掺杂MoO_3对Ce_(0.8)Nd_(0.2)O_(1.9)固体电解质结构与电性能的影响

Effects of MoO_3-Dopant on the Microstructure and Electrical Conductivity of Ce_(0.8)Nd_(0.2)O_(1.9)

采用溶胶凝胶方法将过渡金属氧化物MoO3加入到Ce0.8Nd0.2O1.9体系中,讨论MoO3的掺杂对微观结构及电性能的影响。通过X-射线衍射(XRD)、场发射扫描电镜(FE-SEM)等手段对氧化物进行结构表征,交流阻抗谱测试电性能。结果表明:烧结过程中MoO3在晶粒边缘形成液相,增加了晶粒间浸润性,晶粒间位置重排并接触,晶界滑移加快,促使材料致密化,晶界体积分数降低;总电导率和晶界电导率因晶界电阻减少而提高。600℃时,NDC的σt和σgb分别为6.42×10-3和2.03×10-2S·cm-1,加入MoO3后材料的σt提高约1.5倍,σgb提高约4倍。MoO3是NDC体系理想的烧结助剂。

The Ce0.8Nd0.2O1.9 were prepared through modified sol-gel method. It is systematically discussed that the effects of MoO3 doping on the structures and conductivity. The structures of the samples were characterized by means of X-ray diffraction （XRD）, and field-emission scanning electron microscopy （FESEM）. The ionic conductivity was systematically studied in air using an AC impedance spectroscopy. The results showed that the MoO3 can form a thin amorphous film around particles, which reduces the interparticle friction, and increases the contact area of particles in a compact solid. And this promotes mass diffusivity of the matrix, thus enhancing the further increase in densification and decrease in the volume fraction of grain boundary. The total and grain boundary conductivity increases due to the decreasing of the grain boundary resistance. It shows that the solution Ce0.8Nd0.2O1.9 doped with MoO3 was detected to be with the higher conductivity （σt=6.42× 10^-3 S· cm^-1, σgb=2.03× 10^-2 S· cm^-1 at 600 ℃ ）, which is more or less one point five times of σt and four times of σgb for sample without MoO3 doping respectively. MoO3 is the perfect sintering aids of the NDC system.