Properties of Nitrides Prepared by the Ammonolysis of Magnesiothermic Niobium Powders

Resumo

We have studied the effects of the specific surface area of mesoporous magnesiothermic niobium powders and ammonolysis conditions on characteristics of the reaction products. Ammonolysis was carried out in the temperature range 400–800°C using powders with specific surface areas of 18, 83, and 123 m²/g. The results demonstrate that the ammonolysis of the powders with specific surface areas of 83 and 123 m²/g first leads to the formation of the NbON oxynitride, which then converts into NbN with a face-centered cubic lattice at a temperature of 700°C. The NbN nitride obtained by the ammonolysis of the powder with a specific surface area of 18 m²/g has a hexagonal close-packed structure.