Covalent-like bondings and abnormal formation of ferroelectric structures in binary ionic salts
- 20 January 2023
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science Advances
- Vol. 9 (3), eadf8706
- https://doi.org/10.1126/sciadv.adf8706
Abstract
In the Mooser-Pearson diagram, binary ionic compoundss form into nonpolar symmetrical structures with high coordination numbers, while wurtzite structures should appear in the covalent region. Their tetrahedral bonding configurations break the inversion symmetry, with polarizations almost unswitchable due to the high barriers of abrupt breaking and reformation of covalent bonds. Here, through first-principles calculations, we find some exceptional cases of highly ionic ferroelectric binary salts such as lithium halides, which may form into wurtzite structures with covalent-like sp 3 bondings, and the origin of these abnormal formations is clarified. Their high polarizations induced by symmetry breaking are switchable, with much smoother switching pathway refrained from abrupt bond breaking due to the long-range feature of Coulomb interactions. These covalent-like ionic bondings do reduce not only their ferroelectric switching barriers but also the phase transition barriers between polar and nonpolar phases, rendering high performance in applications such as nonvolatile memory and energy storage.This publication has 30 references indexed in Scilit:
- Synthesis of a New Modification of Lithium Chloride Confirming Theoretical PredictionsZeitschrift für anorganische und allgemeine Chemie, 2009
- Is There a Wurtzite-Modification of Lithium Bromide? ? Studies on the System LiBr/LiI.ChemInform, 2005
- Generalized Gradient Approximation Made SimplePhysical Review Letters, 1996
- Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis setPhysical Review B, 1996
- Projector augmented-wave methodPhysical Review B, 1994
- Theory of polarization of crystalline solidsPhysical Review B, 1993
- Special points for Brillouin-zone integrationsPhysical Review B, 1976
- Extreme-Ultraviolet Spectra of Ionic CrystalsPhysical Review B, 1970
- On the crystal chemistry of normal valence compoundsActa Crystallographica, 1959
- THE SIZES OF IONS AND THE STRUCTURE OF IONIC CRYSTALSJournal of the American Chemical Society, 1927