Preparation and characterization of (V1−xAlx)2O3 nano-grain ceramics by chemical doping route

(V1−xAlx)2O3 nano-grain ceramics have been prepared successfully for the first time by sintering (V1−xAlx)2O3 nano-powders obtained from a chemical doping route under a H2 atmosphere at 1373-1623 K for 15-60 min. The SEM micrographs show that the nano-powders obtained by pyrolyzing Al-doped precursors in H2 at 723-823 K are more suitable as precursors for ceramics. The AFM micrographs show that the obtained ceramics have a hierarchical structure: the agglomerates in ceramics are about 1-2 μm in size, and the agglomerates are composed of spherical particles with diameters of about 30-40 nm. The result of resistivity measurement of (V1−xAlx)2O3 nano-grain ceramics confirms that the nano-crystal boundaries in ceramics not only could eliminate effectively the thermo-stress during preparation process but also may be a good electric conductor. The nano-grain ceramics have low room temperature resistivity and exhibit good PTC property. The magnetic susceptibility result of the ceramics also exhibits the intrinsic phase transition property.