Fig. 1. (a) XRD patterns of the hot-pressed BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3, 0.4) samples; (b) cell volume V; (c) lattice parameter c; (d) lattice parameter a as a function of the Se content. The standard XRD pattern of BiCuTeO in (a) is calculated from the Rietveld refinement data given by literature^[23]. The solid lines in (b)−(d) are the linear fitting results of the experiment data. BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3和0.4) 热压样品的　(a) XRD图谱; (b)晶胞体积V; (c) 晶格常数c; (d) 晶格常数a. 图(a) 中提供的BiCuTeO标准图谱为文献精修数据计算所得^[23]; 图(b)—图(d) 中实线为线性拟合结果

Fig. 2. SEM images of polished samples (the insets are the EDS elemental mapping images) ((a)—(c)) and SEM images of fracture surfaces ((d)−(f))for BiCuTe_1–xSe_xO (x = 0, 0.2, 0.4) compounds. BiCuTe_1–xSe_xO (x = 0, 0.2和0.4) 抛光样品的SEM图像（插图为相应的EDS面扫描元素分布图像）((a)—(c))以及断面SEM形貌图((d)—(f))

Fig. 3. Temperature dependent electrical transport properties of BiCuTe_1-xSe_xO (x = 0, 0.1, 0.2, 0.3, 0.4) samples: (a) Electrical conductivity σ; (b) Seebeck coefficients S; (c) power factor S²σ. (d) Se cotent dependence of room temperature hole concentration n and mobility . The dashed and dotted lines in (a)−(c) represent the electrical transport properties of undoped BiCuSeO^[14] and BiCuTeO^[23], respectively. BiCuTe_1-xSe_xO样品 (x = 0, 0.1, 0.2, 0.3和0.4) 的　(a) 电导率σ; (b) Seebeck系数S; (c) 功率因子S²σ随温度的变化曲线; (d) 样品的载流子浓度n和迁移率 随Se含量的变化曲线. 图(a)—(c) 中短划线和点划线分别为文献中未掺杂的BiCuTeO^[23]与BiCuSeO^[14]的电输运性能

Fig. 4. Hole concentration n dependent effective mass m^* of (a) Heavily doped BiCuSeO^[14,16,28] and BiCuTeO^[24,25]; (b) Se doped BiCuTeO (this work) and Te doped BiCuSeO^[28]. (a) 重掺杂BiCuSeO^[14,16,28]和BiCuTeO^[24,25]的载流子有效质量m^*随载流子浓度n的变化曲线; (b) Se掺杂BiCuTeO(本工作)和Te掺杂BiCuSeO^[28]的载流子有效质量m^*随载流子浓度n的变化曲线

Fig. 5. Temperature dependent thermal transport properties of BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3, 0.4) samples: (a) Total thermal conductivity; (b) the combination of lattice and bipolar thermal conductivity, and the electronic thermal conductivity. The dashed and dotted lines in (a) represent the total thermal conductivities of undoped BiCuTeO^[23] and BiCuSeO^[14], respectively. BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3和0.4) 样品的(a) 总热导率和(b) 电子热导率、晶格热导率与双极扩散热导率之和随温度的变化曲线. 图(a)中短划线和点划线分别为未掺杂的BiCuTeO^[23]与BiCuSeO^[14]的热输运性能

Fig. 6. Temperature dependent zT values of BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3, 0.4) samples. The dashed and dotted lines represent the zT values of undoped BiCuTeO^[23] and BiCuSeO^[14], respectively. BiCuTe_1–xSe_xO (x = 0, 0.1, 0.2, 0.3和0.4)样品的zT值随温度的变化曲线. 短划线和点划线分别为未掺杂的BiCuTeO^[23]与BiCuSeO^[14]的zT值