A Phase Transformation with no Change in Space Group Symmetry: Octafluoronaphtalene

G. S. Pawley, O. W. Dietrich

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A solid-state phase transformation in octafluoronaphthalene has been discovered at 266.5K on cooling, and at 15K higher on heating. The symmetry of both phases is found to be the same, namely monoclinic with space group P21/c. The unit cell parameters change by up to 10%, but the integrity of a single crystal, which shatters on cooling, is good enough for a single-crystal structure determination. This has been done in both phases to a sufficient accuracy that a mechanism for the transformation can be proposed. Molecules which lie parallel to one another shear to a new parallel position, the shear movement being equal to one carbon-carbon bond of the naphthalene skeleton. In this process the molecules reorient, but are still related by the same symmetry operations. This transformation, although not unique, is probably the first of its kind to be discovered in molecular systems.
    Original languageEnglish
    JournalJOURNAL OF PHYSICS C-SOLID STATE PHYSICS
    Volume8
    Issue number16
    Pages (from-to)2549-2558
    ISSN0022-3719
    DOIs
    Publication statusPublished - 1975

    Cite this