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Abstract
The melting curve of NiSi has been determined to 70 GPa on the basis of
laser-heated diamond anvil cell (LH-DAC) experiments in which changes in
the gradient of temperature vs. laser power functions were used as the
melting criterion. The melting curve was corroborated with in situ
X-ray diffraction experiments in both the LH-DAC and multi-anvil press
in which the appearance of liquid diffuse scattering in the diffraction
patterns was used as the melting criterion. At all pressures, the NiSi
melting curve is lower than that of FeSi, with the difference in melting
temperature reaching a maximum of 900 K at 14 GPa. The location of the
B31 + B20 + L triple point has been constrained to 12 ± 2 GPa and
1550 ± 100 K and the B20 + B2 + L triple point to 28.5 ± 1.5 GPa and
2165 ± 60 K. On the basis of the in situ LH-DAC experiments the Clapeyron slope of the B20 → B2 transition is estimated at −67 MPa K−1.
Extrapolation of the B2-NiSi liquidus to core-mantle boundary (CMB)
conditions (135 GPa) suggests the melting point of NiSi (3700 ± 400 K)
will be only marginally lower than that of isostructural FeSi
(4000 ± 200 K). Thus any (Fe,Ni)Si solid solution present within the D″
layer is expected to remain solid, with the possible exception of the
very hottest region adjacent to the CMB.
Original language | English |
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Pages (from-to) | 13-23 |
Number of pages | 11 |
Journal | Physics of the Earth and Planetary Interiors |
Volume | 233 |
DOIs | |
Publication status | Published - Aug 2014 |
Bibliographical note
Date of Acceptance: 09/05/2014Research Groups and Themes
- PetrologyGroup
- PetrologyLabs
Keywords
- NiSi
- Melting
- High-pressure
- In situ
- LH-DAC
- High-pressure phase
- Earth's inner-core
- X-ray-diffraction
- Diamond-anvil cell
- Equation-of-state
- Extreme conditions
- Si alloys
- FeSi
- Iron
- Transitions
Fingerprint
Dive into the research topics of 'The NiSi melting curve to 70 GPa'. Together they form a unique fingerprint.Projects
- 2 Finished
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Diffusion in the DAC: Probing the physical state of the Earth's inner core
Lord, O. T. (Principal Investigator)
30/09/13 → 30/09/16
Project: Research
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METALLURGY AT EXTREME CONDITIONS: MOLTEN IRON-ALLOY CONSTRAINTS ON THE LIGHT ELEMENTS IN EARTH'S CORE
Walter, M. J. (Principal Investigator)
1/03/09 → 1/03/11
Project: Research
Profiles
-
Dr Oliver T Lord
- School of Earth Sciences - Senior Lecturer
- Geophysics
- Petrology (formerly BEEST)
Person: Academic , Member