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摘要
A new route to synthesize pure VN nano-powder from the ammonolysis of the special precursor, (NH4) (5)[(VO)(6)(CO3)(4)(OH)(9)] . 10H(2)O (NVCO) is described. The violet polycrystalline NVCO was simply synthesized by solution reaction using V2O5, HCl, N2H4 . 2HCl and NH4HCO3 as the starting materials. The thermolysis process of the NVCO was investigated by TGA and DTA in a NH3 flow. The TG data indicated that the mass loss of the NVCO was about 58% before V2O3 forms at 630degreesC and released fast large amount of H2O, CO2 and NH3 gases, causing that the particles of the NVCO and intermediates were split and atomized strongly during the ammonolysis, thus generating VN nanopowders. The effect of various ammonlysis conditions on nitridation rate of products was studied in detail under tube furnace condition. The result of elemental analysis identified that 95.33% VN was obtained at 850degreesC for 12h. The result of X-ray diffraction showed that the lattice parameter of the powder was a = 0.4139 (0) run, according with a = 0.413916 (4) nm of ASTM. Scanning electron microscopic micrographs show that the particles of VN powder are quasi-spherical about 30nm in size with more homogeneous distribution. Advantage of this synthesis route is: (1) NVCO is easily synthesized; (2) the ammonolysis condition are milder; (3) it is not necessary to use very precise temperature-programmed reaction controls; (4) the particles of nano-VN powder are quasi-spherical and more homogeneous distribution.
- 出版日期2003-10
- 单位中山大学
