Study On The Ion Conductivity Of Rare Earth Element Doped Ceria-based Electrolyte

As a member of the oxygen ion conductor solid electrolyte,cerium oxide-based materials have attracted great interest from researchers due to their excellent ionic conductivity at moderate temperatures?600⁸00^°C?.However,the large-scale application of this material needs to solve the following problems:in low oxygen partial pressure and high temperature,the reduction of Ce⁴⁺to Ce³⁺occurs in cerium ceria,resulting in electronic conductance;the influence of grain size on total conductivity is controversial;There is no uniform understanding of the effect of spark plasma sintering?SPS?on the ionic conductivity of cerium oxide-based materials.The conventional modification of cerium oxide mainly centers on single doping.In this paper,the following research is carried out on the above issues.The nanoscale SDC20 powder was prepared by co-precipitation method.The sample with a grain size of 128 nm to 533 nm was prepared by controlling the sintering temperature.The effect of grain size on conductivity was studied.The results show that within the range,the grain conductivity and the total grain boundary conductivity grow with the growth of the grain,and the specific conductivity of the grain decreases with the growth of the grain.The total conductivity of the sample eventually increases with the growth of the grain.The sample having a grain size of 233 nm sintered at1200^°C has the best conductivity that is 1.53×10^-2 S/cm at 650^°C.By controlling the heating process of SPS sintering,two kinds of SDC20electrolytes sintered at a different temperature at different heating rates were prepared.It was found that the faster the heating rate,the finer the crystal grains,at 950^°C,the average grain size of the sample sintered with 100^°C/min is?55 nm?,and the grain grows gradually with the increase of sintering temperature.At 1200^°C,the grain size of the sintered sample grows to 645 nm at a heating rate of 50^°C/min.In the conductivity test,the material sintered at a heating rate of 50^°C/min showed the best comprehensive performance,at 650^°C,the conductivity was 1.66×10^-2 S/cm,more than 100^°C/min sintered samples(1.23×10^-2 S/cm)and conventional sintered samples(1.53×10^-2 S/cm).The Samarium-gadolinium co-doped cerium-based powders?SGDCX,X=0²0?was prepared by the co-precipitation method.The XRD test showed that the obtained sample had a good cubic fluorite structure.Sample doped with 1 mol%Gd has the highest relative density of 97.14%.The conductivity test showed that with the increase of gadolinium content,the total conductivity increased first and then decreased.The electrolyte with gadolinium content of 1 mol%showed the highest conductivity,which was 1.59×10^-2 S/cm at 650^°C,and the activation energy was the lowest?0.75 eV?.