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Title: Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C

Abstract

Acoustic wave velocities for synthetic polycrystalline pyrope (Mg{sub 3}Al{sub 2}Si{sub 3}O{sub 12}) were measured to 9 GPa and temperatures up to 1000 degrees C by ultrasonic interferometry combined with energy-dispersive synchrotron X-ray diffraction in a cubic-anvil DIA-type apparatus (SAM-85). Specimen lengths at high pressures (P) and temperatures (T) are directly measured by X-radiographic methods. Elastic wave travel times and X-ray diffraction data were collected after heating and cooling at high pressures to minimize effect of non-hydrostatic stress on the measurements. A linear fit to the high P and T data set yields the elastic bulk and shear moduli [K{sub S} = 175 (2) GPa; G = 91 (1) GPa] and their pressure and temperature derivatives [K{prime}{sub S}=3.9{+-}0.3; G{prime} = 1.7 {+-} 0.2 and ({partial_derivative}K{sub S}/{partial_derivative}T){sub P} = -18 (2) MPa/K; ({partial_derivative}G/{partial_derivative}T){sub P} = -10 (1) MPa/K]. In a separate analysis, the pressure-volume-temperature data collected during these acoustic experiments were fit to a high temperature Birch-Murnaghan (HTBM) equation [with K{prime} fixed at 3.9] and to each isothermal P-V-T data yielding ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -22 (2) MPa/K and ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -20 (5) MPa/K, respectively. Comparison of Py{sub 100} data with those other Py-Mj compositions indicates that the thermo elasticmore » properties are insensitive to majorite content in the garnet along the pyrope-majorite join.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
914167
Report Number(s):
BNL-78735-2007-JA
Journal ID: ISSN 0031-9201; PEPIAM; TRN: US0801589
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Earth Planet. Interiors; Journal Volume: 155; Journal Issue: 3-4
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACOUSTICS; ELASTICITY; GARNETS; HEATING; INTERFEROMETRY; SHEAR; SYNCHROTRONS; ULTRASONIC WAVES; X-RAY DIFFRACTION; national synchrotron light source

