Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi3 O8)

Mainak Mookherjee; David Mainprice; Ketan Maheshwari; Olle Heinonen; Dhenu Patel; Anant Hariharan

doi:10.1038/srep34815

Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi₃ O₈)

Mainak Mookherjee, David Mainprice, Ketan Maheshwari, Olle Heinonen, Dhenu Patel, Anant Hariharan

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23 Scopus citations

Abstract

Albite (NaAlSi₃ O₈) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6-8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts. At pressure <6 GPa, the PAW-GGA can be described by a Birch-Murnaghan equation of state with V₀^GGA= 687.4 Å³,K₀^GGA= 51.7 GPa, and K₀^'GGA= 4.7. The shear modulus and its pressure derivative are G₀^GGA= 33.7 GPa, and G₀^'GGA= 2.9. At 1 bar, the azimuthal compressional and shear wave anisotropy AV_P^GGA = 42.8%, and AV_S^GGA= 50.1%. We also investigate the densification of albite to a mixture of jadeite and quartz. The transformation is likely to cause a discontinuity in density, compressional, and shear wave velocity across the crust and mantle. This could partially account for the Mohorovicic discontinuity in thickened continental crustal regions.

Original language	English
Article number	34815
Journal	Scientific Reports
Volume	6
DOIs	https://doi.org/10.1038/srep34815
State	Published - Oct 13 2016
Externally published	Yes

Funding

M.M. is currently supported by US-NSF EAR-1634422. M.M. and K.M. acknowledges computing resources from ALCF Mira Supercomputer through grant "ElasticEarthCrust". The work by O.H. was supported in part by the US DOE, Office of Science under Contract No. DE-AC02-06CH11357. Authors thank the reviewers and associate editor for their constructive criticism that helped to enhance the clarity of the manuscript.

Funders	Funder number
US-NSF	EAR-1634422
National Science Foundation	1634422
U.S. Department of Energy
Office of Science	DE-AC02-06CH11357
Bonnie J. Addario Lung Cancer Foundation

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title = "Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi3 O8)",

abstract = "Albite (NaAlSi3 O8) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6-8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts. At pressure <6 GPa, the PAW-GGA can be described by a Birch-Murnaghan equation of state with V0GGA= 687.4 {\AA}3,K0GGA= 51.7 GPa, and K0'GGA= 4.7. The shear modulus and its pressure derivative are G0GGA= 33.7 GPa, and G0'GGA= 2.9. At 1 bar, the azimuthal compressional and shear wave anisotropy AVPGGA = 42.8%, and AVSGGA= 50.1%. We also investigate the densification of albite to a mixture of jadeite and quartz. The transformation is likely to cause a discontinuity in density, compressional, and shear wave velocity across the crust and mantle. This could partially account for the Mohorovicic discontinuity in thickened continental crustal regions.",

author = "Mainak Mookherjee and David Mainprice and Ketan Maheshwari and Olle Heinonen and Dhenu Patel and Anant Hariharan",

year = "2016",

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doi = "10.1038/srep34815",

language = "English",

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journal = "Scientific Reports",

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T1 - Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi3 O8)

AU - Mookherjee, Mainak

AU - Mainprice, David

AU - Maheshwari, Ketan

AU - Heinonen, Olle

AU - Patel, Dhenu

AU - Hariharan, Anant

PY - 2016/10/13

Y1 - 2016/10/13

N2 - Albite (NaAlSi3 O8) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6-8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts. At pressure <6 GPa, the PAW-GGA can be described by a Birch-Murnaghan equation of state with V0GGA= 687.4 Å3,K0GGA= 51.7 GPa, and K0'GGA= 4.7. The shear modulus and its pressure derivative are G0GGA= 33.7 GPa, and G0'GGA= 2.9. At 1 bar, the azimuthal compressional and shear wave anisotropy AVPGGA = 42.8%, and AVSGGA= 50.1%. We also investigate the densification of albite to a mixture of jadeite and quartz. The transformation is likely to cause a discontinuity in density, compressional, and shear wave velocity across the crust and mantle. This could partially account for the Mohorovicic discontinuity in thickened continental crustal regions.

AB - Albite (NaAlSi3 O8) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6-8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts. At pressure <6 GPa, the PAW-GGA can be described by a Birch-Murnaghan equation of state with V0GGA= 687.4 Å3,K0GGA= 51.7 GPa, and K0'GGA= 4.7. The shear modulus and its pressure derivative are G0GGA= 33.7 GPa, and G0'GGA= 2.9. At 1 bar, the azimuthal compressional and shear wave anisotropy AVPGGA = 42.8%, and AVSGGA= 50.1%. We also investigate the densification of albite to a mixture of jadeite and quartz. The transformation is likely to cause a discontinuity in density, compressional, and shear wave velocity across the crust and mantle. This could partially account for the Mohorovicic discontinuity in thickened continental crustal regions.

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ER -

Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi₃ O₈)

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