Formula Zn3N2 Density 6.22 g/cm³ | Molar mass 224.154 g/mol Appearance blue-gray cubic crystals | |
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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.
3Zn(NH2)2 → Zn3N2 + 4NH3
It can also be formed by heating zinc to 600 °C in a current of ammonia; the by-product is hydrogen gas.
3Zn + 2NH3 → Zn3N2 + 3H2
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. Thins 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 kilocalories (100 kJ) 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 + 3H2O → 3ZnO + 2NH3
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 electrochemicalically into LiZnN and metallic Zn.