S.-J. Song

Defect Structure and n-Type Electrical Properties of SrCe0.95Eu0.05 O 3 − δ

The effect of defect structure on the electrical conductivity for Eu-doped SrCeO 3 was studied in a reducing range of P H 2 , P H 2 O , P O 2 . A defect model was derived and verified by computational simulation against bothelectrical conductivity data and Brouwer-type defect equilibria. At higher temperatures, part of the conductivity was due to oxygen vacancies and electrons. At low temperature, protonic conduction dominated. The measured total conductivity is proportional to P - 1 / 8 O 2 in the temperature range of 650-750°C, and to P - 1 / 6 O 2 at 800°C in wet atmospheres, because of a transition from ionic- to electronic-dominant conduction. The results agree with a derived defect model based on the equilibrium equation for the valence change of Eu ions between trivalent and divalent.

Electrical Properties of p-Type Electronic Defects in the Protonic Conductor SrCe[sub 0.95]Eu[sub 0.05]O[sub 3−δ]

The electrical properties of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} were studied as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500-800 C, and the partial conductivities of protons, holes, and oxygen vacancies were calculated from the proposed defect model. P-type conduction was dominant in an oxidative atmosphere. It was shown that, in a wet atmosphere, SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} is a mixed conductor of protons, holes, and oxygen ions. A conduction transition from protons to holes and/or oxygen ions was found as temperature increased. The calculated activation energy of oxygen ion transport was 0.67 eV; standard solution enthalpy of water dissolution was -164 kJ/mole, which is larger than that of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}}. The effect of dopants on the conduction mechanism is explained by a hopping mechanism.

Electrical Properties of p-Type Electronic Defects in the Protonic Conductor SrCe0.95Eu0.05 O 3 − δ

The electrical properties of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} were studied as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500-800 C, and the partial conductivities of protons, holes, and oxygen vacancies were calculated from the proposed defect model. P-type conduction was dominant in an oxidative atmosphere. It was shown that, in a wet atmosphere, SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} is a mixed conductor of protons, holes, and oxygen ions. A conduction transition from protons to holes and/or oxygen ions was found as temperature increased. The calculated activation energy of oxygen ion transport was 0.67 eV; standard solution enthalpy of water dissolution was -164 kJ/mole, which is larger than that of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}}. The effect of dopants on the conduction mechanism is explained by a hopping mechanism.

Electrical properties of p-type electronic defects in the protonic conductor SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-episilon}.

The electrical properties of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} were studied as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500-800 C, and the partial conductivities of protons, holes, and oxygen vacancies were calculated from the proposed defect model. P-type conduction was dominant in an oxidative atmosphere. It was shown that, in a wet atmosphere, SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}} is a mixed conductor of protons, holes, and oxygen ions. A conduction transition from protons to holes and/or oxygen ions was found as temperature increased. The calculated activation energy of oxygen ion transport was 0.67 eV; standard solution enthalpy of water dissolution was -164 kJ/mole, which is larger than that of SrCe{sub 0.95}Eu{sub 0.05}O{sub 3-{delta}}. The effect of dopants on the conduction mechanism is explained by a hopping mechanism.