Investigation of Ti-modified BaBiNb5O15 oxide ion conductor prepared by two-step sintering method.

Ti-modified BaBiNb_0.95Ti_0.05O_15-δ (BBN-Ti5-TS) oxygen ion conductors with tungsten bronze structure were prepared by solid-phase reaction and two-step sintering-assisted sintering method. The electrical conductivity and oxygen ion diffusion of the Ti-modified BaBiNb₅O₁₅ (BBN) specimen were investigated. Both the grain conductivity and total conductivity of the BBN-Ti5-TS specimen are enhanced relative to the BBN compound. At 623 K, the BBN-Ti5-TS specimen grain conductivity can get up to 1.28 × 10^–4 S/cm, half an order of magnitude higher of the pristine BBN specimen. A relaxation peak associated with thermal activation was observed in the BBN-Ti5-TS specimen with a relaxation activation energy parameter of E = 0.44 eV. The value is slightly lower than the activation energy of oxygen ion migration in the parent compound. Combining the relaxation parameter and structural analysis, the titanium doping and two-step sintering-assisted sintering can reduce the energy barrier for oxygen ion diffusion to a certain extent. Compared with the BBN specimen, the lower oxygen diffusion activation energy and smaller grain size are the main reasons for the significant increase in the conductivity of the BBN-Ti5-TS compound. [ABSTRACT FROM AUTHOR]