Kim, C.S. Park, Kyoung Won Tuller, H.L. 2024-01-19T14:33:13Z 2024-01-19T14:33:13Z 2021-09-02 2021-06 1359-6454 https://pubs.kist.re.kr/handle/201004/116962 Fundamental understanding of materials properties requires the study and development of defect chemical reactions and models. In-depth analysis of the defect chemistry of metal oxides, however, has generally been limited to the oxygen deficient regime. Here, we present a defect chemical study covering both oxygen deficient and excess regimes using donor-doped layered cuprate (La1.85Ce0.15CuO4+δ) thin films over a wide range of oxygen activity levels. Unlike perovskite- or fluorite-structured oxides, layered cuprates can readily accommodate oxygen interstitials as well as vacancies. The scope of the defect chemical study was extended to include highly oxidizing conditions equivalent to many orders of magnitude higher oxygen activities than ambient pressure. This was achieved by electrochemical pumping of oxygen through an ionically conducting yttria-stabilized zirconia (YSZ) substrate with oxygen nonstoichiometry values derived from in situ chemical capacitance measurements between 500°C and 650°C. The defect chemical model was correlated with in-plane conductivity at different oxygen pumping levels in the temperature regime of 275~350°C. Thermodynamic parameters - thermal band gap, enthalpy of reduction and anion Frenkel-pair formation - were derived from a defect chemical analysis. The approach taken here can be extended to other layered oxides and opens up the possibility of accessing much broader oxygen activity limits and thereby an extended range of defect regimes and neighboring phases. ？ 2021 English Acta Materialia Inc Electrochemically controlled defect chemistry: From oxygen excess to deficiency Article 10.1016/j.actamat.2021.116866 1 Acta Materialia, v.211 Acta Materialia 211 N scie scopus 000663197000001 2-s2.0-85104786806 Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Materials Science Metallurgy & Metallurgical Engineering Article Capacitance measurement Cerium compounds Chemical analysis Copper compounds Defects Energy gap Fluorspar Lanthanum compounds Materials properties Oxygen Perovskite Yttria stabilized zirconia Yttrium metallography Yttrium oxide Zirconia Electrochemical pumping In-plane conductivity Oxidizing conditions Oxygen interstitials Oxygen non-stoichiometry Temperature regimes Thermodynamic parameter Yttria-stabilized zirconias (YSZ) Oxygen vacancies Chemical capacitance Cuprates Defect chemistry Electrochemistry Solid state ionics Thin films