Phase evolution during synthesis of vanadium carbide (V8C7) nanopowders by thermal processing of the precursor

The phase and structure evolution during synthesis of vanadium carbide (V₈C₇) nanopowders by thermal processing of the precursor were investigated using X-ray diffraction (XRD). The morphology of the reactant was characterized by transmission electron microscopy (TEM). Simultaneous thermogravimetric and differential thermal analysis (TG-DTA) were made on the precursor. The results indicate phase evolution sequences are NH₄VO₃→V₂O₅→VO₂→V₅O₉+V₄O₇→V₂O₃→VC_1−X→V₈C₇. The single phase V₈C₇ powders can be prepared at ∼1100 °C for 1 h, and the powders show good dispersion and are mainly composed of uniformly sized spherical particles with the majority diameters of 20-50 nm.