Cu incorporated perovskite Na0.5Bi0.5TiO3 oxygen-defect conductor as NO2 sensor using CuO sensitive electrode

摘要

In this work, perovskite Na0.5Bi0.5TiO3 is applied as oxygen-defect conductor of NO2 sensor fabricated with CuO as the sensing electrode and Pt as reference electrode. Transition metal ion Cu2+ serves as a dopant of Na0.5Bi0.5TiO3 at B site in view of its dual functions in both creating as many oxygen vacancies as possible and extending the length of the triple phase boundaries together with CuO sensing electrode. The phase transformation from the cubic to rhombohedral phase occurs in the process of increasing Cu2+ contents, resulting in greater lattice distortion and thus generating more oxygen vacancies. The expansion of the lattice volume and the overflowed Bi2O3 promote oxygen hopping in the [BO6](proportional to) chains of the solid electrolyte. The electrochemical results indicate that the Na0.5Bi0.5Ti0.85Cu0.15O3-delta sensor exhibits excellent response-recovery characteristics with high sensitivity (24.49 nA/ppm) upon exposed to 500 ppm NO2 at 500 degrees C. The possible coexistent gases affect little on the response current of the sensor towards NO2 gas. The long-term stability measurement illustrates that there is only a slight 1.36 mu A drop in response current value after aging storage for one and a half months. The performances of the sensors based on non-rare-earth Cu-doped Na0.5Bi0.5TiO3 solid electrolytes exhibit the better-off application prospect with low cost at low-medium temperature.