11:45 AM - 12:00 PM
[SSS06-10] Graphene oxide in the Mozumi-Sukenobe fault of the Atotsugawa fault system: Effects on mechanical and electromagnetic properties
Keywords:Graphene oxide, Creep, Atotsugawa fault system, Mozumi-Sukenobe fault, Graphite, Raman spectroscopy
The Atotsugawa fault system is the only creeping active fault in Japan (Hirahara et al., 2003). Graphite attracts attention as a factor for the creeping movement because it has a low friction coefficient regardless of slip rate (Oohashi et al., 2011, 2012). Since graphite consists of stacked layers of graphene, graphene might be present in faults. Therefore, in this study we focused on graphene oxide (GO), a material with oxygen-containing functional groups and defects. Because graphene changes its properties depending on redox conditions and its shape, it is necessary to reconsider how GO affects faults. Therefore, in this study, by detailed Raman spectroscopy, we reported the discovery of the presence of GO in the fracture zone of the Mozumi-Sukenobe fault in the Atotsugawa fault system for the first time in the world and discussed how GO affects the fault properties.
The Mozumi-Sukenobe fault is located in the Tedori Group of the Hida belt , and two prominent fracture zones are identified (Tanaka et al., 2006). The samples were collected from the fault gouge of the B fracture zone (southern side) of the active fault survey tunnel. Particles of several millimeters from the sample were impregnated with epoxy, and the surface was polished. The sample was measured by Raman spectroscopy, followed by SEM observation and EDS analysis. We used the quantitative classification of GO by King et al. (2016) and identified graphene oxide. The difference of Raman shift between the apparent G peak at ~1600cm-1 (Gapp) and the inferred D' peak (D'inf) by halving the Raman shift of the 2D' peak provides the information of GO. Based on this, we quantitatively classify the graphene materials into GO, reduced graphene oxide (rGO) and graphite.
Raman spectroscopy revealed that many measurement points were GO. Because there is a correlation between the Raman shifts of the D4 and D3 peaks and the oxygen content of GO (Claramunt et al., 2015), we estimated the oxygen content of GO to be 10~20 % in the sample. In addition, SEM observations showed that the gouge was characterized by layered fractures due to adhesive wear.
From Raman spectroscopic analysis, we discovered the presence of GO in the Mozumi-Sukenobe fault for the first time. The friction coefficient of GO is reported to be ~0.01 (Bouchet et al., 2017), which is one order of magnitude lower than that of graphite. Therefore, GO can reduce the frictional strength of the fault more effectively than graphite. In addition, because the electrical conductivity of GO is inversely proportional to the oxygen content (Morimoto, 2016), the electrical conductivity of GO in the sample can be estimated as 103~105 S/m. This is equal to that of graphite, so GO can also be an electric conductor and influences seismio-electromagnetic phenomena.
The Mozumi-Sukenobe fault is located in the Tedori Group of the Hida belt , and two prominent fracture zones are identified (Tanaka et al., 2006). The samples were collected from the fault gouge of the B fracture zone (southern side) of the active fault survey tunnel. Particles of several millimeters from the sample were impregnated with epoxy, and the surface was polished. The sample was measured by Raman spectroscopy, followed by SEM observation and EDS analysis. We used the quantitative classification of GO by King et al. (2016) and identified graphene oxide. The difference of Raman shift between the apparent G peak at ~1600cm-1 (Gapp) and the inferred D' peak (D'inf) by halving the Raman shift of the 2D' peak provides the information of GO. Based on this, we quantitatively classify the graphene materials into GO, reduced graphene oxide (rGO) and graphite.
Raman spectroscopy revealed that many measurement points were GO. Because there is a correlation between the Raman shifts of the D4 and D3 peaks and the oxygen content of GO (Claramunt et al., 2015), we estimated the oxygen content of GO to be 10~20 % in the sample. In addition, SEM observations showed that the gouge was characterized by layered fractures due to adhesive wear.
From Raman spectroscopic analysis, we discovered the presence of GO in the Mozumi-Sukenobe fault for the first time. The friction coefficient of GO is reported to be ~0.01 (Bouchet et al., 2017), which is one order of magnitude lower than that of graphite. Therefore, GO can reduce the frictional strength of the fault more effectively than graphite. In addition, because the electrical conductivity of GO is inversely proportional to the oxygen content (Morimoto, 2016), the electrical conductivity of GO in the sample can be estimated as 103~105 S/m. This is equal to that of graphite, so GO can also be an electric conductor and influences seismio-electromagnetic phenomena.