{{Short description|Native metal}} {{Infobox mineral |name=Tetrataenite|boxwidth=|boxbgcolor= |image=Tetrataenite-138026.jpg |imagesize=260px|alt= |caption=Silvery-bright tetrataenite crystals |category=Native element minerals |formula={{chem2|FeNi}} | IMAsymbol = Ttae<ref>{{cite journal |last1=Warr |first1=Laurence N. |title=IMA–CNMNC approved mineral symbols |journal=Mineralogical Magazine |date=June 2021 |volume=85 |issue=3 |pages=291–320 |doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |doi-access=free }}</ref> |molweight=57.27 gm |strunz=1.AE.10 |system=Tetragonal |class=Domatic (m) <br/><small>(same H-M symbol)</small> |symmetry=''P4/mmm''<ref>{{cite journal |last1=Montes-Arango |first1=A.M. |last2=Marshall |first2=L.G. |last3=Fortes |first3=A.D. |last4=Bordeaux |first4=N.C. |last5=Langridge |first5=S. |last6=Barmak |first6=K. |last7=Lewis |first7=L.H. |title=Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi |journal=Acta Materialia |date=September 2016 |volume=116 |pages=263–269 |doi=10.1016/j.actamat.2016.06.050 |bibcode=2016AcMat.116..263M |doi-access=free }}</ref> |unit cell=22.92 ų |color=gray white, silver white |colour= |habit=Granular – Common texture observed in granite and other igneous rock |twinning= |cleavage=none |fracture=malleable |tenacity=|mohs=3.5|luster=metallic|streak=gray |diaphaneity=opaque|gravity=|density=8.275|polish=|opticalprop= |refractive=|birefringence=|pleochroism=|2V= |dispersion=|extinction=|length fast/slow=|fluorescence=|absorption=|melt=|fusibility= |diagnostic= |solubility= |impurities=Co, Cu, P |alteration=|other=|prop1=|prop1text= |references=<ref name=atlas>{{Cite web|url=https://www.mineralienatlas.de/lexikon/index.php/MineralData?lang=de&mineral=Tetrataenite|title=Mineralienatlas – Fossilienatlas|website=www.mineralienatlas.de|access-date=1 April 2023}}</ref><ref name="Mindat2" /><ref name=Webmin>{{cite web |title=Tetrataenite |url=http://www.webmineral.com/data/Tetrataenite.shtml |publisher=webmineral.com}}</ref> [http://webmineral.com/data/Tetrataenite.shtml#.Ws0EzNPwau7] [https://www.mindat.org/min-3927.html]
}} '''Tetrataenite''' is a native metal alloy composed of chemically-ordered L1<sub>0</sub>-type {{chem2|FeNi}}, recognized as a mineral in 1980.<ref name=":12" /> The mineral is named after its tetragonal crystal structure and its relation to the iron-nickel alloy, taenite, which is chemically disordered (A1) phase with an underlying fcc lattice.<ref>{{Cite web|url=https://www.mindat.org/min-3927.html|title=Tetrataenite: Tetrataenite mineral information and data.|website=www.mindat.org|access-date=2018-03-30}}</ref> Tetrataenite is one of the mineral phases found in meteoric iron.<ref name="Webmin2">{{cite web|url=http://www.webmineral.com/data/Tetrataenite.shtml|title=Tetrataenite|publisher=webmineral.com}}</ref><ref name="Mindat2">{{Cite web|url=http://www.mindat.org/min-3927.html|title=Tetrataenite: Mineral information, data and localities.|access-date=1 April 2023}}</ref><ref name="handbook2">{{Cite web|url=http://www.handbookofmineralogy.com/pdfs/tetrataenite.pdf|title=''Handbook of Mineralogy'' – Tetrataenite|access-date=1 April 2023|archive-date=5 October 2012|archive-url=https://web.archive.org/web/20121005231630/http://www.handbookofmineralogy.com/pdfs/tetrataenite.pdf}}</ref> Before its discovery in meteoritic samples, experimental synthesis of the L1<sub>0</sub> phase was first reported in 1962 by Louis Néel and co-workers, following neutron irradiation of a chemically disordered FeNi sample under an applied magnetic field.