Oxygen nonstoichiometry, thermal expansion and high-temperature electrical properties of layered NdBaCo{sub 2}O{sub 5+{delta}} and SmBaCo{sub 2}O{sub 5+{delta}}

Journal Article · Wed Sep 15 00:00:00 EDT 2010 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2010.05.004· OSTI ID:22207388

Aksenova, T. V.; Gavrilova, L. Yu. ^[1]; Yaremchenko, A. A. ^[2]; Kharton, V. V. ^[2]

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1. Department of Chemistry, Ural State University, Lenin av. 51, Ekaterinburg (Russian Federation)
2. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

Layered LnBaCo{sub 2}O{sub 5+{delta}} (Ln = 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 NdBaCo{sub 2}O{sub 5.73} and SmBaCo{sub 2}O{sub 5.61} 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 {delta} variations and chemical contribution to the apparent thermal expansion in air are substantially lower compared to the disordered (Ln, A)CoO{sub 3-{delta}} (A = Ca, Sr) analogues. The average thermal expansion coefficients are 23.1 x 10{sup -6} K{sup -1} for NdBaCo{sub 2}O{sub 5+{delta}} and 20.8 x 10{sup -6} K{sup -1} for SmBaCo{sub 2}O{sub 5+{delta}} at 300-1370 K and atmospheric oxygen pressure. These values are comparable to those of Bi{sub 2}O{sub 3}-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{sub 2}) range from 10{sup -10} to 1 atm, confirm predominant p-type electronic conductivity.

• OSTI ID: 22207388
• Journal Information: Materials Research Bulletin, Vol. 45, Issue 9; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
DILATOMETRY
DOPED MATERIALS
ELECTRICAL PROPERTIES
ORTHORHOMBIC LATTICES
OXYGEN
PEROVSKITE
THERMAL EXPANSION
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION