Molecular-motion-induced order-disorder transition in MEM(TCNQ)2

S. Oostra*, B. van Bodegom, S. Huizinga, G. A. Sawatzky, G. Gruner, J. P. Travers

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

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    Abstract

    In this paper we present and discuss proton NMR results on N-methyl-N-ethyl-morpholinium tetracyanoquinodimethanide [MEM(TCNQ)2]. Between 280 and 320 K the MEM molecules show an order-disorder transition due to flipping of the MEM ions over 180°, causing an anomalous increase in the conductivity. At the 335-K phase transition to the metallic state, a rotation of the MEM ions, probably about the N—O axis, sets in. The entropy change due to this rotation plus that due to the added electronic degrees of freedom is in reasonable agreement with specific-heat data.
    Original languageEnglish
    Pages (from-to)5004-5013
    Number of pages10
    JournalPhysical Review. B: Condensed Matter and Materials Physics
    Volume24
    Issue number9
    DOIs
    Publication statusPublished - 1981

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