Sn_xPt₄Sn_ySb_12−y: A Skutterudite with Covalently Bonded Filler

Abstract

A new phase, Sn(x)Pt4Sb(12-y)Sn(y), has been prepared from the elements. It exhibits a wide range of homogeneity with 0.3(2) < or = x < or = 1.0(2) and 4.2(2) < or = y < or = 7.0(2). The crystal structure and the composition were established by single-crystal and powder X-ray diffraction as well as wavelength-dispersive X-ray analysis measurements and were supported by nuclear magnetic resonance experiments. The compound is the first representative of the filled-skutterudite family with the filler atoms not located at the center of the cavity but covalently bonded to the cavity's wall, as confirmed by the analysis of chemical bonding with the electron localizability indicator. The Sn and Sb atoms share the framework site with different coordinate parameters caused by the difference in atomic size; additional tin atoms are located in the cavities of the framework. The material is a diamagnet in the whole composition range. In agreement with the calculated electronic density of states, the material reveals a metallic behavior in electronic transport. The absolute values of electrical resistivity vary with the tin-to-antimony ratio.

Flux Synthesis and Crystal Structure Determination of the Colored Skutterudite Ir2Sn3Se3

“…The structure class of the skutterudites MPn 3 (M = Co, Rh, Ir; Pn = P, As, Sb) was named after the naturally occurring mineral CoAs 3 , which was first found in 1845 by Wilhelm von Haidinger in Skutterud, Norway. [1] The skutterudites like IrAs 3 and IrSb 3 [2] crystallize in the cubic space group Im3 with 8 formula units in the unit cell. The crystal structure can be considered as a heavily distorted ReO 3 structure within a 2 ϫ 2 ϫ 2 supercell where the anion positions are displaced from the edges of the unit cell towards the center.…”

A chemists view: Metal oxides with adaptive structures for thermoelectric applications

“…Therefore, the heat conductivity of solids with lowdimensional structures like cobaltites [11,[20][21][22][23][24][25][26][27][28] and oxyselenides [29][30][31][32] (Fig. 3 [39][40][41][42][43][44][45][46] (a being the filler and y the degree of filling) and intermetallic clathrates [47]. All three materials exhibit remarkable low lattice thermal conductivities down to 0.5 Wm À1 K À1 and 1.4 Wm À1 K À1 .…”

“…In summary, complex crystal structures with different types of bonding interactions lead to low thermal conductivities . This has been not only been demonstrated for filled skutterudites but also for Zintl compounds like Yb 14 MnSb 11 , zinc antimonides , and clathrates . However, the impact on the electronic transport properties must be balanced at the same time.…”

“…In addition, framework structures containing large voids filled with heavy atoms are candidates for low lattice thermal conductivities. Prominent examples are the Sb 2 4− dumbbells in Zn 4 Sb 3 , the filled skutterudites such as A y Co 4 Sb 12 (a being the filler and y the degree of filling) and intermetallic clathrates . All three materials exhibit remarkable low lattice thermal conductivities down to 0.5 Wm −1 K −1 and 1.4 Wm −1 K −1 .…”

Ba x Pd4Sn y Sb12−y : A New Palladium-Containing Skutterudite

“…In this compound the filler Sn atoms are not located at the center of the cavity but are covalently bonded to the cavity wall. 9 The effectiveness of Pd substitution on the TE properties has been studied for Pd x Co 1Àx Sb 3 10 and Ba 0.32 Pd x Co 4Àx Sb 12 . 11 To our best knowledge, there are no data on ternary palladium-containing skutterudites, where only palladium atoms occupy the octahedral (8c) position.…”