Tetrataenite

Tetrataenite
Silvery-bright tetrataenite crystals
General
Category Native element minerals
Formula
(repeating unit)		 FeNi
Strunz classification 1.AE.10
Crystal system Tetragonal
Crystal class Domatic (m)
(same H-M symbol)
Space group Pm
Unit cell 22.92 ų
Identification
Formula mass 57.27 gm
Color gray white, silver white
Crystal habit Granular - Common texture observed in granite and other igneous rock
Cleavage none
Fracture malleable
Mohs scale hardness 3.5
Luster metallic
Streak gray
Diaphaneity opaque
Density 8.275
Common impurities Co,Cu,P
References

[1][2][3]

Tetrataenite is a native metal composed of chemically-ordered L10-type FeNi, recognized as a mineral in 1980.[4][5] The mineral is named after its tetragonal crystal structure and its relation to the iron-nickel alloy, taenite.[6] It is one of the mineral phases found in meteoric iron.[7][2][8]

Formation

Tetrataenite forms naturally iron meteorites that contain taenite that are slow-cooled at a rate of a few degrees per million years, which allows for ordering of the Fe and Ni atoms.[9][10] It is found most abundantly in slow-cooled chondrite meteorites,[11] as well as in mesosiderites.[9] At high (as much as 52%) Ni content and temperatures below 320 °C (the order-disorder transition temperature), tetrataenite is broken down from taenite and distorts its face centered cubic crystal structure to form the tetragonal L10 structure.[12][10]

The L10 phase can be synthetically produced by neutron- or electron-irradiation of FeNi below 593 K or by hydrogen-reduction of nanometric NiFe2O4, but only on a small scale.[10]

In 2015, it was reported that tetrataenite was found in a terrestrial rock - a magnetite body from the Indo-Myanmar ranges of northeast India.[10]

Crystal Structure

Tetrataenite has a highly ordered crystal structure,[12] appearing creamy in color and displaying optical anisotropy.[13] Its appearance is distinguishable from taenite, which is dark gray with low reflectivity.[10] FeNi easily forms into a cubic crystal structure, but does not have magnetic anisotropy in this form. Three variants of the L10 tetragonal crystal structure have been found, as chemical ordering can occur along any of the three axes.[4]

Magnetic Properties

Tetrataenite displays permanent magnetization, in particular, high coercivity.[5] It has a theoretical magnetic energy product, the maximum amount of magnetic energy stored, over 335 kJ m−3.[5]

Applications

Tetrataenite is a candidate for replacing rare-earth permanent magnets such as samarium and neodymium since both iron and nickel are earth-abundant and inexpensive.

See also

References

  1. ↑ Mineralienatlas
  2. 1 2 Mindat.org – Tetrataenite
  3. ↑ "Tetrataenite". webmineral.com.
  4. 1 2 Lewis, L. H. (January 27, 2014). "Inspired by nature: investigating tetrataenite for permanent magnet applications". Journal of Physics: Condensed Matter. IOP Publishing. 26 – via IOPscience.
  5. 1 2 3 Dos Santos, E. (6 September 2014). "Kinetics of tetrataenite disordering" (PDF). Journal of Magnetism and Magnetic Materials. 375: 234–241 – via ScienceDirect.
  6. ↑ "Tetrataenite: Tetrataenite mineral information and data". www.mindat.org. Retrieved 2018-03-30.
  7. ↑ "Tetrataenite". webmineral.com.
  8. ↑ Handbook of Mineralogy – Tetrataenite
  9. 1 2 Clarke, Roy S.; Scott, Edward R. D. (March 6, 1980). "Tetrataenite - ordered FeNi, a new mineral in meteorites" (PDF). American Mineralogist. 65: 624–630.
  10. 1 2 3 4 5 Nayak, Bibhuranjan (January 1, 2015). "Tetrataenite in terrestrial rock". American Mineralogist. 100: 209–214.
  11. ↑ Barthelmy, Dave. "Tetrataenite Mineral Data". webmineral.com. Retrieved 2018-04-10.
  12. 1 2 "Taenite." Britannica Academic, Encyclopædia Britannica, 6 Nov. 2009. academic-eb-com.ezproxy.neu.edu/levels/collegiate/article/taenite/342903. Accessed 30 Mar. 2018.
  13. ↑ Clarke, Roy S.; Scott, Edward R. D. (March 6, 1980). "Tetrataenite - ordered FeNi, a new mineral in meteorites" (PDF). American Mineralogist. 65: 624–630.


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