<ref name=":4">{{cite journal |last1=Paulevé |first1=J. |last2=Dautreppe |first2=D. |last3=Laugier |first3=J. |last4=Néel |first4=L. |title=Une nouvelle transition ordre-désordre dans Fe-Ni (50-50) |trans-title=A new order-disorder transition in Fe-Ni (50-50) |language=fr |journal=Journal de Physique et le Radium |date=1962 |volume=23 |issue=10 |pages=841–843 |id={{HAL|jpa-00236692}} |doi=10.1051/jphysrad:019620023010084100 |url=https://hal.science/jpa-00236692 }}</ref><ref name=":5">{{cite journal |last1=Néel |first1=L. |last2=Pauleve |first2=J. |last3=Pauthenet |first3=R. |last4=Laugier |first4=J. |last5=Dautreppe |first5=D. |title=Magnetic Properties of an Iron—Nickel Single Crystal Ordered by Neutron Bombardment |journal=Journal of Applied Physics |date=March 1964 |volume=35 |issue=3 |pages=873–876 |doi=10.1063/1.1713516 |bibcode=1964JAP....35..873N |url=https://hal.science/hal-02887454 }}</ref><ref name=":6">{{cite journal |last1=Paulevé |first1=J. |last2=Chamberod |first2=A. |last3=Krebs |first3=K. |last4=Bourret |first4=A. |title=Magnetization Curves of Fe–Ni (50–50) Single Crystals Ordered by Neutron Irradiation with an Applied Magnetic Field |journal=Journal of Applied Physics |date=February 1968 |volume=39 |issue=2 |pages=989–990 |doi=10.1063/1.1656361 |bibcode=1968JAP....39..989P }}</ref> Compared to the magnetically soft, chemically disordered A1 phase (taenite), the tetragonal L1<sub>0</sub> structure of tetrataenite leads to good hard magnetic properties, including a large uniaxial magnetocrystalline anisotropy energy.<ref name=":5" /><ref name=":7" /> Consequently, it is under consideration for applications as a rare-earth-free permanent magnet.<ref name=":0">{{cite journal |last1=Lewis |first1=L H |last2=Mubarok |first2=A |last3=Poirier |first3=E |last4=Bordeaux |first4=N |last5=Manchanda |first5=P |last6=Kashyap |first6=A |last7=Skomski |first7=R |last8=Goldstein |first8=J |last9=Pinkerton |first9=F E |last10=Mishra |first10=R K |last11=Kubic Jr |first11=R C |last12=Barmak |first12=K |title=Inspired by nature: investigating tetrataenite for permanent magnet applications |journal=Journal of Physics: Condensed Matter |date=12 February 2014 |volume=26 |issue=6 |article-number=064213 |doi=10.1088/0953-8984/26/6/064213 |pmid=24469336 }}</ref>
== Formation == Tetrataenite forms naturally in 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.<ref name=":12">{{cite journal |last1=Clarke |first1=Roy S. |last2=Scott |first2=Edward R. D. |title=Tetrataenite—ordered FeNi, a new mineral in meteorites |journal=American Mineralogist |date=August 1980 |volume=65 |issue=7–8 |pages=624–630 |url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/65/7-8/624/41156/Tetrataenite-ordered-FeNi-a-new-mineral-in }}</ref> It is found most abundantly in slow-cooled chondrite meteorites,<ref>{{Cite web|url=http://webmineral.com/data/Tetrataenite.shtml#.Wr6H69Pwau4|title=Tetrataenite Mineral Data|last=Barthelmy|first=Dave|website=webmineral.com|access-date=2018-04-10}}</ref> as well as in mesosiderites.<ref name=":12" /> At high (as much as 52%) Ni content and temperatures below 320 °C (the chemical order-disorder transition temperature<ref name=":4" />), tetrataenite is broken down from taenite and distorts its face centered cubic crystal structure to form the chemically ordered, tetragonal L1<sub>0</sub> structure.