Modification of Ag-doped BaTiO3 powders through La gaseous penetration route

The Ag-doped BaTiO3 (BATO) polycrystalline powders were fabricated by Sol-Gel method. Further modification by rare earth La was done through gaseous penetration route. Changes in constitution, structure, and electrical conductivity before and after modification of Ag and La were characterized. The acceptor dopant Ag owned the ability to decrease the resistivity of the doping samples from 4.30×109 Ω·m to 6.14×105 Ω·m where the resistivity fell by 4 orders of magnitude when the Ag doping ratio was 0.10%. And more doping of Ag enhanced the resistivity dramatically even beyond 2.0×107 Ω·m. Yet, gaseous penetration of La successively reduced the resistivity of BATO to the lowest point of 2.45×105 Ω·m. XRD analysis indicated that the doping process of Ag did not change the perovskite structure and main phases of the powders. However, new compound BaLa2O4 generated from complex reactions during the penetration process, which manifested that La3+ penetrated into the crystal lattices in the form of substituting the Ti4+ site. And this substitution strengthened the Ti-O bond, which led to the inhibition of blue shift in FTIR spectrum caused by doping of Ag. The morphology of La penetrated BATO powders detected by SEM and EDAX suggested that La did penetrate into the powders and this penetration process progressed the partly sintering of the powders which is in favor of the conductivity.