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Title: Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase

Abstract

We report the discovery of a new allotrope of iron by first principles calculations. This phase has Pmn2(1) symmetry, a six-atom unit cell (hence the name Fe-6), and the highest magnetization density (M-s) among all the known crystalline phases of iron. Obtained from the structural optimizations of the Fe3C-cementite crystal upon carbon removal, Pmn2(1) Fe-6 is shown to result from the stabilization of a ferromagnetic FCC phase, further strained along the Bain path. Although metastable from 0 to 50 GPa, the new phase is more stable at low pressures than the other well-known HCP and FCC allotropes and smoothly transforms into the FCC phase under compression. If stabilized to room temperature, for example, by interstitial impurities, Fe-6 could become the basis material for high M-s rare-earth-free permament magnets and high-impact applications such as light-weight electric engine rotors or high-density recording media. The new phase could also be key to explaining the enigmatic high M-s of Fe16N2, which is currently attracting intense research activity.

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1211372
DOE Contract Number:  
0472-1595
Resource Type:
Journal Article
Journal Name:
Journal of Physics. Condensed Matter
Additional Journal Information:
Journal Volume: 27; Journal Issue: 1; Journal ID: ISSN 0953-8984
Country of Publication:
United States
Language:
English

Citation Formats

Umemoto, K, Himmetoglu, B, Wang, JP, Wentzcovitch, RM, and Cococcioni, M. Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase. United States: N. p., 2014. Web. doi:10.1088/0953-8984/27/1/016001.
Umemoto, K, Himmetoglu, B, Wang, JP, Wentzcovitch, RM, & Cococcioni, M. Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase. United States. https://doi.org/10.1088/0953-8984/27/1/016001
Umemoto, K, Himmetoglu, B, Wang, JP, Wentzcovitch, RM, and Cococcioni, M. Wed . "Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase". United States. https://doi.org/10.1088/0953-8984/27/1/016001.
@article{osti_1211372,
title = {Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase},
author = {Umemoto, K and Himmetoglu, B and Wang, JP and Wentzcovitch, RM and Cococcioni, M},
abstractNote = {We report the discovery of a new allotrope of iron by first principles calculations. This phase has Pmn2(1) symmetry, a six-atom unit cell (hence the name Fe-6), and the highest magnetization density (M-s) among all the known crystalline phases of iron. Obtained from the structural optimizations of the Fe3C-cementite crystal upon carbon removal, Pmn2(1) Fe-6 is shown to result from the stabilization of a ferromagnetic FCC phase, further strained along the Bain path. Although metastable from 0 to 50 GPa, the new phase is more stable at low pressures than the other well-known HCP and FCC allotropes and smoothly transforms into the FCC phase under compression. If stabilized to room temperature, for example, by interstitial impurities, Fe-6 could become the basis material for high M-s rare-earth-free permament magnets and high-impact applications such as light-weight electric engine rotors or high-density recording media. The new phase could also be key to explaining the enigmatic high M-s of Fe16N2, which is currently attracting intense research activity.},
doi = {10.1088/0953-8984/27/1/016001},
url = {https://www.osti.gov/biblio/1211372}, journal = {Journal of Physics. Condensed Matter},
issn = {0953-8984},
number = 1,
volume = 27,
place = {United States},
year = {2014},
month = {11}
}