POWDER OR SINGLE CRYSTAL STRUCTURE - EXEMPLIFIED BY b - (ET)2I3
D. Madsen1,2, M. Burghammer1, S. Fiedler1 and H. Müller1
1ESRF, BP220, F-38043 Grenoble Cedex,
France.
2Centre for Crystallographic
Studies, University of Copenhagen, Universitetsparken 5, DK-2100
Copenhagen, Denmark.
The organic superconductor b-(ET)2I3 is a well-known system [1]. Former studies on electrochemically produced crystals have shown that the crystals contain a mixture of phases and that the Tc is 1.4K. Furthermore, a structural phase transition is observed at 175K [2]. Using a novel preparation method, a powder has been obtained containing the pure phase of b-(ET)2I3 with a Tc of 7.1-7.9K [3]. A powder study of the phase pure crystals was performed, but the refinement showed unrevealed structural features related to the superconducting properties of the compound. At ID13 at the ESRF, we have therefore performed a single-crystal study on a crystal with dimensions 12x10x2 mm. Full data collections were carried out to a resolution of 0.6 A at both 200K and 100K. No structural phase-transition was observed in this temperature interval of the phase pure single-crystals as was previously observed in the electrochemically produced crystals [3].