Zintl chemistry: Current status and future perspectives

Realizing Enhanced Thermoelectric Performance in Zintl-Phase SrCuSb by Reducing the Thermal Conductivity

“…Thermoelectric materials play a very important role in applications such as waste heat energy conversion, , solid-state cooling, and power supplies . The conversion efficiency is mainly determined by the figure of merit zT ( zT = ( S 2 σ/κ) T , where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature). − Zintl-phase compounds have been considered as promising thermoelectric materials due to their “phonon-glass electron-crystal” structure. − The anion groups connected by covalent bonds in the crystal structure mainly play the role of carrier transport, while the cations that form ionic bonds with the anion groups mainly play the role of scattering phonons. Up to now, a series of Zintl compounds have been reported as promising thermoelectric materials, such as Yb 14 MnSb 11 , − YbCd 2 Sb 2 , , Eu 2 ZnSb 2 , , CaZn 0.4 Ag 0.2 Sb, Ca 10 GdCdSb 9 , Ca 9 Zn 4+ x Sb 9 , KGaSb 4 , BaAg 2 Te 2 , etc .…”

Ba6Ge2Se12 and Ba7Ge2Se17: Two Centrosymmetric Barium Seleno-Germanates with Polyatomic Anion Disorder

“…Zintl compounds are characterized by their adherence to the simple octet counting rules. The compositions of these materials are largely explained by the ionic interactions between group one and two elements with their post-transition metal counterparts. , Herein, the ternary Ba–Ge–Se phase space is investigated and expanded to include two previously unreported compounds: Ba 6 Ge 2 Se 12 and Ba 7 Ge 2 Se 17 . So far, only two barium seleno-germanates have been reported, namely, Ba 2 GeSe 4 and Ba 2 Ge 2 Se 5 . , The former is a member of a diverse class of compounds with the general formula M II 2 TtQ 4 , where M II is either one or two different divalent cations, the tetrel Tt is a tetrahedrally coordinated cation such as Si, Ge, or Sn, and Q is a chalcogen atom such as S or Se.…”

“…The compositions of these materials are largely explained by the ionic interactions between group one and two elements with their post-transition metal counterparts. 1,2 Herein, the ternary Ba−Ge−Se phase space is investigated and expanded to include two previously unreported compounds: Ba 6 Ge 2 Se 12 and Ba 7 Ge 2 Se 17 . So far, only two barium seleno-germanates have been reported, namely, Ba 2 GeSe 4 and Ba 2 Ge 2 Se 5 .…”

Observation of Anomalously High Seebeck Coefficients in the Family of Zintl Phase Semiconductors Ca10RECdSb9 (RE = Rare-Earth Metal)

“…The Zintl phases (which fall at the border of the typical valence-precise compounds and the intermetallic compounds) , have continued to provide us with numerous research opportunities to tune the electronic, optoelectronic, and transport properties that may be beneficial for thermoelectric, infrared nonlinear optics, and photovoltaic applications. − The material landscapes are rich, and discoveries of unexpected chemistry and physics abound . For thermoelectric applications, in particular, materials with narrow band gaps are sought after since they provide high carrier mobility and electrical conductivity, which are desired for developing efficient thermoelectrics. , Also, the amenability of Zintl materials to complex atomic bonding and heavy atomic site disorder that can provide for effective anharmonic phonon scatterings are also crucial features that can be harnessed toward achieving ultralow thermal conductivity .…”

“…3−5 The material landscapes are rich, and discoveries of unexpected chemistry and physics abound. 6 For thermoelectric applications, in particular, materials with narrow band gaps are sought after since they provide high carrier mobility and electrical conductivity, which are desired for developing efficient thermoelectrics. 7,8 Also, the amenability of Zintl materials to complex atomic bonding and heavy atomic site disorder that can provide for effective anharmonic phonon scatterings are also crucial features that can be harnessed toward achieving ultralow thermal conductivity.…”