Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005geoji.160.1059n&link_type=abstract
Geophysical Journal International, Volume 160, Issue 11, pp. 1059-1067.
Astronomy and Astrophysics
Astronomy
11
Carbon, Electrical Conductivity, Graphitization, Stress, Temperature
Scientific paper
Graphitization of less-ordered hexagonal carbon was studied under in-situ pressure and temperature conditions on anthracite, black shale and a synthetic calcite/anthracite mixture at upper greenschist facies conditions. Anthracite exhibited a continuous loss of volatiles in the temperature range from 100 °C up to 850 °C (9.9 weight per cent at 450 °C) as detected by Differential-Thermal-Analysis (DTA) and Thermo-Gravimetry (TG). Energy dispersive X-ray diffraction (EDX) revealed a broad amorphous 002 graphite reflection while after p, T-treatment nearly perfect crystallized graphitic carbon was detected. The electrical conductivity was measured at the same time in the frequency range from 0.7 up to 100 kHz. As a function of time the bulk resistivity was decreased by about three orders in magnitude at constant pressure and temperature conditions (0.7 GPa, 450 °C), while the complex response exhibited a continuous decrease of the imaginary part of the impedance. `Quasi-metallic' conduction now dominated the charge transport. Application of pressure, strain, temperature and time caused an increase in ordering and the degree of interconnection of the formerly randomly oriented carbon sheets. The experimental results are an approach towards the explanation of the abundant occurrence of crystalline graphite observed in overthrusts and nappe structures, which are distinguished by high-conductivity structures.
Nover Georg
Stoll Johannes B.
von der Gönna Jutta
No associations
LandOfFree
Promotion of graphite formation by tectonic stress - a laboratory experiment does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Promotion of graphite formation by tectonic stress - a laboratory experiment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Promotion of graphite formation by tectonic stress - a laboratory experiment will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1216312