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Two-step nucleation of the Earth’s inner core

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America
 [1];  [2];  [2];  [3];  [4]
  1. Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027,
  2. Ames Laboratory, US Department of Energy, Ames, IA 50011,
  3. Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027,, Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027,, Lamont–Doherty Earth Observatory, Columbia University, Palisades, NY 10964,
  4. Department of Physics, Iowa State University, Ames, IA 50011
+ Show Author Affiliations
Significance

Understanding the formation of the Earth’s inner core is essential to understanding the geodynamo and Earth's history. However, recent attempts to explain the initial solidification of the inner core have been unsuccessful. The supercooling necessary to form hcp iron is unrealistically large and creates the “inner core nucleation paradox.” Our work demonstrates that molten iron can crystallize via a two-step nucleation process involving the intermediate bcc phase under core conditions. This mechanism significantly reduces the required undercooling necessary to nucleate solid iron. This work also suggests that bcc and hcp iron have similar free energies at pressures near the inner core center.

Research Organization:
Columbia Univ., New York, NY (United States); Iowa State Univ., Ames, IA (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
Grant/Contract Number:
AC02-07CH11358; SC0019759
OSTI ID:
1838410
Alternate ID(s):
OSTI ID: 1904317
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 2 Vol. 119; ISSN 0027-8424
Publisher:
Proceedings of the National Academy of SciencesCopyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Earth's inner core
atomic-scale simulation
solidification
supercooling
two-step nucleation