Valence Electron Structure Analysis of Catalyst during Diamond Synthesis under HPHT
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摘要: 在高温高压条件下,金属触媒与石墨形成的碳化物Me3C(Me为Fe、Ni)是形成金刚石结构的主要碳源。利用固体与分子经验电子理论(EET),计算了多种Me3C型碳化物和金刚石的价电子结构以及表征界面性质的电子结构参数,并将程氏理论(TFDC)提出的原子界面边界条件应用到碳化物/金刚石界面,发现碳化物晶胞中CC键络组成的晶面与金刚石中的某些晶面的电子密度在一级近似下是连续的,但不同碳化物其连续程度不同,其中Co3C和(FeNi)3C中碳原子组成晶面的价电子结构与金刚石中的最接近,其CC键转化为金刚石结构需要的能量最低。从电子结构角度上解释了催化机制及不同触媒的催化效果,价电子理论是探讨金刚石催化机制的新途径。Abstract: Experimental results showed that the Me3C (Me means Fe, Ni) pattern carbides produced by the action of catalyst and graphite are main carbon source to form diamond structure under high temperature and high pressure (HPHT). In this paper, based on the empirical electron theory of solids and molecules (EET), the valence electron structure (VES) and interface structure factors of diamond and various carbides are calculated, and the boundary condition of Thomas-Fermi-Dirac-Cheng (TFDC) is applied to the carbide/diamond interfaces. It is found that the electron density of crystal face in Me3C formed by CC bonds is continuous with that of diamond at the first order of approximation, but the continuous intensity of different carbide is different. The VES of plane composed of C atoms in (FeNi)3C and Co3C are more similar to that of diamond, so the energy needed to transform their CC bonds to diamond structure is lower. The catalyst action and catalysis mechanism are explained on the basis of VES concerning the carbides and diamond. This method may be a new way to investigate the mechanism concerning diamond formation.
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Key words:
- diamond single crystal /
- carbide /
- HPHT /
- valence electron structure /
- interface /
- catalyst
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Putyatin A A, Makarova O V, Semenenko K N. Interaction in the Fe-C System at High Pressure and Temperature [J]. Sverkhtverdye Materially, 1989, 11: 1-7. Solozhenko Bladimir L, Turkevich Bladimir Z. Kinetics of Diamond Crystallization from the Melt of the Fe-Ni-C System [J]. J Phys Chem B, 2002, 106(26): 6634-6637. Plvel E, Baluta Gh, Barb D. Complex Carbides in Synthetic Diamond Crystals Produced at Approx 5. 5 GPa [J]. J Mater Sci, 1993, 28(6): 1645-1647. Yin L W, Li M S, Cui J J. Diamond Formation Using Fe3C as a Carbon Source at High Temperature and High Pressure [J]. J Cryst Growth, 2002, 234(1): 1-4. Strong H M, Hanneman R E. Crystallization of Diamond and Graphite [J]. J Chem Phys, 1966, 46: 3668-3672. Lin Q Y, Zhu Y Y, Zhang Y Z, et al. Microanalysis of Metal Film [J]. J Iron Steel Res, 1999, 11(2): 51-54. (in Chinese) 林清英, 朱衍勇, 张燕征, 等. 金属包膜的显微分析 [J]. 钢铁研究学报, 1999, 11(2): 51-54. Xu B, Li M S, Yin L W, et al. Effect of Metallic Film in Diamond Growth from Fe-Ni-C System at High Temperature and High Pressure [J]. Chin Phys Lett, 2003, 20(5): 753-756. Zhang R L. Empirical Electron Theory of Solid and Molecule [M]. Changchun: Jilin Science and Technology Publishing House, 1993: 63-240. (in Chinese) 张瑞林. 固体与分子经验电子理论 [M]. 吉林: 吉林科学技术出版社, 1993: 63-240. Liu Z L, Sun Z G, Li Z L. Application of Yu's and Cheng's Theory to Alloy Research [J]. Progress in Natural Science, 1998, 8(2): 150-160. (in Chinese) 刘志林, 孙振国, 李志林. 余氏理论和程氏理论在合金研究中的应用 [J]. 自然科学进展, 1998, 8(2): 150-160. Cheng K J, Cheng S Y. Application of the TFD Model and Yu's Theory to Material Design [J]. Progress in Natural Science, 1993, 3(5): 417-432. (in Chinese) 程开甲, 程淑玉. TFD模型和余氏理论对材料设计的应用 [J]. 自然科学进展, 1993, 3(5): 417-432. Sun Z G, Li Z L, Liu Z L. Electron Density Calculation on Interface from Different Phases [J]. Chinese Science Bulletin, 1995, 40(4): 2219-2222. (in Chinese) 孙振国, 李志林, 刘志林. 合金异相界面电子密度的计算 [J]. 科学通报, 1995, 40(4): 2219-2222. Liu Z L, Li Z L. Valence Electron Structure of Interfaces and Their Properties [M]. Beijing: Science Press, 2002: 45-88. (in Chinese) 刘志林, 李志林. 界面电子结构与界面性能 [M]. 北京: 科学出版社, 2002: 45-88. Liu Z L, Li Z L, Sun Z G. Catalysis Mechanism and Catalyst Design of Diamond Growth [J]. Metall Mater Trans A, 1999, 30(11): 2757-2766. Xu B, Li M S, Gong J H, et al. Mossbauer Parameters of the Fe-Based Metal Film Surrounding Diamond and Its Catalytic Effect during Diamond Synthesis [J]. Acta Metallurgica Sinica, 2004, 40(80): 810-814. (in Chinese) 许斌, 李木森, 宫建红, 等. Fe基金属包膜的Mossbauer参量及其在金刚石合成中的催化作用 [J]. 金属学报, 2004, 40(80): 810-814. Xu B, Li M S, Cui J J, et al. An Investigation of a Thin Metal Film Covering on HPHT As-Grown Diamond from Fe-Ni-C System [J]. Mater Sci Eng, 2005, (396): 352-359. Xu B, Cui J J, Li M S, et al. Carbide Identification in Different Regions of a Thin Metal Film Covering on an HPHT As-Grown Diamond Single Crystal from Ni-Mn-C System [J]. Chin Phys Lett, 2005, 2(2): 478-481. Hao Z Y, Chen Y F, Zou G T. Synthetic Diamond [M]. Changchun: Jilin University Press, 1996: 95-119. (in Chinese) 郝兆印, 陈宇飞, 邹广田. 人工合成金刚石 [M]. 长春: 吉林大学出版社, 1996: 95-119.
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