Zinc nitride

Zinc nitride (Zn3N2) is an inorganic compound of zinc and nitrogen, usually obtained as (blue)grey crystals. It is a semiconductor. In pure form, it has the anti-bixbyite structure.

Chemical properties
Zinc nitride can be obtained by thermally decomposing zincamide (zinc diamine) in an anaerobic environment, at temperatures in excess of 200 °C. The by-product of the reaction is ammonia. "3 Zn(NH2)2 → Zn3N2 + 4 NH3"

It can also be formed by heating zinc to 600 °C in a current of ammonia; the by-product is hydrogen gas. "3 Zn + 2 NH3 → Zn3N2 + 3 H2" The decomposition of Zinc Nitride into the elements at the same temperature is a competing reaction. At 700 °C Zinc Nitride decomposes. It has also been made by producing an electric discharge between zinc electrodes in a nitrogen atmosphere. Thin films have been produced by chemical vapour deposition of Bis(bis(trimethylsilyl)amido]zinc with ammonia gas onto silica or ZnO coated alumina at 275 to 410 °C.

The crystal structure is anti-isomorphous with Manganese(III) oxide. (bixbyite). The heat of formation is c. 24 kcal per mol. It is a semiconductor with a reported bandgap of c. 3.2eV, however, a thin zinc nitride film prepared by electrolysis of molten salt mixture containing Li3N with a zinc electrode showed a band-gap of 1.01 eV.

Zinc nitride reacts violently with water to form ammonia and zinc oxide. "Zn3N2 + 3 H2O → 3 ZnO + 2 NH3"

Zinc nitride reacts with lithium (produced in an electrochemical cell) by insertion. The initial reaction is the irreversible conversion into LiZn in a matrix of beta-Li3N. These products then can be converted reversibly and electrochemically into LiZnN and metallic Zn.