A dense diffusion barrier limiting current oxygen sensor for detecting full concentration range

Although the limiting current-type oxygen sensors based on dense diffusion barriers have been developed for detecting oxygen concentration in harsh exhaust environments, their oxygen concentration measuring range is far below that of the sensors based on porous diffusion barriers, which can be improved through using electrochemically stable mixed oxide-ion/electron conductor. Here, we prepared a new family of mixed oxide-ion/ electron conductor by partial substitution of Ta for Nb at B-site in perovskite AgNbO3 under hydrothermal conditions. Among the investigated compositions, AgTa0.5Nb0.5O2.52 (ATN) exhibits oxide-ion conductivities of 6.7x10(-5) (450 degrees C) to 1.1x10(-3) S cm(-1) (850 degrees C) with activation energy of 0.59 eV and good electrochemical stability. Using it as dense diffusion barrier and 8YSZ (yttria-stabilized zirconia) as solid electrolyte, we demonstrate a novel dense diffusion barrier limiting current oxygen sensor that exhibited a linear relationship between the limiting current and oxygen concentration in range of 1.3-100 mol% at 800 degrees C at a low operating voltage. Furthermore, the sensor also shows good anti-interference ability for interfering CO2 gas and water vapor, acceptable long-term stability and poisoning robustness.