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High borides: determining the features and details of lattice dynamics from neutron spectroscopya National Research Nuclear University ‘MEPhI’, Kashirskoe shosse 31, Moscow, 115409, Russian Federation b National Research Centre ‘Kurchatov Institute’, pl. akad. Kurchatova 1, Moscow, 123182, Russian Federation This paper reviews wide-ranging research that combined inelastic neutron scattering spectroscopy with phenomenological and \textit{ab initio} calculations to study the lattice dynamics and specifics of the electron--phonon interaction in three-dimensional boron cluster-network systems MB6 и MB12 (M = La, Sm, Yb, Lu, Zr). Close similarity is found between the atomic vibration spectra of these systems, which is fundamentally due to these systems' strong hierarchy of interatomic interaction and which manifests itself both in the shape of the low-energy phonon dispersion and in the position of the high-energy edge of the spectrum. Manifestations of the strong electron--phonon interactions in the lattice vibration spectra of the borides are studied in detail and their relation to the nature and features of the valence-unstable state of rare-earth ions is examined. Resonance nonadiabaticity and magnetovibration interaction effects in spin- and valence-fluctuating systems are given special attention.
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