# Raymond Jeanloz
Raymond Jeanloz is an American geophysicist and high-pressure mineral physicist, professor of Earth and Planetary Science and of [Astronomy](https://www.edgepedia.org/astronomy) at the [University of California](https://www.edgepedia.org/university-of-california), Berkeley, whose laboratory experiments on minerals at the pressures of planetary interiors provided the first experimental constraints on the temperature at Earth's center.[1](https://astro.berkeley.edu/people/raymond-jeanloz) His research combines static compression in diamond-anvil cells with dynamic shock-wave methods to document the crystal structures and the elastic, thermal, and electronic properties of phases at high pressure.[2](https://www.nasonline.org/directory-entry/raymond-jeanloz-dtwvhf/) He was elected to the National Academy of Sciences in 2004 and has received a MacArthur Fellowship.[2](https://www.nasonline.org/directory-entry/raymond-jeanloz-dtwvhf/) • [3](https://www.hoover.org/profiles/raymond-jeanloz)
| Fact | Detail |
|---|---|
| Position | Professor of Earth and Planetary Science and Astronomy, UC Berkeley[1](https://astro.berkeley.edu/people/raymond-jeanloz) |
| Training | B.A. Amherst College (1975); Ph.D. Caltech (1979), advisor Thomas J. Ahrens[4](https://www.macfound.org/fellows/class-of-1988/raymond-jeanloz) • [5](https://thesis.caltech.edu/16138/) |
| Signature work | Iron melting curve to 250 GPa (Science, 1987), giving the first experimental upper bound on Earth's central temperature, about 6900 K; ["Static strength and equation of state of rhenium at ultra-high pressures" *Nature*, 1991 |[6](https://www.science.org/doi/10.1126/science.236.4798.181)
| Key result | Perovskite-structured magnesium silicate, stable only above 20 GPa, makes up the bulk of Earth's rocky interior[1](https://astro.berkeley.edu/people/raymond-jeanloz) |
| Pressure reach | Diamond anvils plus laser-driven compression, from the megabar to the gigabar range (0.3 Gbar)[1](https://astro.berkeley.edu/people/raymond-jeanloz) |
| Honors | NAS member (2004); MacArthur Fellowship; Macelwane, MSA, and Cozzarelli prizes; Szilard and Bethe awards[2](https://www.nasonline.org/directory-entry/raymond-jeanloz-dtwvhf/) • [3](https://www.hoover.org/profiles/raymond-jeanloz) |
## Education and career
Jeanloz received a B.A. from [Amherst College](https://www.edgepedia.org/amherst-college) in 1975 and a Ph.D. from the [California Institute of Technology](https://www.edgepedia.org/california-institute-of-technology) in 1979.[4](https://www.macfound.org/fellows/class-of-1988/raymond-jeanloz) His dissertation, *Physics of Mantle and Core Minerals*, was supervised by [Thomas J. Ahrens](https://www.edgepedia.org/thomas-j-ahrens); NASA's Technical Reports Server dates the thesis August 10, 1979, while the Caltech thesis repository catalogs it under 1980.[5](https://thesis.caltech.edu/16138/) • [7](https://ntrs.nasa.gov/citations/19800007272) The thesis itself reported a minimum estimated temperature of about 2800 K at the top of the outer core and a temperature near 2000 K in the mantle transition zone from olivine phase equilibria, an early sign of the questions he would pursue throughout his career.[5](https://thesis.caltech.edu/16138/)
After a faculty appointment at Harvard University, he joined the University of California at Berkeley, where he is professor of Earth and Planetary Science and of Astronomy and a senior fellow at the Miller Institute for Basic Research in Science.[1](https://astro.berkeley.edu/people/raymond-jeanloz) • [3](https://www.hoover.org/profiles/raymond-jeanloz)
