Metastable phase formation during chemical vapor deposition of niobium-germanium films

Regularities of different metastable phase formation during chemical vapor deposition of niobium-germanium coatings were investigated. These coatings were deposited on wire and band metal substrates by method of chemical transport reactions with the use of iodine as transporting agent. It was shown that it was possible to deposite the metastable Nb5Ge3 phase with structure of T2 type and X phase with cubic structure and hypothetical Nb2Ge composition during iodide process using Nb3Ge alloy as initial material together with phases existing at state diagram. Metastable T2 and X phases are formed only at high total pressure (more 250-500 Pa) and deposition rate less 1 μm/min. Coatings on the base of Nb3Ge with germanium content from 11 to 23 at.% were obtained