Berardan David, Li Jing, Amzallag Emilie, Mitra Sunanda, Sui Jiehe, Cai Wei, Dragoe Nita
SP2M-ICMMO, Université Paris-Sud, Orsay F-91405, France.
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Materials (Basel). 2015 Mar 12;8(3):1043-1058. doi: 10.3390/ma8031043.
In this paper, we report on the crystal structure and the electrical and thermal transport properties of the BiCuSeSO series. From the evolution of the structural parameters with the substitution rate, we can confidently conclude that a complete solid solution exists between the BiCuSeO and BiCuSO end members, without any miscibility gap. However, the decrease of the stability of the materials when increasing the sulfur fraction, with a simultaneous volatilization, makes it difficult to obtain S-rich samples in a single phase. The band gap of the materials linearly increases between 0.8 eV for BiCuSeO and 1.1 eV in BiCuSO, and the covalent character of the Cu- (Ch = chalcogen element, namely S or Se here) bond slightly decreases when increasing the sulfur fraction. The thermal conductivity of the end members is nearly the same, but a significant decrease is observed for the samples belonging to the solid solution, which can be explained by point defect scattering due to atomic mass and radii fluctuations between Se and S. When increasing the sulfur fraction, the electrical resistivity of the samples strongly increases, which could be linked to an evolution of the energy of formation of copper vacancies, which act as acceptor dopants in these materials.
在本文中，我们报道了BiCuSeSO系列的晶体结构以及电学和热输运性质。从结构参数随取代率的演变情况来看，我们可以有把握地得出结论，在BiCuSeO和BiCuSO端元之间存在完全固溶体，不存在任何混溶间隙。然而，随着硫含量的增加，材料稳定性下降并同时伴有挥发，这使得难以获得单相的富硫样品。材料的带隙在BiCuSeO的0.8 eV至BiCuSO的1.1 eV之间呈线性增加，并且当硫含量增加时，Cu -（Ch = 硫族元素，此处即S或Se）键的共价性略有下降。端元的热导率几乎相同，但对于属于固溶体的样品，热导率显著降低，这可以用由于Se和S之间原子质量和半径波动导致的点缺陷散射来解释。当硫含量增加时，样品的电阻率大幅增加，这可能与铜空位形成能的变化有关，铜空位在这些材料中充当受主掺杂剂。
