Understanding electronic structures is decisive for the design of solid-state materials, as its knowledge is providing invaluable information regarding the chemical and physical properties. One aspect of steady interest in electronic structure theory is the influence of lone pairs on the structural arrangements in a given solid. Herein, we report on explorations of the impact of lone pairs on the structural features of members belonging to a prolific family of alkaline-earth-metal (A) transition-metal (M,M') chalcogenides (Q). The outcome indicates that the aspects controlling the structural preferences in the inspected AMM'Q 3type tellurides are rather subtle. In addition to the results of our first-principles-based investigations, we also provide a brief overview about the structural features for these tellurides including two new representatives which have been obtained from high-temperature solid-state reactions for the very first time.

Understanding the bonding nature of solids is decisive, as knowledge of the bonding situation for any given material provides valuable information about its structural preferences and physical properties. Although solid-state tellurides are at the forefront of several fields of research, the electronic structures, particularly their nature of bonding, are typically understood by applying the Zintl-Klemm concept. However, certain tellurides comprise ionic as well as strong (polar) mixed-metal bonds, in obvious contrast to the full valence-electron transfers expected by Zintl-Klemm's reasoning. How are the valence-electrons really distributed in tellurides containing ionic as well as mixed-metal bonds? To answer this question, we carried out bonding and Mulliken as well as Löwdin population analyses for the series of ALn 2 Ag 3 Te 5 -type tellurides (A = alkaline-metal; Ln = lanthanide). In addition to the bonding analyses, we provide a brief description of the crystal structure of this particular type of telluride, using the examples of RbLn 2 Ag 3 Te 5 (Ln = Ho, Er) and CsLn 2 Ag 3 Te 5 (Ln = La, Ce), which have been determined for the first time.

Tellurides have attracted an enormous interest in the quest for materials addressing future challenges, because many of them are at the cutting edge of basic research and technologies due to their remarkable chemical and physical properties. The key to the tailored design of tellurides and their properties is a thorough understanding of their electronic structures including the bonding nature. While a unique type of bonding has been recently identified for post-transition-metal tellurides, the electronic structures of tellurides containing early and late-transition-metals have been typically understood by applying the Zintl−Klemm concept; yet, does the aforementioned formalism actually help us in understanding the electronic structures and bonding nature in such tellurides? To answer this question, we prototypically examined the electronic structure for an alkaline metal lanthanide zinc telluride, i.e., RbDyZnTe3, by means of first-principles-based techniques. In this context, the crystal structures of RbLnZnTe3 (Ln = Gd, Tb, Dy), which were obtained from high-temperature solid-state syntheses, were also determined for the first time by employing X-ray diffraction techniques.

Understanding electronic structures is important in order to interpret and to design the chemical and physical properties of solid-state materials. Among those materials, tellurides have attracted an enormous interest, because several representatives of this family are at the cutting edge of basic research and technologies. Despite this relevance of tellurides with regard to the design of materials, the interpretations of their electronic structures have remained challenging to date. For instance, most recent research on tellurides, which primarily comprise post-transition elements, revealed a remarkable electronic state, while the distribution of the valence electrons in tellurides comprising group-I/II elements could be related to the structural features by applying the Zintl-Klemm-Busmann concept. In the cases of tellurides containing transition metals the applications of the aforementioned idea should be handled with care, as such tellurides typically show characteristics of polar intermetallics rather than Zintl phases. And yet, how may the electronic structure look like for a telluride that consists of a transition metal behaving like a p metal? To answer this question, we examined the electronic structure for the quaternary RbTbCdTe3 and provide a brief report on the crystal structures of the isostructural compounds RbErZnTe3 and RbTbCdTe3, whose crystal structures have been determined by means of X-ray diffraction experiments for the very first time.