Equations of state of RbxC60 (x=3,4 and 6).
Résumé
The equations of state (EOS) of RbxC60 (x = 3, 4, and 6) were determined by high pressure x-ray diffraction measurements. We focus on Rb4C60 since a Mott insulator-metal transition can be induced at around 0.8 GPa. We observed an abrupt jump in the compressibility of Rb4C60 between 0.5 GPa and 0.8 GPa which is attributed to a structural phase transition preserving the tetragonal symmetry. By ab initio calculations we are able to reproduce the experimental equations of state of RbxC60 (x = 3,4). These calculations permit us to study the pressure dependence of the internal coordinates.