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Title: Atomically layer-by-layer diffusion of oxygen/hydrogen in highly epitaxial PrBaCo{sub 2}O{sub 5.5+δ} thin films

Single-crystalline epitaxial thin films of PrBaCo{sub 2}O{sub 5.5+δ} (PrBCO) were prepared, and their resistance R(t) under a switching flow of oxidizing and reducing gases were measured as a function of the gas flow time t in the temperature range of 200–800 °C. During the oxidation cycle under O{sub 2}, the PrBCO films exhibit fast oscillations in their dR(t)/dt vs. t plots, which reflect the oxidation processes, Co{sup 2+}/Co{sup 3+} → Co{sup 3+} and Co{sup 3+} → Co{sup 3+}/Co{sup 4+}, that the Co atoms of PrBCO undergo. Each oscillation consists of two peaks, with larger and smaller peaks representing the oxygen/hydrogen diffusion through the (BaO)(CoO{sub 2})(PrO)(CoO{sub 2}) layers of PrBCO via the oxygen-vacancy-exchange mechanism. This finding paves a significant avenue for cathode materials operating in low-temperature solid-oxide-fuel-cell devices and for chemical sensors with wide range of operating temperature.
Authors:
; ; ; ; ; ;  [1] ;  [2] ;  [3] ; ;  [4]
  1. Department of Physics and Astronomy, University of Texas, San Antonio, Texas 78249 (United States)
  2. Department of Physics, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003 (China)
  3. North Carolina State University, Raleigh, North Carolina 27695-8204 (United States)
  4. Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China)
Publication Date:
OSTI Identifier:
22486253
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BARIUM OXIDES; CATHODES; COBALT IONS; COBALT OXIDES; DIFFUSION; EPITAXY; FUNCTIONS; GAS FLOW; GASES; HYDROGEN; LAYERS; MONOCRYSTALS; OSCILLATIONS; OXIDATION; OXYGEN; SENSORS; SOLID OXIDE FUEL CELLS; TEMPERATURE RANGE 0065-0273 K; THIN FILMS; VACANCIES