Phase, microstructure evolution, and periodic density functional theory study of reduction and nitridation of V2O3 with clean ammonia gas.

[Display omitted] • Reduction and nitridation of V 2 O 3 with clean ammonia gas is investigated. • The phase and microstructure evolution are revealed. • A DFT study systematically reveals the adsorption of NH x and H on the V 2 O 3 (0001) surface. • The reaction route is as follows: V 2 O 3 → VN x O 1– x → VN. Vanadium nitride (VN) has a wide range of application because of its excellent properties, which include high hardness, outstanding wear resistance, and good electrical conductivity. This study investigated the mechanism for the reduction and nitridation of V 2 O 3 with clean ammonia gas, using both experimental and density functional theory (DFT) studies. The experimental results indicated that V 2 O 3 could easily be converted to VN in an ammonia atmosphere at 500–800 °C. The reaction pathway to form VN was V 2 O 3 → VN x O 1– x → VN. Increasing the reaction temperature was conducive to an increase in the N content of VN x O 1– x. A DFT study systematically revealed the adsorption of NH x and H on the V 2 O 3 (0001) surface. The results showed that with the dissociation of NH 3 , its adsorption energy on the surface of vanadium oxide became higher. The whole reaction process could be divided into NH 3 decomposition on the surface and the formation of H 2 O(g). Both of these were endothermic reactions, and the reaction step of generating H 2 O(g) needed a higher temperature. The bonding of V 3c –N facilitated the desorption of O 3c atoms to form H 2 O(g), which explained why VN can be prepared by the reaction of NH 3 and V 2 O 3. [ABSTRACT FROM AUTHOR]