| 갈색 Type I 다이아몬드의 고압 열처리에 따른 표면 흑연화 생성 연구 |
| 송정호, 송오성 |
| 서울시립대학교 신소재공학과 |
| Surface Graphite Formation of the Brown Colored Type I Diamonds During High Pressure Annealing |
| Jeongho Song, Ohsung Song |
| Department of Materials Science and Engineering, University of Seoul |
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| ABSTRACT |
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We investigated color and graphite layer formation on the surface of Type I tinted brown diamonds exposed for 5 minutes under a high-pressure high-temperature (HPHT) condition in a stable graphite regime. We executed the HPHT processes of Process I, varying the temperature from $1600^{circ}C$ to $2300^{circ}C$ under 5.2 GPa pressure for 5 minutes, and Process II, varying the pressure from 4.2 to 5.7 GPa at $2150^{circ}C$ for 5 minutes. Optical microscopy and micro-Raman spectroscopy were used to check the microstructure and surface layer phase evolution. For Process I, we observed a color change to vivid yellow and greenish yellow and the growth of a graphite layer as the temperature increased. For Process II, the graphite layer thickness increased as the pressure decreased. We also confirmed by 531 nm micro-Raman spectroscopy that all diamonds showed a $1440cm^{-1}$ characteristic peak, which remained even after HPHT annealing. The results implied that HPHT-treated colored diamonds can be distinguished from natural stones by checking for the existence of the $1440cm^{-1}$ peak with 531 nm micro-Raman spectroscopy. |
| Key words:
Graphite layer, HPHT treated, Type I diamond, Tinted brown colored diamond, Raman spectroscopy |
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