Conductivity of VO2-based ceramics

The electrical conductivity in the system VO2-VPG-Cu-SnO2 (VPG-vanadium phosphate glass) was investigated for ceramics compositions (80-y)VO2-15VPG-5Cu-ySnO2 with SnO2 content y in the interval 0 wt.% < = y < = 70 wt.%. The conductivity change of near 10 caused by semiconductor-metal phase transition in VO2 crystallites was observed when SnO2 content is in the interval 0 wt.% < = y < = 55 wt.%. The temperature of the abrupt change in conductivity Tt has a value within 69-74 ∘C for different ceramics compositions. The abrupt change in conductivity is absent, when y > 65 wt.%. When SnO2 content has changed from 0 wt.% to 70 wt.% the ceramics conductivity diminishes by 10 times. As shown, the percolation theory results obtained for the mixture of conductive and non-conducting components may be used for the description of conductivity in VO2-based ceramics. Vanadium dioxide as the conductive component gives the main contribution into ceramics conductivity when VO2 volume content exceeds the value corresponding to the percolation threshold ~25 vol.%.