<ref name=":2">{{cite web | url=https://www.britannica.com/science/taenite | title=Taenite | Metallic, Nickel-Iron Alloy | Britannica }}</ref> Computational investigations into the phase stability of Fe-Ni alloys have suggested that ferromagnetic ordering plays a key role in making the chemically ordered L1<sub>0</sub> structure thermodynamically stable.<ref>{{cite journal |last1=Woodgate |first1=Christopher D. |last2=Lewis |first2=Laura H. |last3=Staunton |first3=Julie B. |title=Integrated ab initio modelling of atomic ordering and magnetic anisotropy for design of FeNi-based magnets |journal=npj Computational Materials |date=29 November 2024 |volume=10 |issue=1 |page=272 |doi=10.1038/s41524-024-01435-y |arxiv=2401.02809 |bibcode=2024npjCM..10..272W }}</ref>
In 2015, it was reported that tetrataenite was found in a terrestrial rock – a magnetite body from the Indo-Myanmar ranges of northeast India.<ref name=":1">{{cite journal |last1=Nayak |first1=B. |last2=Meyer |first2=F. M. |title=Tetrataenite in terrestrial rock |journal=American Mineralogist |date=2015 |volume=100 |issue=1 |pages=209–214 |doi=10.2138/am-2015-5061 |bibcode=2015AmMin.100..209N }}</ref>
It is reported that the L1<sub>0</sub> phase can be synthetically produced by neutron- or electron-irradiation of chemically disordered (A1) {{chem2|FeNi}} below 593 K,<ref name=":4" /><ref name=":5" /><ref name=":6" /> by hydrogen-reduction of nanometric {{chem2|NiFe2O4}},<ref name=":1" /> or by combined application of mechanical stress and magnetic field during annealing of the chemically disordered A1 phase.<ref name="lhn">{{cite journal |last1=Lewis |first1=Laura H. |last2=Stamenov |first2=Plamen S. |title=Accelerating Nature: Induced Atomic Order in Equiatomic FeNi |journal=Advanced Science |date=February 2024 |volume=11 |issue=7 |article-number=e2302696 |doi=10.1002/advs.202302696 |pmc=10870030 |pmid=38072671 }}</ref>
===Potential laboratory protocols for bulk synthesis===
==== Applied Stress and Magnetic Field ==== It has been reported that the combined application of mechanical stress and a modest magnetic field during the annealing process can accelerate the formation of the atomically ordered L1<sub>0</sub> phase in bulk samples.<ref name=lhn/>
==== Addition of Phosphorus (Article Retracted) ==== In 2022, it was reported that mixing iron and nickel together in specific quantities, with a phosphorus catalyst, and smelting the mixture, formed tetrataenite in bulk quantities, in seconds.<ref>{{Cite journal |last1=Ivanov |first1=Yurii P. |last2=Sarac |first2=Baran |last3=Ketov |first3=Sergey V. |last4=Eckert |first4=Jürgen |last5=Greer |first5=A. Lindsay |date=2022-10-25 |title=Direct Formation of Hard-Magnetic Tetrataenite in Bulk Alloy Castings |journal=Advanced Science |volume=10 |issue=1 |language=en |article-number=2204315 |doi=10.1002/advs.202204315 |pmid=36281692 |pmc=9811435 }}{{Retracted|doi=10.1002/advs.202416229|pmid=39691068|https://retractionwatch.com/2025/10/08/cosmic-magnet-study-retracted-after-cleaning-agent-wipes-away-results/ ''Retraction Watch''|intentional=yes}}</ref><ref>{{cite web | url=https://patents.google.com/patent/US11462358B2/en | title=Method of tetratenite production and system therefor }}</ref> However, in late 2024, the article originally reporting this result was retracted by the journal<ref>{{Cite journal |title=RETRACTION: Direct Formation of Hard-Magnetic Tetrataenite in Bulk Alloy Castings |journal=Advanced Science |date=2025 |volume=12 |issue=4 |article-number=2416229 |doi=10.1002/advs.202416229 |doi-access=free |pmid=39691068 |pmc=11775545 }}</ref> due to 'misinterpretation of the experimental data'. A subsequent Comment, published by a group containing many of the original article's authors, provided both reinterpretation of the original data as well as new measurements, and showed that the Bragg peaks originally attributed to presence of tetrataenite in the samples were, in fact, caused by the presence of phosphides.