High-temperature thermoelectric studies of A11Sb10 (A=Yb, Ca)

Brown, Shawna R.; Kauzlarich, Susan M.; Gascoin, Franck; Snyder, G. Jeffrey

doi:10.1016/j.jssc.2007.02.007

Cited by 57 publications

(53 citation statements)

References 24 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous investigations of binary alkali metal-Ga (A-Ga) solid state systems have resulted in the discovery of many new Zintl compounds, in which Ga n clusters or molecules use the electrons donated from the alkali metals to satisfy their valence requirements (12). The large electronegativity differences between alkali metals and Ga always makes these A m Ga n Zintl compounds valence-precise semiconductors, i.e., they display a relatively large band gap between occupied and unoccupied states, motivating the investigation of Zintl compounds as good thermoelectric materials above ambient temperature (13). Structurally, the Ga atoms in A m Ga n systems form icosahedral (Ga 12 ) or octahedral (Ga 6 ) clusters, analogous to those found in borane chemistry (14).…”

Section: Endohedral Gallium Clusters and Superconductivitymentioning

confidence: 99%

Endohedral gallide cluster superconductors and superconductivity in ReGa ₅

Xie

Luo

Phelan

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

We present transition metal-embedded (T@Ga n ) endohedral Gaclusters as a favorable structural motif for superconductivity and develop empirical, molecule-based, electron counting rules that govern the hierarchical architectures that the clusters assume in binary phases. Among the binary T@Ga n endohedral cluster systems, Mo 8 Ga 41 , Mo 6 Ga 31 , Rh 2 Ga 9 , and Ir 2 Ga 9 are all previously known superconductors. The well-known exotic superconductor PuCoGa 5 and related phases are also members of this endohedral gallide cluster family. We show that electron-deficient compounds like Mo 8 Ga 41 prefer architectures with vertex-sharing gallium clusters, whereas electron-rich compounds, like PdGa 5 , prefer edge-sharing cluster architectures. The superconducting transition temperatures are highest for the electron-poor, corner-sharing architectures. Based on this analysis, the previously unknown endohedral cluster compound ReGa 5 is postulated to exist at an intermediate electron count and a mix of corner sharing and edge sharing cluster architectures. The empirical prediction is shown to be correct and leads to the discovery of superconductivity in ReGa 5 . The Fermi levels for endohedral gallide cluster compounds are located in deep pseudogaps in the electronic densities of states, an important factor in determining their chemical stability, while at the same time limiting their superconducting transition temperatures. Although one can analyze the superconductivity, once discovered, through materials physics-based "k-space" pictures based on Fermi surfaces, energy band dispersions, and effective interactions, often it is chemists, whose viewpoint is instead from "real space" rather than k-space, who find such superconductors in the first place (1, 2). Given the difficulty in making extrapolations between the physics of superconductivity and the chemical stability of compounds that will be superconducting, there are as many strategies for finding new superconductors as there are researchers looking for them (3-5). Most such search strategies fail, because the interactions that give rise to superconductivity can also lead to competing electronic states or can be strong enough to tear potential compounds apart (6, 7).One chemical perspective for increasing the odds of finding superconductivity is to postulate that it runs in structural families. The perovskites are a well-known example of this in metal oxides, and in intermetallic compounds, the "122" ThCr 2 Si 2 structure type is a good example (8-10). It is the discovery of these new structural families of superconductors that often leads, sometimes slowly or sometimes quickly, to advances in new superconducting materials. Here we show that a previously unappreciated chemical family, the endohedral gallium cluster phases, is a favored chemical family for superconductivity. Further, we analyze the occurrence and hierarchical structures of such phases from a molecular perspective and then use that perspective to predict the existence and structure of a previously un...

show abstract

Section: Endohedral Gallium Clusters and Superconductivitymentioning

confidence: 99%

Endohedral gallide cluster superconductors and superconductivity in ReGa ₅

Xie

Luo

Phelan

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…16- 18 The term transition metal Zintl phase is another distinction used in the literature to describe transition metal containing compounds that are isostructural to main group metalloid containing Zintl compounds 14- 16 or, in some cases, new transition metal containing structures where the Zintl formulism provides insight into the electronic structure and bonding. [22][23][24][25][26] In a Zintl phase the Zintl anions (or transition metal-Zintl ions) provide the "electron-crystal" electronic structure through the covalently bonded network of complex anions or metalloids. Fig.…”

Section: Zintl Phasesmentioning

confidence: 99%

Zintl phases for thermoelectric devices

2007

Self Cite

View full text Add to dashboard Cite

By converting waste heat into electricity and improving the efficiency of refrigeration systems, thermoelectric devices could play a significant role in solving today's energy problems. Increasing the thermoelectric efficiency (as measured by the thermoelectric material's figure-of-merit, zT) is critical to the development of this technology. Complex Zintl phases, in particular, make ideal candidates for thermoelectric materials because the necessary "electron-crystal, phonon-glass" properties can be engineered with an understanding of the Zintl chemistry. A recent example is the discovery that Yb 14 MnSb 11 , a transition metal Zintl compound, has twice the zT as the material currently in use at NASA. This perspective outlines a strategy to discover new high zT materials in Zintl phases, and presents results pointing towards the success of this approach.

show abstract

“…In the recent years, a series of compounds having a chemical formula of A 11 M 10 (Sm 11 Ge 4 In 6 -type; A = alkaline-earth metals, rare-earth metals, and M = triels, tetrels, pnictogens) [13][14][15][16][17][18] have been widely investigated given their interesting physical properties. In particular, the series of ternary indide compounds including the RE 11 Ge 8 In 2 (RE = Gd-Tm) system [19] and the RE 11 Tt 4 In 6 (RE = Y, La, Gd-Er; Tt = Si, Ge) system [20,21] has been known for its interesting magnetocaloric effect.…”

Section: Introductionmentioning

confidence: 99%