Abstract Nanostructured niobium nitride was synthesized through a solid-gas reaction in an atmosphere of nitrogen and hydrogen using an oxalic niobium precursor. Crystal phases evolution throughout the reactive processes were evaluated using X-Ray Diffraction, reaction parameters modifications were performed in isotherm time, gas flow, and precursors’ mass. It was verified the synthesis of a stable NbN material with a hexagonal structure under the following conditions: 1g of precursor, 300 min of isotherm at 1100 °C and, the gas flow of N2 = 40% (v/v), and H2 = 60% (v/v). The increase in gas phase flow and the decrease of solid load favored the process, and a pure and single-phase powder was obtained. This set indicates the importance of physical resistance in the fluid-particle interaction process. Under these conditions, the solid obtained had a crystallite size of 30 - 50 nm.

The present paper's objective was to synthesize and characterize both the oxalic niobium precursor (NH4)3NbO(C2O4)3.H2O, and the product of its doping with Cu and calcining, CuNb2O6. In order to obtain the niobium precursor, commercially available niobium oxide (Nb2O5) was subject to fusion with potassium bisulfate (KHSO4). Once leached with water, the powder was complexed with oxalic acid and ammonium oxalate. The as produced material was manually mixed with copper nitrate Cu(NO3)2.2H2O (25% Cu molar) and calcined at 1000°C in a muffle furnace. CuNb2O6 was then obtained. The precursor was characterized by XRD, SEM, FT-IR, XRF, TG/DTG. The calcination product was characterized by XRD, XRF and SEM. Results show that single phase CuNb2O6 could be obtained by this method without Nb2O5 contamination.