  Higher accuracy low temperature charge transport measurements in combination
with precise X-ray diffraction experiment have allowed detecting the symmetry
lowering in the single domain Tm0.19Yb0.81B12 crystals of the family of
dodecaborides with metal-insulator transition. Basing on the fine structure
analysis we discover formation of dynamic charge stripes within the
semiconducting matrix of Tm0.19Yb0.81B12. The charge dynamics in these metallic
nano-size conducting channels is characterized by broad-band optical
spectroscopy that allowed estimating the frequency (~2.4 10^11 Hz) of quantum
motion of the charge carriers. It is suggested that caused by cooperative
Jahn-Teller effect in the boron sub-lattice, the large amplitude rattling modes
of the Tm and Yb ions are responsible for modulation of the conduction band
along [110] direction through the variation of 5d-2p hybridization of electron
states.
