Iron nitride

Iron nitride are inorganic chemical compounds of iron of the group of nitrides. There are Dieisennitrid Fe2N, Trieisennitrid Fe3N (more precisely Fe3N1 x), Tetraeisennitrid F4N and Stickstoffmartensit α '' - Fe16N2, and FeN are several known iron nitrides.

Occurrence

Tetraeisennitrid occurs in nature as the mineral Roaldit, Trieisennitrid as the mineral Siderazot.

Production and representation

Iron nitride can be obtained by reaction of iron with ammonia at 350 to 550 ° C. The resulting product is similar in composition to the formula Fe2N and represents the γ' - orthorhombic modification, which has a very narrow homogeneity range. Often, however, the occurrence of a hexagonal ε - phase with a smaller amount of nitrogen is observed approximately in accordance with a similar preparation Fe3N. The product upon heating in a vacuum at about 500 ° C with the release of nitrogen, first the ε - phase, then about Fe4N.

Properties

Iron nitrides are gray to black powder of metallartigem character. γ' - Fe2N ( CAS: 12023-20-0 ) has a density of 6.35 g · cm - 3, and has an orthorhombic crystal structure with space group Pm3m (A = 483 pm, 552 pm b = c = 442 pm ). The ε - modification Fe3N ( CAS: 12053-51-7 ) has a density of 7.36 g · cm - 3 and has a hexagonal crystal structure with space group P6322 (a = 270 pm, c = 437 pm ). Fe4N ( CAS: 12023-64-0 ) has a density of 6.57 g · cm -3 and has a cubic crystal structure with a close packing of the iron atoms and the space group P43m (a = 379.5 pm ).

Use

Iron nitrides formed during the surface treatment (hardening ) of steel. The corresponding process is called nitriding ( chemically correct: nitriding ) refers.