## Research: the deep Earth
**The core's temperature.** In 1987, work published in *Science* measured the melting curve of iron to 250 gigapascals, finding 4800 ± 200 K at the core-mantle boundary pressure of 136 GPa; extrapolating the curve beyond the measured range gave 7600 ± 500 K at the inner core boundary pressure of 330 GPa.[6](https://www.science.org/doi/10.1126/science.236.4798.181) Corrected for impurity melting-point depression, these measurements implied 6600 K for an iron-rich alloy at the inner core boundary and a maximum of 6900 K at Earth's center, the first experimental upper bound on that temperature.[6](https://www.science.org/doi/10.1126/science.236.4798.181) The MacArthur Foundation summarizes the finding plainly: he and his students found that Earth's core is as hot as the surface of the Sun.[4](https://www.macfound.org/fellows/class-of-1988/raymond-jeanloz) He reviewed the state of the field in the 1990 Annual Review of Earth and Planetary Sciences article "The Nature of the Earth's Core".[8](https://www.annualreviews.org/content/journals/10.1146/annurev.ea.18.050190.002041)
**The mantle.** His group documented that a single perovskite-structured mineral, stable only at pressures above 20 GPa, makes up the bulk of Earth's rocky interior.[1](https://astro.berkeley.edu/people/raymond-jeanloz) [Experiments](https://www.edgepedia.org/experiments) published in *Science* in 1991 showed that liquid iron reacts chemically with silicate minerals at pressures of at least 2.4 × 1010 Pa: (Mg,Fe)SiO3 perovskite reacting with liquid iron at core-mantle-boundary pressures produces metallic Fe-Si alloys, plus FeO, SiO2 stishovite, and perovskite.[9](https://www.science.org/doi/10.1126/science.251.5000.1438) These reactions suggest that the lowermost 200 to 300 kilometers of the mantle, the [D″ layer](https://www.edgepedia.org/d-layer), is an extremely heterogeneous region, offering an explanation for the complex behavior of seismic waves near the core-mantle boundary and a possible influence on [Earth's magnetic field](https://www.edgepedia.org/earths-magnetic-field).[9](https://www.science.org/doi/10.1126/science.251.5000.1438)
## Research: planetary interiors
The same experimental program extends to other planets. DOE-supported experiments found that helium can separate from hydrogen at conditions inside Jupiter and Saturn, providing much of those planets' internal energy and observed luminosities; that water ice is likely superionic, with mobile protons, inside Uranus and Neptune; and that rock-forming oxides can become metallic inside super-Earths.[10](https://www.osti.gov/servlets/purl/1361129)
At the largest scales, his group pioneered combining diamond anvils with laser-driven compression, reaching atomic-scale pressures of 0.3 Gbar and states of chemical bonding he calls "kilovolt chemistry".[1](https://astro.berkeley.edu/people/raymond-jeanloz) Combining shock-wave and static techniques extends experiments from the million-atmosphere to the billion-atmosphere range, high enough to reproduce conditions inside super-giant planets and brown dwarfs.[2](https://www.nasonline.org/directory-entry/raymond-jeanloz-dtwvhf/)
## Static and dynamic compression compared
Diamond-anvil-cell experiments compress samples statically between gem-quality diamonds and are usually restricted to below 200 GPa; reaching terapascal pressures and temperatures of 10,000 K or more requires dynamic shock and ramp compression.[12](https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2019.00023/full) Laser-shock experiments on samples pre-compressed in diamond-anvil cells extend laboratory compression from the megabar to the gigabar range, beyond the atomic unit of pressure (294 Mbar).[1](https://astro.berkeley.edu/people/raymond-jeanloz)
The iron melting temperature at the inner core boundary remains contested. Jeanloz's 1987 melting curve gave 7600 ± 500 K at 330 GPa; shock-temperature measurements extrapolated 6830 ± 500 K in 1993, and later laser-shock x-ray diffraction work estimated about 6400 K at the same pressure.[6](https://www.science.org/doi/10.1126/science.236.4798.181) • [13](https://doi.org/10.1103/physrevlett.70.3931) • [14](https://www.osti.gov/servlets/purl/1728707) A 2020 gas-gun study reporting a consensus melting curve gave lower values, 4300 (250) K at the core-mantle boundary and 5950 (400) K at the inner core boundary.[15](https://doi.org/10.1029/2020gl087758) The spread, roughly 5950 K to 7600 K at inner-core pressure, is unresolved and directly affects inferred core temperature and heat flow.[6](https://www.science.org/doi/10.1126/science.236.4798.181) • [15](https://doi.org/10.1029/2020gl087758)
