Effects Of Metal Oxides On Microstructure And Electrical Properties Of Ce_0.9Gd_0.1O_1.95 Electrolyte

Solid oxide fuel cell(SOFC)is an all solid-state energy conversion device operated at high temperatures with the advantage of high efficiency and little pollution. It has been considered as the "green power technology" in the21st century.Ceria-based solid solutions have been regarded as the most promising electrolytes for intermediate temperature SOFC (IT-SOFC). CeO2-based electrolyte materials is subject to more than1500-1600℃sintering temperature to obtain a higher density. One of the ways to improve the sintering properties of materials is to adding metal oxides as sintering aids to low the sintering temperature of the system.Therefore, the reduction deleterious grain boundary effects arising from SiO2impurity by adding the grain boundary scavenger, enhancing the total ionic conductivity, has become the focus of research in recent years.In this paper, we investigate the Gd2O3doped CeO2(CGO) system, different metal oxides would be used an effective sintering aid and a grain boundary scavenger for CGO system. We investigated the effects of sintering temperature and different metal oxides on the structures and electrical conductivities of high purity CGO and impurity CGO,we also got the optimum sintering aid and the best grain boundary scavenger. The main research contents of this paper are as follows:The high purity Ce0.9Gd0.1O1.95+1at.%metal oxides and the impurity Ce0.9Gd0.1O1.95+1at.%metal oxides+3000ppmSiO2were synthesized by sol-gel method.Their structures and ionic conductivities were characterized by X-ray Diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and electrochemical impedance spectroscopy (EIS). The results showed that:(1)In the high purity system,all the samples1200℃sintering for6h enhanced densification obviously. The total ionic conductivities of the samples adding MnO2、CaO and MgO as sintering aids increased,in which the total ionic conductivity of sample added MgO is maximum. The total ionic conductivity is3.185S·m-1at600℃(2) In the impurity system,all the samples1200℃sintering for6h enhanced densification obviously. The total ionic conductivities of the samples adding Fe2O3、CuO and CaO are higher than the high purity systems. The results suggest the addition of small amount of CaO could be used as sintering additive and grain boundary scavenger for the system of CGOSi at the same time.