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Si2Ge: A New VII-Type Clathrate with Ultralow Thermal Conductivity and High Thermoelectric Property.

ABSTRACT: Based on global particle-swarm optimization algorithm and density functional theory methods, we predicted an alloyed Si2Ge compond with body centered tetragonal type VII clathrate (space group I4/mmm) built by a truncated octahedron fromed by six quadrangles and eight hexagons ([4668]). Si2Ge clathrate is 0.06?eV/atom lower than VII Si clathrate and thermally stable up to 1000?K. It has an indirect band gap of 0.23?eV, high p-doping Seebeck coefficient and n-doping electrical conductivity. It owns a low lattice thermal conductivity of 0.28?W/mK at 300?K because of its weak bonding and strong anharmonic interaction of longitudinal acoustic and low-lying optical phonons. The moderate electronic transport properties together with low lattice thermal conductivity results in a high optimal thermoeletric performance value of 2.54 (1.49) at 800 (1000) K in n (p)-doped Si2Ge.

SUBMITTER: Shen J

PROVIDER: S-EPMC7033159 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Si2Ge: A New VII-Type Clathrate with Ultralow Thermal Conductivity and High Thermoelectric Property.

Shen Jinni J Xie Tianzhu T Zhang Longkun L Wang Ping P Fang Zhenxing Z

Scientific reports 20200220 1

Based on global particle-swarm optimization algorithm and density functional theory methods, we predicted an alloyed Si2Ge compond with body centered tetragonal type VII clathrate (space group I4/mmm) built by a truncated octahedron fromed by six quadrangles and eight hexagons ([4668]). Si2Ge clathrate is 0.06 eV/atom lower than VII Si clathrate and thermally stable up to 1000 K. It has an indirect band gap of 0.23 eV, high p-doping Seebeck coefficient ...[more]

PMID: 32080248

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