Revealing Tendencies in the Electronic Structures of Polar Intermetallic Compounds

Abstract

Abstract:The quest for solid-state materials with tailored chemical and physical features stimulates the search for general prescriptions to recognize and forecast their electronic structures providing valuable information about the experimentally determined bulk properties at the atomic scale. Although the concepts first introduced by Zintl and Hume-Rothery help to understand and forecast the bonding motifs in several intermetallic compounds, there is an emerging group of compounds dubbed as polar intermetallic phases whose electronic structures cannot be categorized by the aforementioned conceptions. These polar intermetallic compounds can be divided into two categories based on the building units in their crystal structures and the expected charge distributions between their components. On the one hand, there are polar intermetallic compounds composed of polycationic clusters surrounded by anionic ligands, while, on the other hand, the crystal structures of other polar intermetallic compounds comprise polyanionic units combined with monoatomic cations. In this review, we present the quantum chemical techniques to gain access to the electronic structures of polar intermetallic compounds, evaluate certain trends from a survey of the electronic structures of diverse polar intermetallic compounds, and show options based on quantum chemical approaches to predict the properties of such materials.

The Crystal Orbital Hamilton Population (COHP) Method as a Tool to Visualize and Analyze Chemical Bonding in Intermetallic Compounds

“…Average-ICOHP/bond values (eV/bond) and percentage contributions to the net bonding capabilities of the homoatomic Au−Au and post-transition-metal−post-transition-metal as well as heteroatomic Au−post-transition-metal interactions for diverse active-metal-poor polar intermetallics consisting of an active-metal (main-groups I, II, and scandium-group elements), gold and a post-transition-metal. The valence-electron concentrations (e/a) are given in the second column, while details regarding the quantum-chemical calculations and the crystal structures of the respective compounds may be extracted from the references listed in the last column [45]. The crystal structures of the polar intermetallic compounds belonging to the first of the three categories are composed of cages which are assembled by the gold and post-transition-metal atoms and condensed along a particular crystallographic direction to yield one-dimensional tunnels.…”

“…Details regarding the crystal structures and their determinations may by extracted from the literature cited in the main text and in the Table 2. Parts of the figure are adapted from reference [45]. Representations of the crystal structures of (a) 35.9 , the diverse cluster shells typically observed for Bergman-type quasicrystals are shown, while atoms which are located in the unit cell but do not assemble the cluster shells have been omitted for the benefit of a clear representation.…”

“…Details regarding the crystal structures and their determinations may by extracted from the literature cited in the main text and in the Table 2. Parts of the figure are adapted from reference [45].…”

Revisiting the Zintl‒Klemm Concept for ALn2Ag3Te5-Type Alkaline-Metal (A) Lanthanide (Ln) Silver Tellurides

“…However, elucidating the nature of bonding is decisive for designing solid-state materials and their properties. Namely, the bond energy evidently contributes to the total electronic (ground state) energy, providing conclusive hints to the structural preferences of materials [3,4], while the bonding characteristics of the states near the Fermi level of a given material influence its physical properties. For instance, the latter circumstance becomes fully apparent regarding the Fermi level characteristics of certain chalcogenide superconductors [5,6], the magnetic ground state of transition-metals [7], and the optical as well as the electric properties of phase-change materials [8,9], to name but a few.…”

Revealing the Nature of Chemical Bonding in an ALn2Ag3Te5-Type Alkaline-Metal (A) Lanthanide (Ln) Silver Telluride

“…The understanding and, furthermore, the tailored design of the physical properties for a given solid-state material requires a proper knowing of its electronic (band) structure [1,2]. In addition, the knowledge of the total (electronic) energy, which is evaluated from the electronic (band) structure computations for a given material, also provides valuable information about the structural preferences and, hence, stability trends for such a substance [3,4].…”