HR: 0800h
AN: T51B-1336    [Abstracts]
TI: Positive charge carriers flowing out of partially stressed synthetic quartz: a fundamental experiment for modeling seismo-electromagnetic phenomena
AU: * Takeuchi, A
EM: takeuchi@curie.sc.niigata-u.ac.jp
AF: Niigata University, Department of Chemistry, 8050 Ikarashi-ninocho, Niigata, 950-2181 Japan
AU: * Takeuchi, A
EM: takeuchi@curie.sc.niigata-u.ac.jp
AF: San Jose State University, Department of Physics, One Washington Square, San Jose, 95192-0106 United States
AU: Lau, B W
EM: bwslau@hotmail.com
AF: San Jose State University, Department of Physics, One Washington Square, San Jose, 95192-0106 United States
AU: da Silva, M S
EM: massilva@fc.up.pt
AF: Universidade do Porto, Departmento de Física, Rua do Campo Alegre, 687, Porto, 4169-007 Portugal
AU: Freund, F T
EM: ffreund@core2.gsfc.nasa.gov
AF: San Jose State University, Department of Physics, One Washington Square, San Jose, 95192-0106 United States
AU: Freund, F T
EM: ffreund@core2.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Code 698, Greenbelt, MD 20771 United States
AB: To understand abnormal telluric currents in the EarthOs crust before and during major earthquakes, we focus on one specific defect, probably abundant in minerals in common igneous rocks. This defect is a peroxy link, also known as positive hole pair (PHP). Stress can activate the O-O link allowing an electron from a neighboring oxygen anion to jump onto the broken O-O link. Thereby, the neighboring oxygen anion changes its valence from -2 to -1 and becomes a positive hole (p-hole). The p-hole can spread as an electronic state (a defect electron) through the oxygen anion sublatice, constituting an electric current. Quartz is a common mineral in many igneous rocks. We measured currents flowing out of stressed portions of synthetic quartz. The samples were (i) single crystal bars, 10 x 10 x 112 mm{³} in size, and (ii) Y-cut slices, 30 x 60 x (2-27) mm{³} in size. One of the slices was irradiated with 5 kGy of gamma. The currents produced under partial stress as a function of loading cannot be solely explained by piezoelectric effects but point to the stress-activation of pre-existing PHPs and the generation of p-hole charge carriers.
DE: 3902 Creep and deformation
DE: 3904 Defects
DE: 3914 Electrical properties
DE: 5109 Magnetic and electrical properties (0925)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Tectonophysics [T]
MN: Fall Meeting 2005