High-quality single crystals of LuB ₁₂ are grown using the induction zone melting method. The x-ray data are collected at temperatures 293, 135, 95, 50 K. The crystal structure of LuB ₁₂ can be refined with record low R -factor in the cubic Fm m symmetry group despite reiterated observations of the cubic symmetry distortions both in the unit-cell values and in the physical properties. A peculiar computing strategy is developed to resolve this contradiction. True symmetry of the electron-density distribution in LuB ₁₂ is proved to be much lower than cubic as a result, which correlates very accurately with anisotropy of transport properties of LuB ₁₂ .

Accurate low temperature charge transport measurements in combination with high-precision x-ray diffraction experiments have allowed detection of the symmetry lowering in the single domain Tm _0.19 Yb _0.81 B ₁₂ crystals that belong to the family of dodecaborides with metal–insulator transition. Based on the fine structure analysis we discover the formation of dynamic charge stripes within the semiconducting matrix of Tm _0.19 Yb _0.81 B ₁₂ . The charge dynamics in these conducting nano-size 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 cooperative Jahn–Teller effect in the boron sublattice is a cause of the large-amplitude rattling modes of the Tm and Yb ions responsible for the ‘modulation’ of the conduction band along one of the directions through the variation of 5 d- 2 p hybridization of electron states.

The structures of the ɛ-FeOOH, ɛ-FeOOD, and β-GaOOH phases, which belong to the InOOH structure type (the distorted TiO₂ structure type), are determined using single-crystal X-ray diffraction analysis. The measurements are performed on Xcalibur CCD and CAD-4F diffractometers. The calculations are carried out in space group P2_1nm with the JANA2000 program. The crystals are twinned and form aggregates related by the rotation around the b axis through an angle close to 62°. In the same crystals, the merohedral twinning is characterized by the rotation around the c axis through an angle of 180°. The alternation of these twin domains in the bulk of the crystal determines the corresponding disordering of the hydrogen positions.