Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Abstract

To realize the widespread use of thermoelectric (TE) applications, developing low-cost, eco-friendly, and high-performance TE materials with an optimal band gap is essential. We find that the lapieite grouprock-forming minerals buried deep in the earthwith the general formula MCuPnQ3 (M = Ni, Pt, and Pd; Pn = Sb and Bi; and Q = S and Se) comprise the key metrics to become “Thermoelectric Rockstars”. Our detailed chemical and phonon analyses show that the coexistence of weak covalent, partially ionic, and metavalent bonds and the stereoactive lone-pair electrons on Pn benefit the thermoelectric performance of the lapieite group. In PdCuBiSe3, for example, the elongated and soft Cu–Q and Pn–Q bonds along the c-axis synergistically suppress the lattice heat transport (κL) to 0.3 W m–1 K–1 and improve the power factor to 3 mW m–1 K–2 at 600 K, approaching the so-called “phonon-glass electron-crystal” paradigm. Likewise, the other members of the lapieite group achieve a high TE performance. The band structure and Fermi surface analyses indicate that the high band degeneracy (N v = 11) contributes to their high TE performance. Thus, the minerals of the lapieite group, having nontoxic and earth-abundant elements, such as the Ni-based ones, open up a quick path for developing new practical TE materials, awaiting further experimental validations.

Sn(IV) Polyanionic Materials as Efficient Visible-Light-Driven Water-Splitting Photocatalysts

“…As is common in other chalcogenides, ,, the s- and p-states of Q dominate the valence (VB) and conduction bands (CB) of K 2 Na 2 Sn 3 S 8 and Rb 3 NaSn 3 Se 8 . In both compounds, the CB consists of antibonding states (see Figure a) of Sn-5s hybridized with Se-p-states, while Q-p-states dominate the VB.…”

“…Therefore, robust covalently bonded polyanions interact with alkali metals via weak ionic bonds. The upshot here is that bonding schemes in K 2 Na 2 Sn 3 S 8 andto a lesser extentin Rb 3 NaSn 3 Se 8 are hierarchical: the coexistence of dissimilar chemical bonds within a crystal …”

“…The upshot here is that bonding schemes in K 2 Na 2 Sn 3 S 8 and�to a lesser extent�in Rb 3 NaSn 3 Se 8 are hierarchical: the coexistence of dissimilar chemical bonds within a crystal. 49 The bonding hierarchy, as in Zintl compounds, 50 and the presence of Sn 4+ can turn K 2 Na 2 Sn 3 S 8 and Rb 3 NaSn 3 Se 8 into promising materials for mild-band-gap applications (≤3 eV), such as water splitting. The superiority of tin chalcogenides (Sn−Q bonds) for energy applications has been established mainly because of their high carrier mobility.…”

Synergistic effect of alloying on thermoelectric properties of two-dimensional PdPQ (Q = S, Se)

“…27 Therefore, as in Zintl phases, we call the bonding scheme in PdPQ monolayers hierarchical: the coexistence of dissimilar chemical bonds within a crystal. 56 Such a bonding scheme explains, at least in part, the coordination environment of the cations in PdPQ. According to Pauling's third rule 57 in ionic bonds, the polyhedra arrange in a way to minimize the cations repulsion, so corner-sharing is preferred over edge-and facesharing in a crystal incorporating large cations.…”

Kanatzidisite: A Natural Compound with Distinctive van der Waals Heterolayered Architecture

“…The formation of minerals can also reveal synthetic conditions, such as when a lightning discharge over a dune in Nebraska created a novel quasicrystal of Mn 72.3 Si 15.6 Cr 9.7 Al 1.8 Ni 0.6 with 12-fold symmetry . Therefore, to expand our materials database, especially when looking for inspiration for designing novel quantum materials, crystal structures of naturally occurring minerals can be convenient and robust sources for novel semiconductors, − thermoelectrics, , superconductors, − quantum spin liquids, and topological materials. , Sulfosalts make up a large group of minerals that exhibit a unique combination of metallic and chalcogen elements. They are typically characterized by a complex crystal structure and often contain multiple elements such as lead, silver, copper, and antimony. − Sulfosalts are known for their diverse range of colors, from metallic gray to yellow, and for their semimetallic to opaque luster. , Notable examples include bournonite, PbCuSbS 3 , also known as “cogwheel ore”, renowned for its distinctive twinned crystal structure, which forms interlocking crystal patterns that resemble the teeth of gears; tennantite, Cu 12 As 4 S 13 , adopting a crystal structure made by an unique three-dimensional arrangement of tetrahedra; and jamesonite, Pb 4 FeSb 6 S 14 , a complex compound with an orthorhombic crystal structure.…”