A neutron diffraction study of the extent of disorder in the low temperature (20 K) structure of β-(BEDT-TTF)2I2Br

Abstract The structure of β-(BEDT-TTF) 2 I 2 Br at 20 K has been determined from single crystal time-of-flight neutron diffraction data. The (I-I-Br) − anion remains disordered and the BEDT-TTF, or “ET”, molecules (including the terminal ethylene groups) remain ordered at low temperature. This indicates that disorder in the anion alone appears sufficient to suppress superconductivity as observed in electrical properties measurements.