Effect of carbon content on preparation of vanadium carbide nanopowders by the carbonization of the precursor

摘要

Vanadiunm carbide (V_8C_7) nanopowders were prepared by the solution-derived precursor method, ammonium vanadate (NH_4VO_3) and glucose (C6H12O6) were used as raw materials. The samples were characterized by TG-DTA, XRD and SEM. The results show that the weight of the sample reduces rapidly before 600°C (about 25 wt.%), but it changes very slowly (about 1.0 wt.%) after 600°C. The DTA curve mainly includes 5 endothermic peaks and an exothermic peak which are corresponding to the peaks of 110°C, 300°C, 348°C, 677°C, 1000°C and 509°C, respectively. When the carbon content between 24 wt.% and 30 wt.%, the samples mainly consist of V_2O_3 and VC_(1-X) (1-X = 0.66-0.88). When the carbon content is 32 wt.%, the sample includes a main phase (V_8C_7) and a second phase (V_2O_3). When the carbon content reaches to 36 wt.%, the single-phase V_8C_7 powder can be obtained. The SEM results show that major powders exhibit good dispersion and are mainly composed of particles with a mean diameter of ～200 nm.