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182 results on '"van den Berg, Arie P."'

6. Thermodynamic properties of geikielite (MgTiO3) and ilmenite (FeTiO3) derived from vibrational methods combined with Raman and infrared spectroscopic data

Author

Jacobs, Michael H.G., van den Berg, Arie P., Schmid-Fetzer, Rainer, de Vries, Jellie, van Westrenen, Wim, Zhao, Yue, Jacobs, Michael H.G., van den Berg, Arie P., Schmid-Fetzer, Rainer, de Vries, Jellie, van Westrenen, Wim, and Zhao, Yue

Abstract

We present a model for the lattice vibrational density of states of MgTiO3 (geikielite) and FeTiO3 (ilmenite) that predicts thermodynamic properties, in agreement with observational data. The model is based on Kieffer’s method combined with spectroscopic data. For both substances experimental data sets are influenced by non-stoichiometry. For geikielite that affects the volume, whereas for ilmenite volume and bulk modulus are affected. We show that Kieffer’s method enables predicting bulk moduli in pressure–temperature space. We demonstrate that intrinsic anharmonicity or electronic effects significantly affect the heat capacity of ilmenite, whereas that is not the case for geikielite. We use Kieffer’s method to derive multiple-Einstein models, from which we demonstrate that thermodynamic properties are insignificantly influenced by dispersion in Grüneisen, mode-q and anharmonicity parameters for both substances. We show that our results enable predicting thermodynamic properties and shear modulus of the solid solution formed from geikielite and ilmenite. Geikielite and ilmenite are added to our thermodynamic database for the system MgO–SiO2–FeO, to enable modeling phase stability and physical properties of titanium-rich reservoirs in the Earth’s Moon.

Published
2022
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10. Thermophysical properties and phase diagrams in the system MgO–SiO 2 –FeO at upper mantle and transition zone conditions derived from a multiple-Einstein method

Author

Jacobs, Michael H.G., Schmid-Fetzer, Rainer, van den Berg, Arie P., Mantle dynamics & theoretical geophysics, Geology and Geochemistry, and Mantle dynamics & theoretical geophysics

Subjects
Phase boundary, 010504 meteorology & atmospheric sciences, Thermodynamics, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Heat capacity, Pressure scale, Materials Science(all), Geochemistry and Petrology, Vibrational density of states, Coesite, Transition zone, General Materials Science, SDG 7 - Affordable and Clean Energy, 0105 earth and related environmental sciences, Phase diagram, Equation of state, Chemistry, Anharmonicity, Atmospheric temperature range, Elasticity, Ringwoodite, engineering, Ferropericlase
Abstract

We applied a lattice vibrational technique, based on representing the vibrational density of states with multiple-Einstein frequencies, to determine consistency of data on thermophysical properties and phase diagrams in the system MgO–FeO–SiO 2 . We present analyses of these data in the temperature range between 0 and 2000 K and pressure range between 0 and 20 GPa. The result is a database containing phases relevant to the Earth upper mantle and transition zone. We show that consistency of different datasets associated with the dissociation of the ringwoodite form of Fe 2 SiO 4 depends on the crucible material that has been used to perform partitioning experiments between ringwoodite and ferropericlase, and that this results in different phase diagrams for FeSiO 3 and the post-spinel part of Mg 2 SiO 4 –Fe 2 SiO 4 . We show that the existence of a phase field coesite + ringwoodite in the phase diagram of FeSiO 3 is possible and that it might be used to fine-tune pressure scales. We demonstrate that the phase boundary between coesite and quartz is very sensitive to the low-temperature heat capacity of coesite and that heat capacity data of β-quartz are too large to be reconciled with the phase boundary between β-quartz and coesite. We compare our results with seismic data associated with the 410 km seismic discontinuity.

Published
2019

15. Thermodynamic properties of geikielite (MgTiO3) and ilmenite (FeTiO3) derived from vibrational methods combined with Raman and infrared spectroscopic data.

Author

Jacobs, Michael H. G., van den Berg, Arie P., Schmid-Fetzer, Rainer, de Vries, Jellie, van Westrenen, Wim, and Zhao, Yue

Subjects
*ILMENITE, *MODULUS of rigidity, *POLAR effects (Chemistry), *BULK modulus, *DENSITY of states, *HEAT capacity
Abstract

We present a model for the lattice vibrational density of states of MgTiO3 (geikielite) and FeTiO3 (ilmenite) that predicts thermodynamic properties, in agreement with observational data. The model is based on Kieffer's method combined with spectroscopic data. For both substances experimental data sets are influenced by non-stoichiometry. For geikielite that affects the volume, whereas for ilmenite volume and bulk modulus are affected. We show that Kieffer's method enables predicting bulk moduli in pressure–temperature space. We demonstrate that intrinsic anharmonicity or electronic effects significantly affect the heat capacity of ilmenite, whereas that is not the case for geikielite. We use Kieffer's method to derive multiple-Einstein models, from which we demonstrate that thermodynamic properties are insignificantly influenced by dispersion in Grüneisen, mode-q and anharmonicity parameters for both substances. We show that our results enable predicting thermodynamic properties and shear modulus of the solid solution formed from geikielite and ilmenite. Geikielite and ilmenite are added to our thermodynamic database for the system MgO–SiO2–FeO, to enable modeling phase stability and physical properties of titanium-rich reservoirs in the Earth's Moon. [ABSTRACT FROM AUTHOR]

