非金属触媒からのダイヤモンド合成とその特徴

概要

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Diamond crystales have been synthsized using non-metallic catalysts such as CaCO_3 and Na_2SO_4 instead of metal catalysts under 5.5〜8 GPa and 1600〜2100℃. The crystals have usually several tens μm in diameter. The growth rate was much lower than that of diamond grown from metal catalysts. The growth rate in the <100 > direction was several times higher than that in the <111>. This means that octahedron is a preferred form of the grown crystals. On {111} faces were observed growth hillocks with spiral patterns. {100} faces were undulated and exhibited pyramidal growth hillocks additionally. Hackly {100} faces have also been observed. They consist of numerous pyramidal pits with a few μm to several ten μm in dimension. Cathodoluminescence spectroscopy showed the crystals exhibit three vibronic bands, 575 nm, H3, and N3, which are related to nitrogen, and a broad band with a peak around 430nm. They were storongly localized in the crystal and even on the growth surface.
宝石学会(日本)の論文
1991-07-30