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The site occupancies and thermoelectric properties of tin-based clathrates Cs8M4Sn42(M=Zn,Cd,Hg)and Cs8Sn44 2were studied by the first principle calculations.We had provided an efficient way to probe the relationship between the crystalline structure and power factor.Detailed analyses indicated the p states of Sn at 16i and 24k sites together with the p states of M substitute contributed significantly to the maximum power factor,yet Cs atoms nearly did not.The dangling bonds of vacancies in Cs8Sn44 2are also discussed.The power factors of p-and n-type Cs8M4Sn42and Cs8Sn44 2at optimal temperature and carrier concentration are predicted.Our results suggest that Cs8Zn4Sn42is a promising candidate at the 5.25×1019cm–3hole carrier concentration as a high temperature thermoelectric material that is competitive to the state-of-art Ge-based clathrate thermoelectric materials.
The site occupancy and thermoelectric properties of tin-based clathrates Cs8M4Sn42 (M = Zn, Cd, Hg) and Cs8Sn44 2were studied by the first principle calculations. We had provided an efficient way to probe the relationship between the crystalline structure and power factor. Detailed analyses indicated the p states of Sn at 16i and 24k sites together with the p states of M addict significantly to the maximum power factor, yet Cs atoms nearly did not. dangling bonds of vacancies in Cs8Sn44 2are also discussed. power factors of p-and n-type Cs8M4Sn42 and Cs8Sn44 2at optimal temperature and carrier concentration are predicted.Our results suggest that Cs8Zn4Sn42is a promising candidate at the 5.25 × 1019cm-3hole carrier concentration as a high temperature thermoelectric material that is competitive to the state-of-art Ge-based clathrate thermoelectric materials.