Sintering and electrical behavior of ZrP2O7-CeP2O7 solid solutions Zr1-xCexP2O7; x=0-0.2 and (Zr0.92Y0.08)(1-y)CeyP2O7; y=0-0.1 for application as electrolyte in intermediate temperature fuel cells

Abstract

ZrP2O7-CeP2O7 solid solutions, Zr1-xCexP2O7; x=0-0.2 and (Zr0.92Y0.08)(1-y)CeyP2O7; y=0-0.1, were prepared by partially replacing Zr4+ with Ce4+ and its effect on the phase composition, sintering behavior, microstructure, and ionic conductivity is analyzed. Ce4+-doped specimens showed improved sintering behavior due to the partial reduction of Ce4+ to Ce3+, as confirmed by X-ray photoelectron spectroscopy (XPS). In unhumidified atmosphere, the electrical conductivity of Zr1-xCexP2O7 increased with increasing cerium content, which can be attributed to the increase in densification and formation of oxygen vacancies due to the partial reduction of Ce4+ to Ce3+. For (Zr0.92Y0.08)(1-y)CeyP2O7; y=0-0.1 specimens, the electrical conductivity increased 4 orders of magnitude during humidification in air (pH2O=0.12atm). At 80 degrees C, specimen (Zr0.92Y0.08)(0.9)Ce0.1P2O7 (ZYCP10) showed a maximum of 1.72x10(-2)Scm(-1) which decreased sharply at 100 degrees C. Furthermore, Zr0.92Y0.08P2O7 (ZYP), (Zr0.92Y0.08)(0.95)Ce0.05P2O7 (ZYCP5), and ZYCP10 specimens humidified at 160 degrees C showed the maximum conductivity of 1.04x10(-3), 1.32x10(-3), and 8.09x10(-3) Scm(-1), respectively, at 190 degrees C.