NaFeO2

NaFeO2 is an inorganic compound consisting of sodium, iron, and oxide ions, with iron in the +3 oxidation state. In solid form it is typically described as a layered sodium iron oxide. The material is primarily of interest in solid-state chemistry and materials science as a model for layered transition-metal oxides.

Structurally, NaFeO2 adopts a layered oxide framework in which sheets of FeO6 octahedra are stacked with interleaved layers containing Na+ ions. This arrangement is related to the delafossite family of ABO2 compounds and gives rise to two-dimensional pathways for ion transport. Iron in NaFeO2 is high-spin Fe3+ in an octahedral environment, and the compound is typically insulating or a poor conductor at room temperature.

Synthesis and occurrence: NaFeO2 is not common as a naturally occurring mineral and is ordinarily prepared synthetically through high-temperature solid-state reactions starting from sodium sources and iron oxide. It can be obtained as a single-phase material under carefully controlled conditions, and is sometimes quenched to preserve the layered structure.

Applications and research: The material has attracted interest as a potential electrode material for sodium-ion batteries due to its layered structure, which can accommodate reversible extraction and insertion of Na+. Research explores substitutions and dopants to improve electronic conductivity and cycling stability, as well as using NaFeO2 as a precursor to other iron-oxide phases.

See also: LiFeO2, CuFeO2, and other delafossite and layered oxide compounds.