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Electrical Transport and Oxygen Exchange in the Superoxides of Potassium, Rubidium, and Cesium
Author(s) -
Gerbig Oliver,
Merkle Rotraut,
Maier Joachim
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201404197
Subject(s) - rubidium , caesium , ionic bonding , materials science , conductivity , oxygen , diffusion , ionic conductivity , superoxide , phase (matter) , potassium , alkali metal , electrical resistivity and conductivity , inorganic chemistry , fast ion conductor , analytical chemistry (journal) , chemical physics , ion , chemistry , electrode , thermodynamics , organic chemistry , physics , electrolyte , metallurgy , enzyme , electrical engineering , engineering
Conductivity, ionic transference number, and chemical diffusion coefficients are determined for KO 2 , RbO 2 , and CsO 2 . Based on such results, a defect‐chemical model is constructed. These superoxides are found to exhibit a total conductivity in the range of 3 × 10 –7 to 5 × 10 –5 S cm – 1 at 200 °C with contributions from ionic and electronic carriers. The ionic conductivity is caused by alkali interstitials and superoxide vacancies as mobile defects, and is found to exceed the n‐type electronic conductivity. 18 O isotope exchange on powder samples (monitoring the gas phase composition) shows that essentially all oxygen can be exchanged. At high p O 2 this largely occurs without breaking of the O–O bond—indicating a sufficient mobility of molecular superoxide species in the solid—and with an effective rate constant that is much higher than for other large‐bandgap mixed conducting materials such as SrTiO 3 .