Features of the local structure of rare-earth dodecaborides RB12 (R = Ho, Er, Tm, Yb, Lu). JETP Letters Volume 98, Issue 3, October 2013, Pages 165-169

The parameters of the local crystal structure of dodecaborides RB12 (R = Ho, Er, Tm, Yb, Lu) have been determined by extended X-ray absorption fine structure (EXAFS) spectroscopy. It has been shown that the vibrations of the rare-earth ion with respect to the boron cage are well described in the harmonic approximation. At the same time, the displacement of rare-earth ions from equilibrium positions of the crystal structure should be taken into account to determine the length of the R-B bond. The analysis of EXAFS spectra has revealed the displacement of 1-6% of rare-earth ions by about 0.2-0.3 Å in all compounds under investigation; this displacement at low temperatures results in the formation of a cage glass phase.