Li Jingpeng, Zhou Yiming, Hao Shiqiang, Zhang Tianyan, Wolverton Chris, Zhao Jing, Zhao Li-Dong
The Beijing Municipal Key Laboratory of New Energy Materials and Technologies, School of Materials Sciences and Engineering , University of Science and Technology Beijing , Beijing 100083 , China.
School of Materials Science and Engineering , Beihang University , Beijing 100191 , China.
Inorg Chem. 2019 Jan 22;58(2):1339-1348. doi: 10.1021/acs.inorgchem.8b02899. Epub 2018 Dec 31.
Although the binary sulfides BiS, PbS, and SnS have attracted extensive interest as thermoelectric materials, no quaternary sulfides containing Sn/Pb/Bi/S elements have been reported. Herein, we report the synthesis of a new quaternary sulfide, SnPbBiS, which crystallizes in the orthorhombic space group Pnma with unit cell parameters of a = 20.5458(12) Å, b = 4.0925(4) Å, c = 13.3219(10) Å. SnPbBiS has a lillianite-type crystal structure consisting of two alternately aligned NaCl-type structural motifs separated by a mirror plane of PbS monocapped trigonal prisms. In the lillianite homologous series, SnPbBiS can be classified as L, where the superscripted numbers indicate the maximum numbers of edge-sharing octahedra in the two adjacent NaCl-shaped slabs along the diagonal direction. The obtained SnPbBiS phase exhibited good thermal stability up to 1000 K and n-type degenerate semiconducting behavior, with a power factor of 3.7 μW cm K at 773 K. Notably, this compound exhibited a very low lattice thermal conductivity of 0.69-0.92 W m K at 300-1000 K. Theoretical calculations revealed that the low thermal conductivity is caused by the complex crystal structure and the related elastic properties of a low Debye temperature, low phonon velocity, and large Grüneisen parameters. A reasonable figure of merit (ZT) of ∼0.3 was obtained at 770 K.
尽管二元硫化物BiS、PbS和SnS作为热电材料已引起广泛关注，但尚未见含Sn/Pb/Bi/S元素的四元硫化物的报道。在此，我们报道了一种新型四元硫化物SnPbBiS的合成，它结晶于正交空间群Pnma，晶胞参数为a = 20.5458(12) Å，b = 4.0925(4) Å，c = 13.3219(10) Å。SnPbBiS具有一种硫铋铅矿型晶体结构，由两个交替排列的NaCl型结构基序组成，中间由一个PbS单帽三角棱柱的镜面隔开。在硫铋铅矿同系物系列中，SnPbBiS可归类为L，其中上标数字表示沿对角线方向两个相邻NaCl形板中边共享八面体的最大数量。所获得的SnPbBiS相在高达1000 K时表现出良好的热稳定性和n型简并半导体行为，在773 K时功率因子为3.7 μW cm K。值得注意的是，该化合物在300 - 1000 K时晶格热导率非常低，为0.69 - 0.92 W m K。理论计算表明，低热导率是由复杂的晶体结构以及低德拜温度、低声子速度和大格林爱森参数的相关弹性性质引起的。在770 K时获得了约0.3的合理优值(ZT)。
