HR: 1340h
AN: MR13C-1403    [Abstracts]
TI: Analysis of micro-fabricated, controlled geometry samples for determination of material transport properties of core materials
AU: * Reaman, D M
EM: reaman.5@geology.ohio-state.edu
AF: The Ohio State University, Dept. of Geological Sciences, 275 Mendenhall Lab, 125 S oval Mall, Columbus, OH 43210, United States
AU: Panero, W R
EM: panero.1@geology.ohio-state.edu
AF: The Ohio State University, Dept. of Geological Sciences, 275 Mendenhall Lab, 125 S oval Mall, Columbus, OH 43210, United States
AB: Chemical diffusion rates in iron and nickel provide key constraints on the behavior of planetary core materials. Samples were created for use in the laser-heated or externally-heated diamond anvil cell by sputtering 300 nm of Ni onto the surface of a 10-micron thick Fe64Ni36 alloy foil under ultra-high vacuum, after ion-etching to remove surface oxidation. Samples heated under pressure up to 1200 K show that a depth profile through the sample using secondary ionization mass spectrometry (SIMS) can accurately constrain the diffusivity of iron and nickel in these samples. Diffusivities over 10-19 m2/s can be determined with 0.1 log unit accuracy. Initial experiments at 1063K give a diffusivity of 1.2x10-17 m2/s, consistent with Yunker and van Orman (2004). Issues of the pressure medium, initial surface roughness, and knock-on effects will also be discussed. The diffusivity of hcp iron and iron-nickel alloys as determined in the laser-heated diamond anvil cell can be used to infer the solid-state viscosity of the inner-core, which may govern the mechanism to develop inner-core anisotropy.
DE: 3924 High-pressure behavior
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting