Synthesis of a soluble precursor possessing an Nb-N backbone structure and its pyrolytic conversion into niobium-based ceramics

Synthesis and pyrolysis of a soluble precursor possessing an Nb-N backbone structure were investigated. The precursor was prepared by aminolysis reaction of tetrakis(diethylamido)niobium with isopropylamine. The precursor was soluble in benzene, and had a polymeric structure possessing Nb-N-Nb imido-bridges. The precursor was pyrolyzed under NH₃-N₂ (at 600 °C for 2 h under NH₃ and subsequently at 1350 °C for 8 h under N₂) and Ar (at 1500 °C for 2 h) atmospheres. δ-NbN was obtained as a main crystalline phase after the pyrolysis of the precursor under NH₃-N₂, whereas pyrolysis of the precursor under Ar led to the formation of NbC as the only crystalline phase. More than 90% of niobium which was present in the precursor remained in both of the pyrolyzed products.