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P-V-T equation of state and high-pressure behavior of CaCO (sub 3) aragonite

Ying Li, Yongtao Zou, Ting Chen, Xuebing Wang, Xintong Qi, Haiyan Chen, Jianguo Du and Baosheng Li
P-V-T equation of state and high-pressure behavior of CaCO (sub 3) aragonite
American Mineralogist (October 2015) 100 (10): 2323-2329


The equation of state of aragonite was determined by in situ synchrotron X-ray diffraction experiments on a hot-pressed polycrystalline specimen of aragonite within its stability field up to 5.8 GPa and 1173 K. As a complement to this experimental study, first-principle density functional theory calculations were performed up to 20 GPa at 0 K. Thermoelastic parameters for aragonite (CaCO (sub 3) ) were derived by a least-squares fit of the experimental P-V-T data to the third-order Birch-Murnaghan equation of state (EOS), yielding the bulk modulus and its pressure and temperature derivatives K (sub 0) =65.24+ or -0.24 GPa, K' (sub 0) =4.95+ or -0.12, (delta K (sub T) /delta (sub T) ) (sub rho ) =-0.002 GPa/K and volume thermal expansion alpha (super 300) =(6.1+ or -0.7)X10 (super -5) K (super -1) . The analyses of the axial compressibility at ambient temperature show that the c-axis is much more compressible than the a- and b-axes. Based on first-principle calculations, the anisotropic compression behavior of aragonite structure is explained by the heterogenous shortening <Ca-O> and <C-O> bond lengths and the rotation of <O-C-O> angles along the a-, b-, and c-axes, whereas the unit-cell volume change of aragonite under compression is accommodated by comparable compression rate of the CaO (sub 9) polyhedra and the voids in the crystal lattice. The results attained from this study provide important thermoelastic parameters for understanding the thermodynamic behavior and chemical reactions involving aragonite at subduction zone conditions.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 100
Serial Issue: 10
Title: P-V-T equation of state and high-pressure behavior of CaCO (sub 3) aragonite
Affiliation: Stony Brook University, Mineral Physics Institute, Stony Brook, NY, United States
Pages: 2323-2329
Published: 201510
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 49
Accession Number: 2016-007315
Categories: Geophysics of minerals and rocks
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201604
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