1995 ::: Low-spin γ-Fe-Ni(γLS) proposed as a new mineral in Fe-Ni-bearing meteorites: epitaxial intergrowth of γLS and tetrataenite as a possible equilibrium state at ∼20–40 at% Ni

D. G. Rancourt & R. B. Scorzelli

Journal of Magnetism and Magnetic Materials
Volume 150, Issue 1, 2 September 1995, Pages 30-36
https://doi.org/10.1016/0304-8853(95)00089-5

Abstract
We argue that the so-called paramagnetic phase seen by Mössbauer spectroscopy in taenite lamella from octahedrite meteorites, ataxite meteorites, the metal particles of Fe-Ni-bearing chondrite meteorites, and synthetic particle-irradiated Fe-Ni alloys is a low-spin γ-Fe-Ni phase (γLS), related to the close packed low-spin phases seen in the pressure-temperature phase diagrams of both metallic Fe and synthetic Fe-Ni alloys and many other Fe-alloy systems. At a given composition, this γLS phase is quite distinct from the ordinary (high-spin) γ-phase (γHS) in that it has a different electronic structure associated with very different magnetic properties (small-moment antiferromagnetism versus large-moment ferromagnetism) and a lower lattice parameter. It should be considered a new mineral for which we suggest the name antitaenite. We further propose that in the meteorites γLS always occurs in a fine epitaxial intergrowth with tetrataenite (atomically ordered FeNi). This resolves outstanding difficulties in meteoritic and particle-irradiated Fe-Ni metallurgy.

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