Preparation and characterization of niobium-doped barium titanate nanocrystalline powders and ceramics

Nb-doped BaTiO3 nanocrystalline powders and ceramics were prepared by a simple sol-gel process, which used H3[Nb(O2)4] as a precursor. The powders and ceramics were characterized by methods of XRD, SEM and TEM, while dielectric properties of the ceramics were also determined. The results indicated that the powders synthesized by sol-gel process were in nanometer scale, which were mainly composed of cubic BaTiO3 with small amount of BaCO3. After sintering, only BaTiO3 phase could be found and there was no evidence of a second phase. Compared to the traditional solid-state method, the sintering temperature of the ceramics prepared by sol-gel route was reduced obviously due to the good sinterability of nanopowders. And doped niobium could make Curie temperature shift to low temperature. Nb-doped BaTiO3 ceramics calcined at 1000 °C for 2 h and sintered at 1250 °C for 2 h had a regular microstructure with the maximal dielectric constant of 10,298. The methodology is a simple process with low cost, by which materials of BaTiO3 powders doped with high concentration of niobium, even up to 10 mol%, can be prepared.