Fe2n

Fe2N is a binary compound consisting of iron and nitrogen in roughly a 2:1 atomic ratio. It is one of several iron-nitrogen phases that can form in nitrogen-rich environments or during the nitriding of iron-containing materials. In practice, Fe2N is often reported as a non-stoichiometric phase, with compositions described as Fe2N±δ in which the exact nitrogen content can vary with synthesis conditions.

Structure and polymorphism are characteristic of iron nitrides. Fe2N has been reported to occur in more than one crystal structure depending on temperature, pressure, and preparation method. In general, nitrogen atoms occupy interstitial sites within an iron lattice, producing a hard, dense nitride phase. The precise lattice arrangement can differ from one study to another, and several polymorphs have been described in the literature.

Synthesis of Fe2N typically occurs under nitrogen-rich conditions. Common routes include nitriding of iron or steel in controlled nitrogen or ammonia atmospheres at elevated temperatures, plasma nitriding, and certain deposition techniques such as reactive sputtering or chemical vapor deposition in nitrogen-containing environments. Fe2N is often considered metastable relative to other iron nitrides such as Fe3N and Fe4N, and its presence can depend on temperature, nitrogen activity, and material history.

Properties of Fe2N generally include increased hardness and wear resistance associated with nitride formation, along with magnetic behavior inherited from iron. Magnetic and mechanical properties can vary with exact composition and structure. Stability ranges and transformations to other iron-nitrogen phases are active areas of study in materials science and surface engineering.

Related compounds include Fe3N, Fe4N, and FeN, which together span the broader iron-nitride system.