Premium
Towards a Single Chemical Model for Understanding Lanthanide Hexaborides
Author(s) -
Munarriz Julen,
Robinson Paul J.,
Alexandrova Anastassia N.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202010638
Subject(s) - valency , lanthanide , chemical bond , chemical physics , superconductivity , covalent bond , chemistry , condensed matter physics , electronic structure , phase transition , crystallography , materials science , physics , ion , organic chemistry , philosophy , linguistics
Lanthanide hexaborides (LnB 6 ) have disparate and often anomalous properties, from structurally homogeneous mixed valency, to superconductivity, spectral anomalies, and unexplained phase transitions. It is unclear how such a diversity of properties may arise in the solids of identical crystal structures and seemingly very similar electronic structures. Building on our previous model for SmB 6 (mixed valent, with a peak in specific heat, and pressure induced magnetic phase transitions), we present a unifying dynamic bonding model for LnB 6 that explains simultaneously EuB 6 (possessing an anomalous peak in specific heat at low T, magnetic phase transitions, and no mixed valency), YbB 6 (mixed valent topological insulator), and rather ordinary LaB 6 . We show that Ln can engage in covalent bonding with boron, and, in some members of the LnB 6 family, also easily access alternative bonding states through the electron–phonon coupling. The accessibility, relative energetics, and bonding nature of the states involved dictate the properties.