Synthesis, Crystal and Electronic Structures, and Thermoelectric Properties of the Novel Cluster Compound Ag₃In₂Mo₁₅Se₁₉

Abstract

Polycrystalline samples and single crystals of the new compound Ag 3 In 2 Mo 15 Se 19 were synthesized by solidstate reaction in a sealed molybdenum crucible at 1300 °C. Its crystal structure (space group R3̅ c, a = 9.9755(1) Å, c = 57.2943(9) Å, and Z = 6) was determined from single-crystal X-ray diffraction data and constitutes an Ag-filled variant of the In 2 Mo 15 Se 19 structure-type containing octahedral Mo 6 and bioctahedral Mo 9 clusters in a 1:1 ratio. The increase of the cationic charge transfer due to the Ag insertion induces a modification of the Mo−Mo distances within the Mo clusters that is discussed with regard to the electronic structure. Transport properties were measured in a broad temperature range (2−1000 K) to assess the thermoelectric potential of this compound. The transport data indicate an electrical conduction dominated by electrons below 25 K and by holes above this temperature.The metallic character of the transport properties in this material is consistent with electronic band structure calculations carried out using the linear muffin-tin orbital (LMTO) method. The complex unit cell, together with the cagelike structure of this material, results in very low thermal conductivity values (0.9 W m −1 K −1 at 300 K), leading to a maximum estimated thermoelectric figure of merit (ZT) of 0.45 at 1100 K.

Structural and Electrical Properties Characterization of Sb1.52Bi0.48Te3.0 Melt-Spun Ribbons

“…Most of the recently-discovered families of thermoelectric materials reach their maximum ZT values at high temperatures, typically between 700 and 1200 K [4][5][6][7][8][9][10][11][12]. For thermoelectric applications near room temperature, solid solutions of bismuth telluride Bi 2 Te 3 with the isomorphous compounds Sb 2 Te 3 and Bi 2 Se 3 are still nowadays the best materials with ZT values around unity in both pand n-type compounds [2].…”

Electrical, Thermal, and Magnetic Characterization of Natural Tetrahedrites–Tennantites of Different Origin

“…In the latter research, several families of semiconductors have been identified in recent years, all with very low thermal conductivity whose temperaturedependence mimics that of amorphous alloys. Among others, these include Zintl phases, 1,2 Mobased cluster compounds, [3][4][5] chalcogenide-based compounds, [6][7][8] and such cage-like structures as clathrates. 9,10 Combined with semiconductor-like properties, the extremely low thermal conductivity results in high dimensionless thermoelectric figures of merit, ZT, defined as ZT = S 2 /(qj)T where T is the absolute temperature, S the Seebeck coefficient or thermopower, q the electrical resistivity, and j the total thermal conductivity, which is the sum of a lattice contribution j l and an electronic contribution j e .…”

Synthesis, crystal structure, and electrical and magnetic properties of BaMo 6 Te 6 : A novel reduced molybdenum telluride containing infinite chains of trans-face shared Mo 6 octahedra

“…The latter compounds contain clusters such as Mo 9 , Mo 12 , Mo 15 , Mo 18 , Mo 21 , Mo 24 , Mo 30 and Mo 36 . All of these clusters result from the uniaxial trans-face-condensation of octahedral Mo 6 clusters and are present, for example, in the series of compounds M n-2 Mo 3n X 3n+2 (M = Rb, Cs; X = S, Se or Te; n = 3, 4, 5, 6, 7, 8, 10 and 12) [2][3][4][5][6][7][8][9][10][11][12].…”