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P‐V‐T relations of MgSiO 3 perovskite determined by in situ X‐ray diffraction using a large‐volume high‐pressure apparatus
Author(s) -
Katsura Tomoo,
Yokoshi Sho,
Kawabe Kazuaki,
Shatskiy Anton,
Manthilake M. A. Geeth M.,
Zhai Shuangmeng,
Fukui Hiroshi,
Hegoda H. A. Chamathni I.,
Yoshino Takashi,
Yamazaki Daisuke,
Matsuzaki Takuya,
Yoneda Akira,
Ito Eiji,
Sugita Mitsuhiro,
Tomioka Naotaka,
Hagiya Kenji,
Nozawa Akifumi,
Funakoshi Kenichi
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl035658
Subject(s) - volume (thermodynamics) , in situ , diffraction , perovskite (structure) , materials science , x ray crystallography , compositional data , mineralogy , geology , thermodynamics , analytical chemistry (journal) , crystallography , chemistry , physics , mathematics , optics , meteorology , statistics , environmental chemistry
The volume of MgSiO 3 perovskite has been precisely measured at pressures of 19 to 53 GPa and temperatures of 300 to 2300 K by means of in situ X‐ray diffraction in a multi‐anvil apparatus. The present results indicate the isothermal bulk modulus K T0 = 256(2) GPa and its pressure derivative K ′ T0 = 3.8(2). The fixed Debye temperature θ 0 = 1030 K gives a Grüneisen parameter at ambient pressure γ 0 = 2.6(1) and its logarithmic volume dependence q = 1.7(1). The pressure derivative of the isothermal bulk modulus, Anderson‐Grüneisen parameter and thermal expansion coefficient at ambient pressure are found to be (∂ K T /∂ T ) P = −0.035(2) GPa/K, δ T = 6.5(5), α 0 = 2.6(1) × 10 −5 + 1.0(1) × 10 −8 ( T − 300)/K. Thus the thermal expansion coefficient largely becomes smaller with increasing pressure. The adiabatic geotherm would be fairly large, such as 0.41 K/km at a 660 km depth, and becoming smaller with increasing depth. The temperature and adiabatic geothermal gradient at the bottom of the D′ layer would be 2400 K and 0.14 K/km. The buoyancy‐driven mantle convection could be very small in the lower part of the lower mantle.