<ref>{{Cite journal |last1=Houghton |first1=Owain S. |last2=Loudon |first2=James C. |last3=Twitchett-Harrison |first3=Alison C. |last4=Panagiotopoulos |first4=Nikolaos T. |last5=Lampronti |first5=Giulio I. |last6=Costa |first6=Miguel B. |last7=Harrison |first7=Richard J. |last8=Greer |first8=A. Lindsay |title=Reinterpretation of Report of Tetrataenite in Bulk Alloy Castings |journal=Advanced Science |date=2025 |volume=12 |issue=4 |article-number=2408796 |doi=10.1002/advs.202408796 |doi-access=free |pmid=39680740 |pmc=11775553 }}</ref>
== Crystal structure == Tetrataenite has a highly ordered crystal structure,<ref name=":2"/> appearing creamy in color and displaying optical anisotropy.<ref name=":12"/> Its appearance is distinguishable from taenite, which is dark gray with low reflectivity.<ref name=":1" /> {{chem2|FeNi}} easily forms into a cubic crystal structure, but does not have magnetic anisotropy in this form. Three variants of the L1<sub>0</sub> tetragonal crystal structure have been found, as chemical ordering can occur along any of the three axes.<ref name=":0" />
== Magnetic properties == Tetrataenite displays permanent magnetization, in particular, high coercivity.<ref name=":3">{{Cite journal |last=Dos Santos |first=E. |date=6 September 2014 |title=Kinetics of tetrataenite disordering |journal=Journal of Magnetism and Magnetic Materials |volume=375 |pages=234–241 |doi=10.1016/j.jmmm.2014.09.051}}</ref> It has a large uniaxial magnetocrystalline anisotropy<ref name=":7">{{Cite journal |last1=Woodgate |first1=Christopher D. |last2=Patrick |first2=Christopher E. |last3=Lewis |first3=Laura H. |last4=Staunton |first4=Julie B. |date=2023-10-28 |title=Revisiting Néel 60 years on: The magnetic anisotropy of L10 FeNi (tetrataenite) |journal=Journal of Applied Physics |volume=134 |issue=16 |doi=10.1063/5.0169752 |doi-access=free |arxiv=2307.15470 }}</ref> and theoretical magnetic energy product, the maximum amount of magnetic energy stored, over 335 kJ m<sup>−3</sup>.<ref name=":3" /> The L1<sub>0</sub> phase has a theoretical Curie temperature of over 1000 K,<ref name=":7" /> resulting in a magnetic anisotropy which is predicted to remain large up to and beyond room temperature.
== 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.<ref>{{cite journal |last1=Einsle |first1=Joshua F. |last2=Eggeman |first2=Alexander S. |last3=Martineau |first3=Ben H. |last4=Saghi |first4=Zineb |last5=Collins |first5=Sean M. |last6=Blukis |first6=Roberts |last7=Bagot |first7=Paul A. J. |last8=Midgley |first8=Paul A. |last9=Harrison |first9=Richard J. |title=Nanomagnetic properties of the meteorite cloudy zone |journal=Proceedings of the National Academy of Sciences |date=4 December 2018 |volume=115 |issue=49 |pages=E11436–E11445 |doi=10.1073/pnas.1809378115 |pmc=6298078 |pmid=30446616 |bibcode=2018PNAS..11511436E |doi-access=free }}</ref>
==See also== * Glossary of meteoritics * Superlattice ==References== {{Reflist}}
Category:Meteorite minerals Category:Monoclinic minerals Category:Minerals in space group 6 Category:Native element minerals