Fig 10 - uploaded by Yoshiaki Kashiwaya
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Result of observation by laser microscope before and after experiment under 30 vol%CO 2-Ar at 1273 K, 10 min (EXP-3).
Source publication
Recently. a property of diamond as a semiconductor is focused oil by many researchers. For the mass production, it is important to develop the manufacturing process. As it is thought that the ionic milling process has limitations. the application of gasification reactions with oxidizing gases such as CO2, H2O and O-2 is the best option. In this stu...
Contexts in source publication
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... experimen- tal conditions of 'Exp-3' and 'Exp-4' are also shown in Before exp. Figure 10 shows the observation results provided by the laser microscope, which were carried out at 1273 K (Exp-3). The surface of the diamond changed significantly after experiment at 1273 K in comparison with the result of the experiment at low oxygen potential. ...
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... oxygen potential. However, the weight change was very small -about 2 mg-and the reaction degree was 0.1%. On the other hand, the weight change could not be detected in Exp-1 and Exp-2. In Exp-3, the number of small pits increased after the experiment throughout the whole sample surface. When three defects marked (1), (2) and (3) with arrows in Figs. 10(a) and (c) were focused upon, they showed completely different behaviors. Defects (1) and (2) became especially large and turned white after the experi- ment (Fig. 10(b)). When these positions were examined by Raman spectroscopic measurements, only the peak corre- sponding to diamond was detected, while the other position showed the A ...
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... in Exp-1 and Exp-2. In Exp-3, the number of small pits increased after the experiment throughout the whole sample surface. When three defects marked (1), (2) and (3) with arrows in Figs. 10(a) and (c) were focused upon, they showed completely different behaviors. Defects (1) and (2) became especially large and turned white after the experi- ment (Fig. 10(b)). When these positions were examined by Raman spectroscopic measurements, only the peak corre- sponding to diamond was detected, while the other position showed the A band and G band, corresponding to the amorphous and graphite structures. On the other hand, it was found that the defect of the triangle as shown by (3) did not largely ...
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Diamond is the ultimate state of carbon crystal. However, a transformation from diamond to graphite during gasification occurs under oxidizing atmosphere. The gasification behaviors of diamond vary with the reaction gas composition and temperature. There has been no kinetic study oil the diamond gasification. Most of the interest in this area has b...
Citations
... The crystallographic orientation between the diamond and the formed graphite was presented in the previous study. 8) As mentioned above, there have been many studies on the gasification of various kinds of carbon. However, no gas- ification study has been conducted for the diamond. ...
Diamond is the ultimate state of carbon crystal. However, a transformation from diamond to graphite during gasification occurs under oxidizing atmosphere. The gasification behaviors of diamond vary with the reaction gas composition and temperature. There has been no kinetic study oil the diamond gasification. Most of the interest in this area has been related to diamond growth. The change of morphology of diamond surface and the crystallographic orientation between the diamond and the graphite formed was presented in a previous study. In this study. the gasification Of natural diamond was investigated using TG-DTA. Kinetic analysis was performed on the basis of Langmuir-Hinshelwood type equation. in which some rate constant was modified from the previous study for coke gasification. SEM observations of the diamond surface were carried out in order to clarify the change in surface morphology. Moreover, the simultaneous gasification of diamond and graphite was carried out in order to clarify the difference in reactivity between ordinary graphite and graphite formed on the diamond during gasification.
