skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Temperature of Earth's core constrained from melting of Fe and Fe 0.9 Ni 0.1 at high pressures

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1347240
Grant/Contract Number:
FG02-94ER14466; AC02-06CH11357
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Earth and Planetary Science Letters
Additional Journal Information:
Journal Volume: 447; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-06 09:35:07; Journal ID: ISSN 0012-821X
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Zhang, Dongzhou, Jackson, Jennifer M., Zhao, Jiyong, Sturhahn, Wolfgang, Alp, E. Ercan, Hu, Michael Y., Toellner, Thomas S., Murphy, Caitlin A., and Prakapenka, Vitali B.. Temperature of Earth's core constrained from melting of Fe and Fe 0.9 Ni 0.1 at high pressures. Netherlands: N. p., 2016. Web. doi:10.1016/j.epsl.2016.04.026.
Zhang, Dongzhou, Jackson, Jennifer M., Zhao, Jiyong, Sturhahn, Wolfgang, Alp, E. Ercan, Hu, Michael Y., Toellner, Thomas S., Murphy, Caitlin A., & Prakapenka, Vitali B.. Temperature of Earth's core constrained from melting of Fe and Fe 0.9 Ni 0.1 at high pressures. Netherlands. doi:10.1016/j.epsl.2016.04.026.
Zhang, Dongzhou, Jackson, Jennifer M., Zhao, Jiyong, Sturhahn, Wolfgang, Alp, E. Ercan, Hu, Michael Y., Toellner, Thomas S., Murphy, Caitlin A., and Prakapenka, Vitali B.. 2016. "Temperature of Earth's core constrained from melting of Fe and Fe 0.9 Ni 0.1 at high pressures". Netherlands. doi:10.1016/j.epsl.2016.04.026.
@article{osti_1347240,
title = {Temperature of Earth's core constrained from melting of Fe and Fe 0.9 Ni 0.1 at high pressures},
author = {Zhang, Dongzhou and Jackson, Jennifer M. and Zhao, Jiyong and Sturhahn, Wolfgang and Alp, E. Ercan and Hu, Michael Y. and Toellner, Thomas S. and Murphy, Caitlin A. and Prakapenka, Vitali B.},
abstractNote = {},
doi = {10.1016/j.epsl.2016.04.026},
journal = {Earth and Planetary Science Letters},
number = C,
volume = 447,
place = {Netherlands},
year = 2016,
month = 8
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.epsl.2016.04.026

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • The melting points of fcc- and hcp-structured Fe 0.9Ni 0.1 and Fe are measured up to 125 GPa using laser heated diamond anvil cells, synchrotron Mossbauer spectroscopy, and a recently developed fast temperature readout spectrometer. The onset of melting is detected by a characteristic drop in the time integrated synchrotron Mfissbauer signal which is sensitive to atomic motion. The thermal pressure experienced by the samples is constrained by X-ray diffraction measurements under high pressures and temperatures. The obtained best-fit melting curves of fcc-structured Fe and Fe 0.9Ni 0.1 fall within the wide region bounded by previous studies. We are ablemore » to derive the gamma-is an element of-1 triple point of Fe and the quasi triple point of Fe0.9Ni0.1 to be 110 ± 5 GPa, 3345 ± 120 K and 116 ± 5 GPa, 3260 ± 120 K, respectively. The measured melting temperatures of Fe at similar pressure are slightly higher than those of Fe 0.9Ni 0.1 while their one sigma uncertainties overlap. Using previously measured phonon density of states of hcp-Fe, we calculate melting curves of hcp-structured Fe and Fe 0.9Ni 0.1 using our (quasi) triple points as anchors. The extrapolated Fe 0.9Ni 0.1 melting curve provides an estimate for the upper bound of Earth's inner core-outer core boundary temperature of 5500 ± 200 K. The temperature within the liquid outer core is then approximated with an adiabatic model, which constrains the upper bound of the temperature at the core side of the core -mantle boundary to be 4000 ± 200 K. We discuss a potential melting point depression caused by light elements and the implications of the presented core -mantle boundary temperature bounds on phase relations in the lowermost part of the mantle.« less
  • The melting temperature of lead and sodium was redetermined as a function of pressure in a new pressure cell made up of low strength materials. Many of the anomalies reported in a prior determination of the melting curve of lead have largely disappeared. The slope of our new melting curve for lead is in close agreement with the slope computed from thermochemical data. One new curve for sodium differs only slightly from the prior published curves.
  • Two experimental approaches dealing with the determination of melting at high static pressures are described and analyzed. With the sample squeezed inside a diamond anvil cell, high temperatures up to the solid-liquid transition are obtained using Nd:YAG laser heating. Two methods have been investigated. In the first technique, the heating is accomplished with a pulsed laser and the brief radiation variations (t {lt} 10 ms) emitted from the sample are recorded with two high-speed infrared detectors. The melting location is defined by a plateau or changes of slope of the signals, and the temperatures are calculated by assuming a constantmore » value of emissivity factor at the end of the transition over the studied pressure range. The second system employs a continuous laser and a two-dimensional CCD detector to measure temperatures using multispectral pyrometry. Melting is detected from criteria related either to textural change in the sample involving interference contrast under a laser illumination or to the specific variations of temperatures and emissivity as a function of laser power. Thermal radiation is fitted to Planck's law with temperature and emissivity as the free parameters. Advantages and drawbacks are presented from results obtained on pure uranium.« less
  • No abstract prepared.