High-temperature transport properties, thermal expansion and cathodic performance of Ni-substituted LaSr{sub 2}Mn{sub 2}O{sub 7-{delta}}

Journal Article · Sat Nov 15 00:00:00 EST 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.07.038· OSTI ID:21212098

Yaremchenko, A A ^[1]; Bannikov, D O ^[1]; Kovalevsky, A V ^[1]; Cherepanov, V A ^[2]

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1. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)
2. Department of Chemistry, Ural State University, Lenin av. 51, Ekaterinburg 620083 (Russian Federation)

The substitution of manganese with nickel in LaSr{sub 2}Mn{sub 2}O{sub 7-{delta}}, where the solubility limit corresponds to approximately 25% Mn sites, enhances the Ruddlesden-Popper phase stability at elevated temperatures and atmospheric oxygen pressure. The total conductivity of LaSr{sub 2}Mn{sub 2-y}Ni{sub y}O{sub 7-{delta}} (y=0-0.4) decreases with nickel additions, whilst the average thermal expansion coefficients calculated from dilatometric data in the temperature range 300-1370 K increase from (11.4-13.7)x10{sup -6} K{sup -1} at y=0 up to (12.5-14.4)x10{sup -6} K{sup -1} at y=0.4. The conductivity and Seebeck coefficient of LaSr{sub 2}Mn{sub 1.6}Ni{sub 0.4}O{sub 7-{delta}}, analyzed in the oxygen partial pressure range 10{sup -15}-0.3 atm at 600-1270 K, display that the electronic transport is n-type and occurs via a small polaron mechanism. Reductive decomposition is observed at the oxygen pressures close to Ni/NiO boundary, namely {approx}2.3x10{sup -11} atm at 1223 K. Within the phase stability domain, the electronic transport properties are essentially p(O{sub 2})-independent. The steady-state oxygen permeability of dense LaSr{sub 2}Mn{sub 1.6}Ni{sub 0.4}O{sub 7-{delta}} membranes is higher than that of (La,Sr)MnO{sub 3-{delta}}, but lower if compared to perovskite-like (Sr,Ce)MnO{sub 3-{delta}}. Porous LaSr{sub 2}Mn{sub 1.6}Ni{sub 0.4}O{sub 7-{delta}} cathodes in contact with apatite-type La{sub 10}Si{sub 5}AlO{sub 26.5} solid electrolyte exhibit, however, a relatively poor electrochemical performance, partly associated with strong cation interdiffusion between the materials. - Graphical abstract: The substitution of manganese with nickel in Ruddlesden-Popper-type LaSr{sub 2}Mn{sub 2}O{sub 7-{delta}}, where the solubility limit corresponds to approximately 25% Mn sites, increases phase stability at elevated temperatures and thermal expansion, and decreases unit cell volume and total conductivity. The Seebeck coefficient and conductivity of LaSr{sub 2}Mn{sub 1.6}Ni{sub 0.4}O{sub 7-{delta}}, analyzed in the oxygen partial pressure range 10{sup -15}-0.3 atm at 600-1270 K, display that the electronic transport is n-type and occurs via a small polaron mechanism.

• OSTI ID: 21212098
• Journal Information: Journal of Solid State Chemistry, Vol. 181, Issue 11; Other Information: DOI: 10.1016/j.jssc.2008.07.038; PII: S0022-4596(08)00406-4; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DECOMPOSITION
LANTHANUM COMPOUNDS
MANGANESE COMPOUNDS
NICKEL
NICKEL ADDITIONS
NICKEL OXIDES
OXYGEN
PARTIAL PRESSURE
PERMEABILITY
PEROVSKITE
PHASE STABILITY
POROUS MATERIALS
STRONTIUM COMPOUNDS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
THERMAL EXPANSION