HR: 0800h
AN: GP21A-0116    [Abstracts]
TI: Electron Holography and Magnetic Properties of Exsolved Synthetic Titanomagnetites
AU: * Church, N S
EM: nc315@cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge Downing Street, Cambridge, CB2 3EQ, United Kingdom
AU: Harrison, R J
EM: rjh@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge Downing Street, Cambridge, CB2 3EQ, United Kingdom
AU: Kasama, T
EM: tk305@cam.ac.uk
AF: Department of Materials Science and Metallurgy, University of Cambridge Pembroke Street, Cambridge, CB2 3QZ, United Kingdom
AU: Dunin-Borkowski, R E
EM: red10@hermes.cam.ac.uk
AF: Department of Materials Science and Metallurgy, University of Cambridge Pembroke Street, Cambridge, CB2 3QZ, United Kingdom
AB: Natural titanomagnetites frequently exhibit nano-scale exsolution structures, but the contribution to bulk magnetic properties of these assemblages of iron-rich ferromagnetic titanomagnetites and titanium-rich paramagnetic ilmenite and ulvospinel is poorly understood. To investigate the role of these two-phase systems, a suite of single-phase polycrystalline and single-crystal samples were synthesized from the magnetite-ulvospinel solid solution. They were characterized using magnetic properties and subsequently resintered under oxidizing conditions to create two-phase systems of titanomagnetite and ilmenite. These systems exhibited a variety of geometries depending on the oxygen fugacity and temperature of the oxidizing run, including lamellar exsolution which mimics that found in natural magnetite-ulvospinel assemblages. These exsolved samples were examined using electron holography to quantitatively measure the magnetic flux in and around the magnetic grains and the collective behavior of interacting magnetic grains. A more thorough understanding of these interaction effects and the domain states of the magnetic grains can inform our interpretation of both remanence measurements and bulk rock properties.
DE: 1540 Rock and mineral magnetism
DE: 1594 Instruments and techniques
DE: 3929 NMR, Mossbauer spectroscopy, and other magnetic techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting