Rattling mode and symmetry lowering resulting from the instability of the B12 molecule in LuB12

The dodecaboride LuB12 with cage-glass state and rattling modes has been studied to clarify the nature of the large amplitude vibrations of Lu ions. Discovered anisotropy of charge transport in conjunction with distortions of the conventional fcc symmetry of the crystal lattice may be attributed to coherent motion of Lu ions along a singular direction in the lattice. Arguments are presented in favor of cooperative dynamic Jahn-Teller effect in the boron sublattice to be the reason of the rattling mode, lattice distortion, and formation of the filamentary structure of the higher conducting channels-dynamic charge stripes.