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

Abstract

(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.