIU Zhao LIU Fei NIU Xiaolu CARMA State Key Laboratory for Continental Tectonics and DynamicsInstitute of GeologyChinese Academy of Geological Sciences Institute of Mineral Resources Chinese Academy of Geological Sciences

In recent years diamonds and other exotic minerals have been recovered from mantle peridotites and high-Cr chromitites of a number of ophiolites of different age and different tectonic environments. Here we report a similar collection of minerals from the Sartohay ophiolite of Xinjiang Province, western China, which is characterized by having high-Al chromitites. Several samples of massive podiform chromitite with an aggregate weight of nearly 900 kg yielded diamonds, moissanite and other highly reduced minerals, as well as common crustal minerals. Thus far, more than 20 grains each of diamond and moissanite have been recovered from heavy mineral separates of the chromitites. The diamonds are all 100-200 μm in size and range in color from pale yellow to reddish-orange to colorless. Most of the grains are anhedral to subhedral octahedra, commonly with elongate forms exhibiting well-developed striations. They all display characteristic Raman spectra with shifts between 1325 cm^-1 and 1333 cm^-1, mostly 1331.51 cm^-1 or 1326.96 cm^-1. The moissanite grains are light blue to dark blue, broken crystals, 50-150 μm across, commonly occurring as small flakes or fragments. Their typical Raman spectra have shifts at 762 cm^-1, 785 cm^-1, and 966 cm^-1. This investigation extends the occurrence of diamonds and moissanite to a Paleozoic ophiolite in the Central Asian Orogenic Belt and demonstrates that these minerals can also occur in high-Al chromitites. We conclude that diamonds and moissanite are likely to be ubiquitous in ophiolitic mantle peridotites and chromitites.

关键词： diamond moissanite high-Al chromitite Sartohay Xinjiang

Suppression and compensation effect of oxygen on the behavior of heavily boron-doped diamond films

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Chinese Physics B 2023年第3期32卷 554-560页

作者：郝礼才陈子昂刘东阳赵伟康张鸣汤琨朱顺明叶建东张荣郑有炓顾书林 School of Integrated Circuits Anhui UniversityHefei 230039China School of Electronic Science and Engineering Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics Nanjing UniversityNanjing 210093China

This work investigates the suppression and compensation effect of oxygen on the behaviors and characteristics of heavily boron-doped microwave plasma chemical vapor deposition(MPCVD)diamond *** suppression effect of oxygen on boron incorporation is observed by an improvement in crystal quality when oxygen is added during the diamond doping process.A relatively low hole concentration is expected and verified by Hall effect measurements due to the compensation effect of oxygen as a deep donor in diamond.A low acceptor concentration,high compensation donor concentration and relatively larger acceptor ionization energy are then induced by the incorporation of oxygen;however,a heavily boron-doped diamond film with high crystal quality can also be *** formation of an oxygen–boron complex structure instead of oxygen substitution,as indicated by the results of x-ray photoelectron spectroscopy,is suggested to be more responsible for the observed enhanced compensation effect due to its predicted low formation ***,density functional theory calculations show that the boron–oxygen complex structure is easily formed in diamond with a formation energy of-0.83 *** work provides a comprehensive understanding of oxygen compensation in heavily boron-doped diamond.

关键词： diamond boron–oxygen co-doping incorporation efficiency ionization energy compensation boron–oxygen complex

diamond Polycrystal Powder Formation Directly from Gas Phase in a Plasma Jet System

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Chinese Physics Letters 1993年第6期10卷 359-361页

作者： JIANG Xiangliu QIN Sizhan ZHANG Xiufang XUE Zengquan PANG Shijin Beijing Laboratory of Vacuum Physics Academia SinicaBeijing 100080

diamond polycrystal powder has been produced directly from gas phase in an arc discharge plasma jet *** diluted in argon was used as hydrocarbon source *** product was the mixture of diamond polycrystal powders and *** 3C cubic phase diamond which is dominant,and the mixture phases of cubic and 6H hexagonal diamond are identified in the produced diamond polycrystal powders by electron diffraction patterns.

关键词： powders cubic diamond

diamond: asymmetry leads to continuous hardening

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Science China Materials 2024年第3期67卷 1000-1001页

作者： Zhongchang Wang International Iberian Nanotechnology Laboratory(INL) Braga 4715-330Portugal School of Chemistry Beihang UniversityBeijing 100191China

Naturally occurring and synthetic materials are often polycrystalline comprising various species of grain boundaries(GBs),many of which are randomly *** is known that GBs play a pivotal role in affecting a broad range of material properties,and the nature of GBs is dedicated by grain orientation,growth history and processing conditions.

关键词： conditions diamond continuous

diamond nucleation on surface of C_60 thin layers

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Science China Mathematics 1997年第6期40卷 668-672页

作者：杨国伟袁放成刘大军何金田张兵临 Institute of Modern Physics Xiangtan University Xiangtan 411105 China Department of Physics Zhengzhou University Zhengzhou 450052 China

diamond nucleation on the surface of C60 thin layers and intermediate layer of Si substrates are studied by scanning electron microscopy (SEM). The cross-section SEM images of diamond films show that diamond grains really nucleate on the surface of C60 thin layers. The SEM images of diamond nucleating sites show the nucleating aggregation of diamond on C60 surfaces. The preferential oriented diamond films are observed. The plasma pre-treatment of C60 sublimating layers is a key factor for diamond nucleation.

关键词： C60 diamond nucleation.

Catalytic Effect Analysis of Metallic Catalyst During diamond Single Crystal Synthesis

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 161-167页

作者： Li Li Shibo Xing School of Mechanical and Electrical Engineering Hebei University of Engineering

By transition metals （Fe, Ni, Mn, Co） and their alloys as catalysts during the diamond synthesis, some transition phases will be formed, such as FeaC type carbides and y solid solutions. Based on the empirical electron theory of the solid and molecules, the valence electron structures of different kinds of carbides and y solid solutions and the relative electron density differences of various diamond/carbide and y solid solution/carbide interfaces were calculated and analyzed in this paper. The electron structure conditions of the ideal catalyst were presented by analyzing the different catalytic effects of the catalysts, which provide a new theoretical path to the optimal design of the catalyst composition

关键词： diamond Catalytic effect Carbide Electronic structure