Sol-gel法制备La_(9.33)Si_6O_(26)及其导电性能

Preparation of La_(9.33)Si_6O_(26) by sol-gel process and its electrical properties

通过溶胶-凝胶(sol-gel)法制备磷灰石型固体电解质La9.33 Si6O26,考察sol-gel过程中水硅摩尔比(n(H2O)/n(Si))、醇硅体积比(V(C2H5OH)/V(Si))和pH等制备参数对溶胶性质的影响,并采用正交设计确定了最佳制备条件。X线衍射(XRD)分析显示,在n(H2O)/n(Si)=10、V(C2H5OH)/V(Si)=5、pH=2的最佳制备条件下可获得单相的磷灰石型晶体。试样在1 550℃烧结4 h后的相对密度为93.9%,其800℃时的氧离子电导率高达5.50×10-3 S/cm,电导活化能为0.86 eV,室温至800℃测得试样的热膨胀系数为9.3×10-6 K-1,与普遍使用的电极材料之间具有较好的热匹配性。

The electrolyte La9.33Si6O26 with apatite structure was synthesized by sol-gel process.The effect of parameters,such as n（H2O）/n（Si）,V（C2H5OH）/V（Si） and pH value on the gel formation was studied and the optimum parameters were determined by orthogonal experiments.X-ray diffraction（XRD） data analysis showed that pure apatite phase was formed when n（H2O）/n（Si）=10,V（C2H5OH）/V（Si）=5,pH=2.After sintering at 1 550 ℃ for 4 h,the relative density of the sintered sample was 93.9%.The ionic conductivity reached 5.50×10-3 S/cm at 800 ℃,and the activation energy was 0.86 eV.The thermal expansion coefficient（TEC） of the sintered sample was 9.3×10-6 K-1 from room temperature to 800 ℃,thus it had a good match with the demonstration electrode.