X-Ray Study of Compressibilities of β-(BEDT-TTF)2I3under Hydrostatic Pressure

Values of the lattice constants of the organic conductor β-(BEDT-TTF) 2 I 3 up to 2 GPa at room temperature are obtained by Buerger precession method and the compressibilities d x / x d p [/GPa] are determined as -0.044, -0.032 and -0.026, where x = a , b and c , respectively. The anisotropy factor of the compressibilities is less than 2, in contrast with the quasi-one-dimensional case of (TMTSF) 2 PF 6 . The difference is caused by the two-dimensional character of the electronic structure originated from the corrugated network of BEDT-TTF molecules.