Electrical and thermal transport properties of synthetic tetrahedrites Cu10TM2Sb4S13 (TM = Mn, Fe, Co, Ni, Zn) and the solid solution Cu12–x Mn x Sb4S13 (0 ≤ x ≤ 2) have been studied in the context of thermoelectric performance. Among these materials, the parent compound Cu12Sb4S13 exhibits the highest power factor, which is primarily derived from a high electrical conductivity. All substituted derivatives display a significant and uniform reduction in thermal conductivity. Within the TM series, the Mn-substituted sample displays the highest ZT (0.8 at 575 K). Changing the Mn concentration to Cu11MnSb4S13 produces the highest ZT, i.e., 1.13 at 575 K. The relatively high value derives from a favorable balance of low thermal conductivity and a relatively high power factor.

The new layered compound Li(3)Ni(2)BiO(6) has been prepared by a solid-state reaction. It crystallizes in the monoclinic C2/m space group; its lamellar structure is characterized by a honeycomb ordering between Ni(2+) and Bi(5+) within the slabs, while Li(+) ions occupy octahedral sites in the interslab space. Stacking defects weakly alter the XRD pattern. By substitution of half of the nickel ions, the new phases Li(3)NiM'BiO(6) (M' = Mg, Cu, Zn) isostructural with Li(3)Ni(2)BiO(6) have been synthesized under similar conditions. All these compounds demonstrate paramagnetic behavior at high temperature, and Li(3)Ni(2)BiO(6) exhibits an antiferromagnetic ordering at 5.5 K. By topotactic molten salt ionic exchange, the new delafossite compound Ag(3)Ni(2)BiO(6) has been also obtained and characterized.

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