Citation Formats

Gwanmesia,G., Zhang, J., Darling, K., Kung, J., Li, B., Wang, L., Neuville, D., and Liebermann, R.. Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C. United States: N. p., 2006. Web. doi:10.1016/j.pepi.2005.10.008.
Gwanmesia,G., Zhang, J., Darling, K., Kung, J., Li, B., Wang, L., Neuville, D., & Liebermann, R.. Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C. United States. doi:10.1016/j.pepi.2005.10.008.
Gwanmesia,G., Zhang, J., Darling, K., Kung, J., Li, B., Wang, L., Neuville, D., and Liebermann, R.. Sun . "Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C". United States. doi:10.1016/j.pepi.2005.10.008.
@article{osti_914167,
title = {Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C},
author = {Gwanmesia,G. and Zhang, J. and Darling, K. and Kung, J. and Li, B. and Wang, L. and Neuville, D. and Liebermann, R.},
abstractNote = {Acoustic wave velocities for synthetic polycrystalline pyrope (Mg{sub 3}Al{sub 2}Si{sub 3}O{sub 12}) were measured to 9 GPa and temperatures up to 1000 degrees C by ultrasonic interferometry combined with energy-dispersive synchrotron X-ray diffraction in a cubic-anvil DIA-type apparatus (SAM-85). Specimen lengths at high pressures (P) and temperatures (T) are directly measured by X-radiographic methods. Elastic wave travel times and X-ray diffraction data were collected after heating and cooling at high pressures to minimize effect of non-hydrostatic stress on the measurements. A linear fit to the high P and T data set yields the elastic bulk and shear moduli [K{sub S} = 175 (2) GPa; G = 91 (1) GPa] and their pressure and temperature derivatives [K{prime}{sub S}=3.9{+-}0.3; G{prime} = 1.7 {+-} 0.2 and ({partial_derivative}K{sub S}/{partial_derivative}T){sub P} = -18 (2) MPa/K; ({partial_derivative}G/{partial_derivative}T){sub P} = -10 (1) MPa/K]. In a separate analysis, the pressure-volume-temperature data collected during these acoustic experiments were fit to a high temperature Birch-Murnaghan (HTBM) equation [with K{prime} fixed at 3.9] and to each isothermal P-V-T data yielding ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -22 (2) MPa/K and ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -20 (5) MPa/K, respectively. Comparison of Py{sub 100} data with those other Py-Mj compositions indicates that the thermo elastic properties are insensitive to majorite content in the garnet along the pyrope-majorite join.},
doi = {10.1016/j.pepi.2005.10.008},
journal = {Phys. Earth Planet. Interiors},
number = 3-4,
volume = 155,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Acoustic wave velocities for synthetic polycrystalline pyrope (Mg3Al2Si3O12) were measured to 9 GPa and temperatures up to 1000 C by ultrasonic interferometry combined with energy-dispersive synchrotron X-ray diffraction in a cubic-anvil DIA-type apparatus (SAM-85). Specimen lengths at high pressures (P) and temperatures (T) are directly measured by X-radiographic methods. Elastic wave travel times and X-ray diffraction data were collected after heating and cooling at high pressures to minimize effect of non-hydrostatic stress on the measurements. A linear fit to the high P and T data set yields the elastic bulk and shear moduli [KS = 175 (2) GPa; G =more » 91 (1) GPa] and their pressure and temperature derivatives [K'S=3.9{+-}0.3; G' = 1.7 {+-} 0.2 and ({partial_derivative}KS/{partial_derivative}T)P = -18 (2) MPa/K; ({partial_derivative}G/{partial_derivative}T)P = -10 (1) MPa/K]. In a separate analysis, the pressure-volume-temperature data collected during these acoustic experiments were fit to a high temperature Birch-Murnaghan (HTBM) equation [with K' fixed at 3.9] and to each isothermal P-V-T data yielding ({partial_derivative}KT/{partial_derivative}T)P = -22 (2) MPa/K and ({partial_derivative}KT/{partial_derivative}T)P = -20 (5) MPa/K, respectively. Comparison of Py100 data with those other Py-Mj compositions indicates that the thermo elastic properties are insensitive to majorite content in the garnet along the pyrope-majorite join.« less
  • Magnesium grain boundary diffusion rates in forsterite aggregates have been experimentally determined from 1000{degrees} to 1300{degrees}C and 0.1 MPa to 10 GPa. The samples are fine-grained (mean linear intercept of 4.3 {mu}m) hot-pressed aggregates. The technique employs a {sup 26}Mg-enriched surface layer and depth profiling using an ion microprobe. Values of the product of the grain boundary diffusion coefficient (D{prime}) and the effective grain boundary width ({delta}) were calculated using appropriate analytical solutions to the grain boundary diffusion equation of Whipple. The Arrhenius parameters for the 0.1 MPa data for samples annealed in H{sub 2}+CO{sub 2} and CO+CO{sub 2} gasmore » mixtures are D{sub 0}{prime}{delta} = 2.1 {times} 10{sup {minus}10} and 7.7 {times} 10{sup {minus}10} m{sup 3}/s and Q = 343{+-}27 and 376{+-}47 kJ/mol, respectively. The reproducibility of D{prime}{delta} measurements is a factor of 2. A determination of D{prime} independent of {delta} yields a calculated effective grain boundary width of {approximately}3 nm, similar to the physical grain boundary width of 1-3 nm estimated from high-resolution transmission electron microscopy observations. The data indicate a very low pressure dependence from magnesium grain boundary diffusion in forsterite with an apparent activation volume for grain boundary diffusion of {<=}{approximately}1 cm{sup 3}/mol at 1100{degrees}C. The results of this study provide information concerning diffusion creep in solid state deformation of forsterite aggregates over a broad range of pressures and temperatures. 43 refs., 7 figs., 1 tab.« less