Reactions between carbon and a reduced C-O-H fluid under diamond-stable HP-HT condition

Citation
M. Akaishi et al., Reactions between carbon and a reduced C-O-H fluid under diamond-stable HP-HT condition, DIAM RELAT, 10(12), 2001, pp. 2125-2130
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
DIAMOND AND RELATED MATERIALS
ISSN journal
0925-9635 → ACNP
Volume
10
Issue
12
Year of publication
2001
Pages
2125 - 2130
Database
ISI
SICI code
0925-9635(200112)10:12<2125:RBCAAR>2.0.ZU;2-Z
Abstract
Reactions between graphitic carbon and a reduced C-O-H fluid were investiga ted using a mixture of stearic acid C18H36O2 and oxalic acid dihydrate C2H6 O6, as the fluid source at high pressure and temperature (HP-HT) of 7.7 GPa and 1500 degreesC in a platinum sealed capsule. A reduced C-O-H fluid main ly composed of methane and water, was formed by the thermal decomposition o f the fluid source before reaching the HP-HT condition. An exchange reactio n between carbon and methane occurred and starting carbon was re-crystalliz ed to flaky graphite crystals, but no diamond was formed for the duration u p to 24 h. In the experiment for 48 h, octahedral diamond crystals of a few to a few tens of micrometers in size were observed along with the recrysta llized graphite. These results show that reduced C-O-H fluid acts as a diam ond forming catalyst, although a long incubation time is necessary for diam ond formation. (C) 2001 Elsevier Science B.V. All rights reserved.