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Thermodynamic study of orthorhombic Tx and tetragonal T′ lanthanum cuprate, La2CuO4

Lilova, K. I. and Hord, R. and Alff, L. and Albert, B. and Navrotsky, A. (2013):
Thermodynamic study of orthorhombic Tx and tetragonal T′ lanthanum cuprate, La2CuO4.
In: Journal of Solid State Chemistry, Elsevier Science Publishing, pp. 91-94, 204, ISSN 00224596,
[Online-Edition: http://dx.doi.org/10.1016/j.jssc.2013.05.005],
[Article]

Abstract

The enthalpies of transition among the Tx, T′, and T–La2CuO4 phases are obtained from a combination of differential scanning calorimetry, high temperature oxide melt solution calorimetry, and transposed temperature drop calorimetry. The enthalpy of transformation of Tx to T is 2.32±0.07 kJ/mol and the corresponding entropy of transition is 4.38±0.13 J/(mol K). The T′ modification, with an average of 1.40 kJ/mol, is less stable in enthalpy than Tx but at 0.96 kJ/mol, more stable in enthalpy than T. Although we cannot rule out a small stability field at temperatures near the Tx–T transition at 530 K, T′ is most likely metastable at all temperatures.

Item Type: Article
Erschienen: 2013
Creators: Lilova, K. I. and Hord, R. and Alff, L. and Albert, B. and Navrotsky, A.
Title: Thermodynamic study of orthorhombic Tx and tetragonal T′ lanthanum cuprate, La2CuO4
Language: English
Abstract:

The enthalpies of transition among the Tx, T′, and T–La2CuO4 phases are obtained from a combination of differential scanning calorimetry, high temperature oxide melt solution calorimetry, and transposed temperature drop calorimetry. The enthalpy of transformation of Tx to T is 2.32±0.07 kJ/mol and the corresponding entropy of transition is 4.38±0.13 J/(mol K). The T′ modification, with an average of 1.40 kJ/mol, is less stable in enthalpy than Tx but at 0.96 kJ/mol, more stable in enthalpy than T. Although we cannot rule out a small stability field at temperatures near the Tx–T transition at 530 K, T′ is most likely metastable at all temperatures.

Journal or Publication Title: Journal of Solid State Chemistry
Volume: 204
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Lanthanum cuprate (La2CuO4), Transition enthalpies, High-temperature superconductor, Thermodynamics, High-temperature calorimetry
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: 09 Jan 2014 08:55
Official URL: http://dx.doi.org/10.1016/j.jssc.2013.05.005
Identification Number: doi:10.1016/j.jssc.2013.05.005
Funders: The calorimetric work was supported by the U.S. Department of Energy, grant DE-FG02-03ER46053. L.A., R.H., and B.A. acknowledge the financial support of the Deutsche Forschungsgemeinschaft.
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