Preparation and electrical property of CaZr0.7M0.3O3 (M = Fe, Cr and Co) dense diffusion barrier for application in limiting current oxygen sensor

(M = Fe, Cr and Co) doped CaZrO3, CaZr0.7M0.3O3 (M = Fe, Cr and Co), was synthesized by solid state reaction method. Crystalline structure, microstructures, electronic conductivity, total conductivity and sensing performance were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Hebb-Wagner, DC van der Pauw and voltammetry method, respectively. XRD measurements show that the CaZr0.7M0.3O3 (M = Fe, Cr and Co) samples belong to an orthorhombic perovskite structure. SEM measurements show that the CaZr0.7M0.3O3 (M = Fe, Cr and Co) samples have fine grains with average grain size of 0.5-2 μm. Electrical property measurements show that the CaZr0.7Fe0.3O3 and CaZr0.7Cr0.3O3 samples have the highest electronic conductivity and total conductivity in air, respectively. Sensing performance measurements show that limiting current-type oxygen sensors with 9YSZ solid electrolyte and CaZr0.7M0.3O3 dense diffusion barrier exhibit good limiting current (IL) plateau. Log IL depends linearly on 1000/T. IL depends linearly on oxygen partial pressure.