Study On Double-doped Ceria-Based Solid Electrolyte

For the study of mature zirconia-based solid electrolyte material,its working temperature is usually at 800-1000℃,which makes zirconia-based electrolyte materials have poor stability,thermal expansion coefficient mismatch and difficult issues such as electrode sintering occurs in practical applications.Ceria-based electrolyte materials belong to the low-temperature materials,which can avoid a series of problems caused by high temperature operation effectively.In order to improve the electrical properties of ceria-based electrolyte materials,low-doped ions become the main research methods.Doped ceria-based solid electrolytes were prepared by Solid-phase synthesis method.The effect of tow double doping systems of CeO2 with Yb3+ and Gd3+ and CeO2 with Ce3+ and Gd3+ simultaneously on the phase,morphology,sintering properties and electrical properties was investigated.In order to illustrate explicitly the impact of ions doped on CeO2 solid electrolyte,the study of Yb3+,Gd3+and Ce3+doped alone as control experiments was set up.The single cubic fluorite structure was found after doping these oxides.Appearance and microstrUcture were analyzed by the Scanning electron microscopy(SEM).It showed that the doped trivalent cations had entered into the ceria structure uniformly,and changed the lattice structure of CeO2.Due to different doping ion types and amounts,the dense of doped ceria-based solid electrolytes was slightly different,density of the sample doped with Gd3+ and Yb3+ was similar,and the relative density was above 90%,however density of the sample doped with Ce3+ was relatively poor.The electrical properties of the doped samples was characterized by AC impedance technique,the test results showed that the impedance of all samples tested was decreased as the rise of temperature,and the impedance of all samples was reduced as the increase of the ions doping amount,the samples had the minimum impedance value when the ions doping amount was in the maximum amount.The conductivity of the samples increased with increasing temperature,which indicated that the eonductivity of the samples was mainly ionic conductivity,and in this proeess,to improve the conductivity of the samples mainly by increasing the function of the grain boundary conductivity.In the systems of Yb3+,Gd3+ and Ce3+ doped alone,electrical properties of Yb3+ doped alone was best and electrical properties of Ce3+doped alone was worst.In the tow double doping systems of CeO2 with Yb3+ and Gd3+ and CeO2 with Ce3+ and Gd3+,electrical properties of Yb3+ doped was better.Yb3+ and Gd3+ double doped samples had optimal performance in all doping samples,and ionic conductivity of samples had the maximum value which was 4.4×10-4S·cm-1 when the mount of Yb3+ was 4mol%and the mount of Gd3+ was 6mol%.Compared with ionic conductivity of 10mol%Gd3+ doped CeO2 solid electrolyte material,Yb3+ doped improved the conductivity of the samples about 3 times,and played a important role on ceria electrolyte to improve the electrical properties of the material,thereby determining the ratio of 4mol%Yb3+ and 6mol%Gd3+ was the optimal doping ratio of doped CeO2 solid electrolyte material.