JpGU-AGU Joint Meeting 2017

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[JJ] Oral

S (Solid Earth Sciences) » S-CG Complex & General

[S-CG73] [JJ] Petrology, Mineralogy and Resource Geology

Mon. May 22, 2017 1:45 PM - 3:15 PM A08 (Tokyo Bay Makuhari Hall)

convener:Satoshi SAITO(Graduate School of Science and Engineering, Ehime University), Koichi Momma(National Museum of Nature and Science), Tatsuo Nozaki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Nobutaka Tsuchiya(Department of Geology, Faculty of Education, Iwate University), Chairperson:Koichi Momma(National Museum of Nature and Science), Chairperson:Satoshi Saito(Graduate School of Science and Engineering, Ehime University)

2:15 PM - 2:30 PM

[SCG73-02] Coloration Analysis of Yellow Synthetic Diamonds

*qianyi zhao1,2 (1.China Univ. of Geosci. (Wuhan), 2.Guangzhou College. SCUT)

Keywords:Synthetic diamond, HTHP, Coloration

Almost all of the high temperature-high pressure (HTHP) synthetic diamonds have yellow tone, which is discussed and solved in this thesis. The yellow synthetic diamond samples are tested with UV – visible light spectrophotometer, micro-infrared spectroscopy, cathode luminescence and other large equipments. We focus on high temperature and high pressure conditions changing, and the following conclusions are made :In the high temperature under vacuum pressure, diamond is not in the stable phase region, graphite can easily occur. Under experimental high temperature and pressure conditions (1500-1600 ℃, 7.50GPa), the color of samples in this thesis have changed, the yellow tone has been obviously decreased, and the experiment is repeatable. Micro-infrared spectroscopy reveals, significant peak intensity and position changes occurred in 1100-1500cm-1 spectral region of nitrogen. UV - visible spectrophotometer test of the samples before and after experiment shows that the color has changed, the samples become light-colored. Synthetic diamonds at HTHP treatment changes occurred in diamond type from IaA + Ib to IaAB + Ib. The band theory can explain the reasons for diamond’s coloration.