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Study on Growth and Characterization of High-quality Large Cubic Gem Diamond Crystals

Author: ChenKui
Tutor: ZuoChuanYi
School: Henan Polytechnic University
Course: Materials Science
Keywords: High temperature and pressure Hexahedral diamond single crystal Crystal growth Growth rate
CLC: TQ164
Type: Master's thesis
Year: 2011
Downloads: 32
Quote: 0
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Abstract


As a high-quality fixed morphology cubic hexahedral diamond single crystal, and other quality diamond single crystal morphology, is also a particularly extensive use limit functional materials, in addition to being widely used in industry, science and technology, national defense, health and other fields, but also have their unique uses, especially as the substrate of single crystal diamond tool knife blanks and CVD synthesis of diamond single crystal. But hexahedral single crystal growth area is very narrow, only about 10 ℃, and at a relatively low temperature region, synthetic crystals tend to trend growth to the high temperature zone of the temperature difference method, single crystals of synthetic hexahedral relatively difficult. In this study, from the choice of experimental materials and metal catalyst start, find a good pressure transmission performance insulation performance good the a% ZrO 2 b% MgO c% MgCaCO 3 the d% AL 2 O 3 composites and homemade develop a the new catalyst Fe x of Ni y Co < sub> z , established by this new material the new assembly B and the homemade catalyst Fe x Ni the y the Co. z phase with reasonable adjustment process can successfully synthesized highly repetitive quality hexahedral diamond single crystal. For the detection of new materials and new catalytic performance of synthetic diamond single crystal, the research with traditional wholly stable ZrO 2 20% MgO material established assembled A commonly used NiMnCo, FeNi catalyst, synthetic diamond single crystal growth zone, the crystal color, quality, growth rate, and a synthesis process appear in a variety of crystal defects were made by the comparison and analysis. Experimental results verify NiMnCo catalyst synthesis hexahedral diamond single crystal, a higher probability of skeletal crystal and spontaneous nuclear excessive, very narrow range of of hexahedral single crystal growth; The assembly method B, crystal growth, the fastest growth rate of 3.6 in mg / h; the octahedral morphology of FeNi catalyst synthetic diamond single crystal region is very wide, the assembly method B, the synthesis of high-quality crystal growth rate is fastest 6.2mg / h; homemade Fe x Ni y Co z catalyst enables synthesis hexahedral single crystal growth temperature range from 10 ℃ to 20 ℃, and can be synthesized in a short time nearly 2 carats heavy quality hexahedral single crystal, its fastest growth rate of up to 7.8mg / h. Found carat diamond single crystal with 0.5 x 0.5mm 2 Seeding growth compared with the growth rate of Japan's Sumitomo synthetic diamond single crystal, this study synthetic crystals for 27h growth rate of 7.4mg / h, the Japanese Sumitomo synthetic time to 64h, the crystal growth rate of about 3.2 mg / h, 5 × 5mm 2 seed law needed to synthetic carat crystal growth 32h, and the crystal growth rate to 6.25mg / h. The visible quality hexahedral monocrystalline growth rate of synthesis of this study have been far more than Japan's Sumitomo. Synthetic diamond single crystal in the case compared with the Japanese Sumitomo and Element Six diamond sample, were made by the following tests: a high magnification metallographic observation found on the surface of the crystal, the interior of crystals of the present research synthesis unless trace impurity In addition, the surface is smooth and translucent color distribution than the uniform Sumitomo of Japan and Element Six samples, three samples, the crystal surface have left traces of processing. The samples were laser Raman tests found that the size of the FWHM values ??of the three samples were: Japan's Sumitomo to 5.298cm -1 , Element Six 5.837cm -1 this study, synthetic crystal 5.570cm -1 , the Japanese Sumitomo diamond single crystal FWHM minimum, its crystal lattice relatively perfect. FTIR microspectroscopy test basis, this study synthetic crystals nitrogen content of 240ppm, higher than Japan's Sumitomo and Element Six, most likely this study synthetic single crystal growth too fast and lead.

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CLC: > Industrial Technology > Chemical Industry > Electric industry, high - temperature products industry > Production of artificial stones, synthetic stones
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