Defect Structure and Electrical Conductivities of <TEX>$SrCe_{0.95}Yb_{0.05}O_3$</TEX>

,; ,; ,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 37(3); 2000 > Article

Journal of the Korean Ceramic Society 2000;37(3): 271.

$SrCe_{0.95}Yb_{0.05}O_3$의 결함엄개와 전기전도 특성

최정식, 이도권, 유한일

서울대학교 재료공학부 고체이온공학연구실

Defect Structure and Electrical Conductivities of $SrCe_{0.95}Yb_{0.05}O_3$

ABSTRACT

5 m/o Yb-doped SrCeO3 proton conductor was prepared by a solid state reaction method and its total electriccal conductivity measured as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500~100$0^{circ}C$. From the total conductivity have been deconvoluted the partial conductivities of oxide ions, protons, and holes, respectively, on the basis of the defect model proposed. The equilibrium constant of hydrogen-dissolution reaction, proton concentration, and mobilities of oxygen vacancies and protons have subsequently been evaluated. It is verified that SrCe1-xYbxO3 is a mixed conductor of holes, protons and oxide ions and the proton conduction prevails as temperature decreases and water vapor pressure increases. The heat of water dissolution takes a representative value of $Delta$HoH=-(140$pm$20) kJ/mol-H2O, but tends to be less negative with increasing temperature. Migration enthalpies of proton and oxygen vacancy are extracted as 0.83$pm$0.10 eV and 0.81$pm$0.01 eV, respectively.

Key words: Proton conductors, $SrCe_{0.95}Yb_{0.05}O_3$, Defect structure, Partial electrical conductivity, Water dissolution, Migration enthalpy