|
authors |
Kravchenko, E; Neagu, A; Zakharchuk, K; Grins, J; Svensson, G; Pankov, V; Yaremchenko, AA |
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nationality |
International |
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journal |
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY |
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author keywords |
Layered compounds; Nonstoichiometric compounds; Mixed-valent compounds; Nickelates; Solid-state structures; Conducting materials |
|
keywords |
ELECTROCHEMICAL PROPERTIES; CRYSTAL-CHEMISTRY; OXIDATION-STATE; MIXED-OXIDE; SOL-GEL; LA2-XSRXNIO4; DEFECT; NONSTOICHIOMETRY; CONDUCTIVITY; TRANSPORT |
|
abstract |
High-temperature characterization of oxygen-deficient Sr-rich (La1-xSrx)(2)NiO4-delta (x = 0.5-0.8) solid solutions under mildly reducing conditions with p(O-2) approximate to 5x10(-5) atm was performed by employing structural and thermal analysis, TEM, and electrical conductivity measurements. Oxygen losses from the crystal lattice on reduction were found to result in a reversible transition from the tetragonal (I4/mmm) to the orthorhombic (Immm) structure and shrinkage of the crystal lattice for the compositions with x > 0.5. TEM and thermogravimetric analysis evidenced slow kinetics of the structural transition. The increase in oxygen deficiency under reducing conditions is accompanied by localization of the electronic charge carriers, a drop of the p-type electronic conductivity, and a transition from metallic-like to semiconducting behavior. The extent of changes in oxygen nonstoichiometry, unit--cell dimensions, average Ni oxidation state, electron-hole concentration, and electronic conductivity on reduction is interrelated with the strontium content. The results suggest that the electrical conductivity of (La1-xSrx)(2)NiO4-delta ceramics depends mainly on the average Ni oxidation state. |
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publisher |
WILEY-V C H VERLAG GMBH |
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issn |
1434-1948 |
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year published |
2018 |
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issue |
28 |
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beginning page |
3320 |
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ending page |
3329 |
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digital object identifier (doi) |
10.1002/ejic.201800091 |
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web of science category |
Chemistry, Inorganic & Nuclear |
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subject category |
Chemistry |
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unique article identifier |
WOS:000440288700005
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