Oxygen nonstoichiometry, thermal expansion and high-temperature electrical properties of layered NdBaCo2O5+delta and SmBaCo2O5+delta
authors Aksenova, TV; Gavrilova, LY; Yaremchenko, AA; Cherepanov, VA; Kharton, VV
nationality International
journal MATERIALS RESEARCH BULLETIN
author keywords X-ray diffraction; Thermogravimetric analysis; Thermal expansion
keywords OXIDE FUEL-CELLS; CHEMISTRY; LN; CONDUCTIVITY; PEROVSKITES; CATHODES; CRYSTAL; PR; LA; SM
abstract Layered LnBaCo(2)O(5+delta) (La = Nd, Sm) with the cation-ordered double perovskite structure were synthesized by the solid-state reaction route and characterized by X-ray diffraction, thermogravimetric analysis and dilatometry. For NdBaCo2O5.73 and SmBaCo2O5.61 equilibrated with atmospheric oxygen at low temperatures, tetragonal and orthorhombic polymorphs were found to form, respectively. The oxygen content at 300-1300 K decreases with decreasing rare-earth cation size, whilst 8 variations and chemical contribution to the apparent thermal expansion in air are substantially lower compared to the disordered (Ln, A)CoO3-delta (A = Ca, Sr) analogues. The average thermal expansion coefficients are 23.1 x 10(-6) K-1 for NdBaCo2O5+delta and 20.8 x 10(-6) K-1 for SmBaCo2O5+delta at 300-1370 K and atmospheric oxygen pressure. These values are comparable to those of Bi2O3-based ionic conductors, but are incompatible with common electrolytes such as stabilized zirconia or doped ceria. The oxygen partial pressure dependencies of the total conductivity and Seebeck coefficient, studied in the P(O-2) range from 10(-10) to 1 atm, confirm predominant p-type electronic conductivity. (C) 2010 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0025-5408
year published 2010
volume 45
issue 9
beginning page 1288
ending page 1292
digital object identifier (doi) 10.1016/j.materresbull.2010.05.004
web of science category Materials Science, Multidisciplinary
subject category Materials Science
unique article identifier WOS:000281104900045
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