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Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic, and K2NiF4-type La2CuO4

Hord, Roland and Cordier, Gerhard and Hofmann, Kathrin and Buckow, Alexander and Pascua, Gwendolyne and Luetkens, Hubertus and Alff, Lambert and Albert, Barbara (2011):
Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic, and K2NiF4-type La2CuO4.
In: Zeitschrift für anorganische und allgemeine Chemie, Wiley, pp. 1114-1117, 637, (9), ISSN 00442313, [Online-Edition: http://dx.doi.org/10.1002/zaac.201100176],
[Article]

Abstract

Through low-temperature synthesis in CsOH flux, lanthanum cuprate La2CuO4 can be obtained in a metastable form, the so-called T′ modification (tetragonal, I4/mmm, no. 139, a = 400.95(2) pm, c = 1254.08(7) pm). When heated, this T′ phase transforms into a K2NiF4-type modification, whose crystal structure was now refined from X-ray powder data (tetragonal, I4/mmm, no. 139, a = 383.29(3) pm, c = 1331.3(2) pm at T = 1073 K). The well-known orthorhombic phase (s.g. Cmce, no. 64, a = 536.14(3) pm, b = 1315.53(8) pm, c = 540.20(3) pm) – usually obtained via conventional solid state synthesis – was observed to form upon cooling from the K2NiF4-type modification. High-temperature powder diffractometry allowed crystal structure refinements for all of the three phases.

Item Type: Article
Erschienen: 2011
Creators: Hord, Roland and Cordier, Gerhard and Hofmann, Kathrin and Buckow, Alexander and Pascua, Gwendolyne and Luetkens, Hubertus and Alff, Lambert and Albert, Barbara
Title: Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic, and K2NiF4-type La2CuO4
Language: English
Abstract:

Through low-temperature synthesis in CsOH flux, lanthanum cuprate La2CuO4 can be obtained in a metastable form, the so-called T′ modification (tetragonal, I4/mmm, no. 139, a = 400.95(2) pm, c = 1254.08(7) pm). When heated, this T′ phase transforms into a K2NiF4-type modification, whose crystal structure was now refined from X-ray powder data (tetragonal, I4/mmm, no. 139, a = 383.29(3) pm, c = 1331.3(2) pm at T = 1073 K). The well-known orthorhombic phase (s.g. Cmce, no. 64, a = 536.14(3) pm, b = 1315.53(8) pm, c = 540.20(3) pm) – usually obtained via conventional solid state synthesis – was observed to form upon cooling from the K2NiF4-type modification. High-temperature powder diffractometry allowed crystal structure refinements for all of the three phases.

Journal or Publication Title: Zeitschrift für anorganische und allgemeine Chemie
Volume: 637
Number: 9
Publisher: Wiley
Uncontrolled Keywords: Cuprates, Phase transitions, Crystal structure, T′ phases, K2NiF4-type
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
07 Department of Chemistry > Fachgebiet Anorganische Chemie
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
07 Department of Chemistry
Date Deposited: 30 Mar 2012 11:10
Official URL: http://dx.doi.org/10.1002/zaac.201100176
Identification Number: doi:10.1002/zaac.201100176
Funders: Deutsche Forschungsgemeinschaft (AL 536–9/1, AL 560–9/1)
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