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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS001 Oral Presentation 1722
The transition from elastic to viscoelastic behaviour: grain-size sensitive
relaxation in polycrystalline MgO
Dr. Auke Barnhoorn
Research School of Earth Sciences Australian National University IASPEI
John D. Fitz Gerald, Akira Kishimoto
Strictly elastic behaviour gives way at sufficiently high temperatures and long periods to viscoelastic
behaviour manifest in reduced seismic wave speeds and associated attenuation. In order to further
explore the nature of this transitional mechanical behaviour, we have performed seismic-frequency
forced-oscillation experiments at high temperatures on a suite of newly prepared MgO polycrystals (of
high purity and low porosity). The samples were fabricated from powders of 50 nm grain size with
temperature-time trajectories varied to allow different amounts of grain growth resulting in samples
with stable average grain sizes of