Published
2022
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34. Rheological transition in mantle convection with a composite temperature-dependent, non-Newtonian and Newtonian rheology

Author

Van Den Berg, Arie P, Yuen, David A, and Van Keken, Peter E

Subjects
Geophysics
Abstract

Numerical simulations of mantle convection with a composite temperature-dependent, Newtonian and non-Newtonian creep law have revealed a transition in the dominant creep mechanism with the increasing vigour of convection. Newtonian creep is found to dominate in the low Rayleigh number regime. With sufficiently high effective Rayleigh number, the overall creep mechanism in the convective flow becomes non-Newtonian. The transitional Rayleigh number increases strongly with the activation energy. These results would suggest a scenario that in the early epochs of Earth the flow in the mantle would have been governed by non-Newtonian rheology and would have exhibited both strong spatial and temporal fluctuations. With time the flow mechanism would behave like a Newtonian fluid and would have a different time-dependent character. In time-dependent Newtonian-dominated flows there are still localized features with distinctly non-Newtonian character. Our analysis of the relative contributions to the lateral viscosity field supports the idea that the inference of the nature of lateral viscosity heterogeneities by seismic tomography may be strongly contaminated by the dominant non-Newtonian contributions to the total lateral viscosity field.

Published
1995
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36. Effects of depth-variations in creep laws on the formation of plates in mantle dynamics

Author

Van Den Berg, Arie P, Van Keken, Peter E, and Yuen, David A

Subjects
Geophysics
Abstract

The influences of depth-varying rheologies on the structure of mantle convection and the near surface flow fields are studied. Upwelling flows crossing the upper-lower mantle boundary become considerably thinner and faster. Streamlines are concentrated near the surface and other platelike characteristics are enhanced by this type of rheological stratification in which the averaged effective viscosity of the upper mantle is about two orders of magnitude lower than that of the lower mantle. The presence of a lithosphere with a higher nonlinear dependence in the flow law further promotes platelike behavior. Platelike character of the top boundary-layer is encouraged by a decreasing depth-dependent viscosity in the non-Newtonian upper-mantle and by greater convective vigor.

Published
1991

39. Thermophysical properties and phase diagrams in the system MgO–SiO2–FeO at upper mantle and transition zone conditions derived from a multiple-Einstein method.

Author

Jacobs, Michael H. G., Schmid-Fetzer, Rainer, and van den Berg, Arie P.

Subjects
THERMOPHYSICAL properties, PHASE diagrams, INNER cities, HEAT capacity, DENSITY of states, EARTH'S mantle
Abstract

We applied a lattice vibrational technique, based on representing the vibrational density of states with multiple-Einstein frequencies, to determine consistency of data on thermophysical properties and phase diagrams in the system MgO–FeO–SiO2. We present analyses of these data in the temperature range between 0 and 2000 K and pressure range between 0 and 20 GPa. The result is a database containing phases relevant to the Earth upper mantle and transition zone. We show that consistency of different datasets associated with the dissociation of the ringwoodite form of Fe2SiO4 depends on the crucible material that has been used to perform partitioning experiments between ringwoodite and ferropericlase, and that this results in different phase diagrams for FeSiO3 and the post-spinel part of Mg2SiO4–Fe2SiO4. We show that the existence of a phase field coesite + ringwoodite in the phase diagram of FeSiO3 is possible and that it might be used to fine-tune pressure scales. We demonstrate that the phase boundary between coesite and quartz is very sensitive to the low-temperature heat capacity of coesite and that heat capacity data of β-quartz are too large to be reconciled with the phase boundary between β-quartz and coesite. We compare our results with seismic data associated with the 410 km seismic discontinuity. [ABSTRACT FROM AUTHOR]

Published
2019
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46. Recipient’s Genetic R702W NOD2 Variant Is Associated with an Increased Risk of Bacterial Infections after Orthotopic Liver Transplantation

Author

Janse, Marcel, primary, de Rooij, Bert-Jan F., additional, van Hoek, Bart, additional, van den Berg, Arie P., additional, Porte, Robert J., additional, Blokzijl, Hans, additional, Coenraad, Minneke J., additional, Hepkema, Bouke G., additional, Schaapherder, Alexander F., additional, Ringers, Jan, additional, Weersma, Rinse K., additional, and Verspaget, Hein W., additional

Published
2013
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