Iron has five
nitrides observed at ambient conditions, Fe2N, Fe3N4, Fe4N, Fe7N3 and Fe16N2. They are
crystalline,
metallic solids.
Group 7 and
group 8transition metals form nitrides that decompose at relatively low temperatures – iron nitride, Fe2N decomposes with loss of molecular nitrogen at around 400 °C and formation of lower-nitrogen content iron nitrides. They are
insoluble in
water. At high pressure, stability and formation of new nitrogen-rich nitrides (N/Fe ratio equal or greater to one) were suggested[1] and later discovered. These include the FeN, FeN2 and FeN4 solids which become thermodynamically stable above 17.7 GPa, 72 GPa and 106 GPa, respectively.[2][3][4][5][6]
Health hazards
When heated to decomposition or exposed to humidity, iron nitride may emit toxic fumes of
ammonia. It is considered a moderate explosion hazard. Inhalation of iron nitride dust or powder may cause irritation to the respiratory system and possibly acute
iron poisoning or
pneumoconiosis.
^Laniel, Dominique; Dewaele, Agnès; Anzellini, Simone; Guignot, Nicolas (2018-02-05). "Study of the iron nitride FeN into the megabar regime". Journal of Alloys and Compounds. 733: 53–58.
doi:
10.1016/j.jallcom.2017.10.267.
ISSN0925-8388.
^Niwa, Ken; Terabe, Toshiki; Kato, Daiki; Takayama, Shin; Kato, Masahiko; Soda, Kazuo; Hasegawa, Masashi (2017-05-16). "Highly Coordinated Iron and Cobalt Nitrides Synthesized at High Pressures and High Temperatures". Inorganic Chemistry. 56 (11): 6410–6418.
doi:
10.1021/acs.inorgchem.7b00516.
ISSN0020-1669.
PMID28509545.
^Laniel, Dominique; Dewaele, Agnès; Garbarino, Gaston (2018-03-05). "High Pressure and High Temperature Synthesis of the Iron Pernitride FeN2". Inorganic Chemistry. 57 (11): 6245–6251.
doi:
10.1021/acs.inorgchem.7b03272.
ISSN0020-1669.
PMID29505253.