## Representative works
- "The Melting Curve of Iron to 250 Gigapascals: A Constraint on the Temperature at Earth's Center", *Science*, 1987, the experimental melting curve of iron to 250 GPa that gave the first experimental upper bound on the temperature at Earth's center. [DOI](https://www.science.org/doi/10.1126/science.236.4798.181)
- "Earth's Core-Mantle Boundary: Results of Experiments at High Pressures and Temperatures", *Science*, 1991, documenting chemical reactions between liquid iron and silicate minerals at core-mantle-boundary pressures. [DOI](https://www.science.org/doi/10.1126/science.251.5000.1438)
- "The Nature of the Earth's Core", *Annual Review of Earth and Planetary Sciences*, 1990, a review of the state of the field. [DOI](https://www.annualreviews.org/content/journals/10.1146/annurev.ea.18.050190.002041)
## Honors
Jeanloz's scientific research has been recognized by a MacArthur Fellowship, an American Geophysical Union Macelwane Award, a Mineralogical Society of America Award, and the National Academy of Sciences Cozzarelli Prize; his policy-related work, by the American Physical Society Leo Szilard Prize and the Federation of American Scientists' Hans Bethe Award.[3](https://www.hoover.org/profiles/raymond-jeanloz) He was an Annenberg Distinguished Visiting Fellow at the [Hoover Institution](https://www.edgepedia.org/hoover-institution) (2012–13).[3](https://www.hoover.org/profiles/raymond-jeanloz)
## References
1. Raymond Jeanloz | Astronomy, UC Berkeley. https://astro.berkeley.edu/people/raymond-jeanloz
2. Raymond Jeanloz, National Academy of Sciences member directory. https://www.nasonline.org/directory-entry/raymond-jeanloz-dtwvhf/
3. Raymond Jeanloz, Hoover Institution. https://www.hoover.org/profiles/raymond-jeanloz
4. Raymond Jeanloz, MacArthur Foundation. https://www.macfound.org/fellows/class-of-1988/raymond-jeanloz
5. *Physics of Mantle and Core Minerals*, CaltechTHESIS. https://thesis.caltech.edu/16138/
6. The Melting Curve of Iron to 250 Gigapascals: A Constraint on the Temperature at Earth's Center, Science, 1987. https://www.science.org/doi/10.1126/science.236.4798.181
7. Physics of mantle and core minerals, NASA NTRS. https://ntrs.nasa.gov/citations/19800007272
8. The Nature of the Earth's Core, Annual Review of Earth and Planetary Sciences, 1990. https://www.annualreviews.org/content/journals/10.1146/annurev.ea.18.050190.002041
9. Earth's Core-Mantle Boundary: Results of Experiments at High Pressures and Temperatures, Science, 1991. https://www.science.org/doi/10.1126/science.251.5000.1438
10. DOE grant final report, OSTI. https://www.osti.gov/servlets/purl/1361129
11. Measuring the melting curve of iron at super-Earth core conditions, NSF Public Access Repository. https://par.nsf.gov/biblio/10319932-measuring-melting-curve-iron-super-earth-core-conditions
12. Ultra-High Pressure Dynamic Compression of Geological Materials, Frontiers in Earth Science, 2019. https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2019.00023/full
13. Shock temperatures and melting of iron at Earth core conditions, Physical Review Letters, 1993. https://doi.org/10.1103/physrevlett.70.3931
14. Crystal Structure and Melting of Fe Shock X-ray Diffraction, OSTI. https://www.osti.gov/servlets/purl/1728707
15. Shock Melting Curve of Iron: A Consensus on the Temperature at the Earth's Inner Core Boundary, Geophysical Research Letters, 2020. https://doi.org/10.1029/2020gl087758
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Earth and climate scientists › Researchers in geology, geophysics, geochemistry, and hydrology › Mineralogy and mineral physics*
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