Synthesis and electrical properties of tungsten-doped vanadium dioxide nanopowders by thermolysis

Tungsten-doped vanadium dioxide (VO2) nanopowders were synthesized by thermolysis of (NH4)(5)[(VO)(6)-(CO3)(4)(OH)(9)](.)10H(2)O at low temperature with, to the best of our knowledge, active white powdery tungstic acid (WPTA) used as a substitutional dopant for the first time. The change in electrical resistance due to the semiconductor-metal transition was measured from -5 to 150 degrees C by the four-probe method. Differential scanning calorimetry and the resistance-temperature curve of the nanopowders indicated that the phase transition temperature Of VO2 powders was 67.15 degrees C, but for W-doped VO2, the temperature was reduced to 26.46 degrees C. The results indicated that WPTA was found to be exceptionally effective as a dopant for reducing the transition temperature.