Low-temperature crystallization of structural defects in LuB$_{12}$ according to $^{175}$Lu NMR data

Studies of dodecaboride LuB$_{12}$ in the temperature range of 10–300 K show that the $^{175}$Lu spectrum is broadened due to the scatter of quadrupole frequency shifts caused by the defects in the Lu sublattice. To explain the discovered hysteresis in the temperature dependence of the $^{175}$Lu linewidth, a scenario of “crystallization of structural defects” is proposed, in which the defects of the Lu sublattice, disordered at room temperature, are transformed into a more symmetrical and stable configuration with decreasing temperature, apparently due to static distortions of the boron frame caused by the cooperative Jahn–Teller effect.