TY - JOUR
T1 - Grain-growth kinetics of ferropericlase at high-pressure
AU - Tsujino, Noriyoshi
AU - Nishihara, Yu
N1 - Funding Information:
The authors thank E. Takahashi for helpful comments, H. Kagi for allowing and helping the authors to use FTIR at Geochemical Laboratory, University of Tokyo, T. Suzuki for help in measurement of grain size, K. Sato for help in preparing the starting material, A. Akashi for help in performing pressure calibration (relation of pressure and load) for Kawai-type multi-anvil press SPI-1000 and P. Bhalla for reading of manuscript. The authors are also grateful to Takahashi-laboratory members. Official review by three anonymous reviewers improved the quality of the manuscript. This work was supported by Grant-in-aid for Young Scientists (B) (No. 17740348) to YN, Grant-in-aid No. 18204050 to E. Takahashi and 21st century COE Program of the Japan Society of the Promotion of Science.
PY - 2009/5
Y1 - 2009/5
N2 - Grain-growth kinetics of (Mg0.85Fe0.15)O ferropericlase was investigated at pressures of 5 and 10 GPa and temperatures of 1673-1873 K using a Kawai-type multi-anvil apparatus. Presintered ferropericlase aggregate with an average grain size of 4.0 μm was used as starting material of grain-growth annealing experiments. The grain-growth kinetics of ferropericlase is described by Gn - G0n = k0 t exp [ - (E* + P V*) / R T ], where G is the average grain size at annealing time t, G0 the initial average grain size, P the pressure, R the gas constant and T is the absolute temperature, with n = 2.6 ± 0.4, log10 k0 = -7.5 ± 1.7 m2.6/s, E* = 262 ± 30 kJ/mol, V* = 4.7 ± 0.7 cm3/mol. Compared at same pressure and temperature, grain-growth rate of ferropericlase is similar to olivine and faster than those of wadsleyite and ringwoodite. The present results show that, at the top of the lower mantle (P = 25 GPa and T = 1773 K) grain size of ferropericlase in single phase system evolves to ∼2 × 10-2 m after significant geological time (10 My) while a previous study predicts that grain size of MgO in two-phase system is as small as ∼8 × 10-6 m at same condition.
AB - Grain-growth kinetics of (Mg0.85Fe0.15)O ferropericlase was investigated at pressures of 5 and 10 GPa and temperatures of 1673-1873 K using a Kawai-type multi-anvil apparatus. Presintered ferropericlase aggregate with an average grain size of 4.0 μm was used as starting material of grain-growth annealing experiments. The grain-growth kinetics of ferropericlase is described by Gn - G0n = k0 t exp [ - (E* + P V*) / R T ], where G is the average grain size at annealing time t, G0 the initial average grain size, P the pressure, R the gas constant and T is the absolute temperature, with n = 2.6 ± 0.4, log10 k0 = -7.5 ± 1.7 m2.6/s, E* = 262 ± 30 kJ/mol, V* = 4.7 ± 0.7 cm3/mol. Compared at same pressure and temperature, grain-growth rate of ferropericlase is similar to olivine and faster than those of wadsleyite and ringwoodite. The present results show that, at the top of the lower mantle (P = 25 GPa and T = 1773 K) grain size of ferropericlase in single phase system evolves to ∼2 × 10-2 m after significant geological time (10 My) while a previous study predicts that grain size of MgO in two-phase system is as small as ∼8 × 10-6 m at same condition.
KW - Annealing
KW - Ferropericlase
KW - Grain growth
KW - Grain size
KW - High-pressure
KW - Lower mantle
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U2 - 10.1016/j.pepi.2008.04.002
DO - 10.1016/j.pepi.2008.04.002
M3 - Article
AN - SCOPUS:67349245957
VL - 174
SP - 145
EP - 152
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
SN - 0031-9201
IS - 1-4
ER -