Possible Orientationally Ordered States of Bucky-Cubane
نویسندگان
چکیده
For temperatures above T∗ = 130K C60⋅C8H8 forms a cubic crystal consisting of two interpenetrating fcc sublattices, one of freely rotating Buckys C60 and the other of orientationally ordered cubane C8H8. The crystal structure below a discontinuous transition is found to be orthorhombic, but the nature of the ordering of the Buckys has not yet been determined. Here possible orderings of the Buckys consistent with the size and symmetry of the orthorhombic unit cell are analyzed. Most likely inversion symmetry is preserved at the transition, in which case the small number of possible orderings are described. If inversion symmetry is removed, the point group can be C2v which supports ferroelectricity or D2 which can be confirmed by proton NMR measurements.
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