| A series of new oxygen ion conductor solid electrolytes, including ZrO2-Ta2O5,Y2O3-Ta2O5, Y2O3-ZrO2-Ta2O5以åŠRO-M2O3-ZrO2-Ta2O5(R=Ca,Mg, M=Y,Nd,Pr,Sc) systems are studied in this paper . Solid electrolytes of different chemical composition with low thermal expansion and high oxygen ion conductivity are prepared by high-temperature sinter technology. The ion conductivity, thermal expansibility, expansion mechanics, micostructure morphology are investigated by insulated resistance device, thermal dilatometer (TD), X-ray diffraction (XRD). Using the TREOR90 software, the X-ray pattern of ZrO2-Ta2O5 and Y2O3-ZrO2-Ta2O5 systems are indexed. The crystal structure type of them are confirmed, and the unit-cell parameters are calculated. It discusses the dependence relationship of the conductivity and thermal expansion coefficient on the composition. Research results indicate as follow:ZrTaxO2+2.5x system is a kind of oxygen ion solid electrolyte with high conductivity at high temperature and low thermal expansibility. The conductance increases first and then reduces fluctuantly dependence on increasing x , and it changes from 0.17×10-4 to 5.27×10-4s/cm. The thermal expansion coefficient reduces from 5.364×10-6 to 1.467×10-6K-1 when x increases. The higher is the conductivity, the lower is the thermal expansion coefficient when x changes near 1.3. The conductivity of ZrTa1.3O5.25 is the highest at 820℃, 5.27×10-4s/cm. Its thermal expansion coefficient is 2.806×10-6K-1. When x is 3.0, thermal expansion coefficient of ZrTa3O9.5 is the lowest, 1.467×10-6K-1. Crystal structure of ZrTaxO2+2.5x system is orthogonal. The crystal structure resembles ZrV2O7's. Low thermal expansibility is caused by bridge oxygen ion horizontal libration.Conductivity of YTaxO1.5+2.5x system changes between 3.02×10-6 and 31×10-6s/cm at 820℃. Thermal expansion coefficient changes between 9.046×10-6 and 9.995×10-6K-1. Conductivity and thermal expansion coefficient of YxZr1-xTa2O7-0.5x and Y0.08Zr0.92+xTa2-xO6.96-0.5x are: 7.87×10-6～77.98×10-6 s/cm at 820℃, 0.59×10-6～3.99×10-6 s/cm at 740℃and 2.23×10-6～3.71×10-6K-1, 2.05×10-6～4.17×10-6K-1 respectively.Conductivity of CaxY1-xZr0.15Ta1.85O6.425-0.5x changes between 0.42×10-4 and 1.82×10-4s/cm. The thermal expansion coefficient of Mg0.15Sc0.425Y0.425Zr0.15Ta1.85O6.5 is low, 5.87×10-6K-1. |
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