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.