Development of a Geometric Descriptor for the Strategic Synthesis of Remeika Phases

Abstract

Remeika phases, also described as pseudoperovskites, are cage-like structures with emergent properties. In this Perspective, we first cover heuristic methods used to overcome the challenges to rationalize the stability of extended solids. We highlight the important role Goldschmidt's tolerance factor has played in enhancing research related to perovskites and their derivatives. We discuss the development of a tolerance factor for predicting the stability of intermetallic pseudoperovskites, the Remeika phases, and rationalize oxidation states in correlation with valence fluctuation. To evaluate the feasibility of the Remeika phase tolerance factor, we synthesized the new predicted compound Yb 5 Ru 6 Sn 18 with a magnetic moment (μ eff ) of 3.2 μ B /Yb. We then highlight the importance of determining the factors dictating the stability of the Remeika intermetallics.

Cage compound Sc5Pt24B12: a Pt-stuffed variant of filled skutterudite structure. Electronic and structural properties

“…ScPt, ScPt 3 , Sc 2 Pt). 67 In terms of atom coordination and their spatial disposition, the structure of Sc 5 Pt 24 B 12 is related to Yb 3 Rh 4 Sn 13 (the family of so-called Remeika phases [19][20][21][22][23][24] ). In both structures, the networks of condensed trigonal prisms (edges and vertices linked [BPt 6 ] network in Sc 5 Pt 24 B 12 and network of [RhSn 6 ] linked solely via common vertices in Yb 3 Rh 4 Sn 13 ) leave two large cages, which are occupied both by Sc in the boride structure (2a and 8c crystallographic positions) (Fig.…”

“…The 2a and 8c sites are occupied by the most electropositive atoms (Sc1 and Sc2, respectively). The hitherto reported studies for RE 5−x M 12 Sn 24+x demonstrated a rich flexibility of these structures (alike filled skutterudites 8,12,52-57 and Remeika phases [19][20][21][22][23][24] with respect to population of the icosahedral site. To verify the correct atom assignment in the 2a site in Sc 5 Pt 24 B 12 , we have considered possible occupancy of this crystallographic position by (i) Sc/Pt statistical mixture and by (ii) solely Sc.…”

“…high charge carrier mobility in combination with glass-like thermal conductivity, suitable for thermoelectric applications, [12][13][14] superconductivity, [15][16][17][18] etc. The structure of Yb 3 Rh 4 Sn 13 and its derivatives (so-called Remeika phases) [19][20][21][22][23][24] also exhibit structural features that resemble the filled skutterudite structure.…”

Tolerance Factor and Phase Stability of the KCoO2-Type AMN2 Nitrides

“…21,25−27 The tolerance factor is a useful structural descriptor to rapidly evaluate the phase stability of certain materials from initial chemical species. Since Goldschmidt established the tolerance factor as a guide in the discovery and research of perovskite compounds, 28 it has been extensively extended to evaluate the structural stabilities of pyrochlores, 29 normal spinels, 30 garnet structure, 31 Remeika phases, 32 and ilmenite structure. 33 In this study, referring to perovskites, a tolerance factor t is proposed to describe the size effect on the phase/ symmetry options of the AMN 2 nitrides, in order to help understand the structural variation of the experimentally accessible compounds with the sizes of alkaline earth cations and predict the stability of other compositions.…”

Navigating the 18-n+m Isomers of PdSn2: Chemical Pressure Relief through Isolobal Bonds and Main Group Clustering

“…The Hume-Rothery factorselectronics, − atomic packing, − and electronegativity − shape our understanding of how a metallic material is stabilized. While most attention is given to systems in which one of these factors dominates, Hume-Rothery himself highlights the potential for these factors to interact in the stability ranges of some materials .…”