The effect of Cr dopant concentration on electrical property of (V1−xCrx)2O3 nano-grain ceramics

A series of (V1−xCrx)2O3 ceramics (x = 0.0035, 0.0053, 0.0060, 0.0083 and 0.0095) have been prepared by a chemical doping route. XRD patterns and the lattice parameters of all samples confirm that Cr(III) enter the V2O3 lattice. The AFM micrographs show that the obtained ceramics have a hierarchical structure: the agglomerates are about 1–2 μm in size consisting of spherical particles with diameters of about 65–85 nm. The result of resistivity measurement reveals that the ceramics with the dopant concentration range (0.0035 < x ≤ 0.0080) obtained at 1523 K for 45 min possess good PTC properties and their resistivity jump are in the range of 1.0 × 102–7.5 × 102. The good PTC effect is attributed to the nano-size grains and the hierarchical structure. It is found that the dopant concentration range is much narrower than that (0.005 < x < 0.018) in (V1−xCrx)2O3 micro-grain ceramics and single-crystals.