Homologous Alkali Metal Copper Rare-Earth Chalcogenides A 2 Cu 2n Ln 4 Q 7+n ( n = 1, 2, 3)
Homologous Alkali Metal Copper Rare-Earth Chalcogenides A 2 Cu 2n Ln 4 Q 7+n ( n = 1, 2, 3)
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同系碱金属铜稀土硫属化物 A 2 Cu 2n Ln 4 Q 7 n ( n = 1, 2, 3)
DOI：
10.1021/acs.chemmater.2c00223
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发表时间：
2022
影响因子：
8.6
通讯作者：
Kanatzidis, Mercouri G.
中科院分区：
文献类型：
--
作者：
Laing, Craig C.;Shen, Jiahong;Quintero, Michael A.;Weiss, Benjamin E.;Xia, Yi;Li, Zhi;He, Jiangang;Wolverton, Chris;Kanatzidis, Mercouri G.
合成了27个A_2Cu_2nLn_4 Q_（7 +n）（A = Cs，Rb; Ln = La-Nd，Sm，Gd-Yb; Q = S，Se）系列的新成员。所有的化合物都含有含碱金属隧道的三维框架。对于每个增量inn，添加一个Cu 2 Q，其通过替换正方形平面硫属化物位点作为共边四面体并入框架中。高通量DFT计算预测许多相是化学稳定的。这些预测进行了比较，在每个组成空间中形成的相的合成结果。在合成中，较重的镧系元素显示出优先开始形成然后= 3 ACu 3Ln 2 Q5，这与预测一致。发现RbCuNd 2Se 4和RbCuTb 2Se 4在真空下在高达1000 °C的温度下热稳定。光学测量显示CsCuCe 2Se 4和RbCuTb 2Se 4的带隙分别为1.55（5）和1.62（5）eV，CsCuPr 2Se 4的功函数为4.83（5）eV。此外，Somen= 3 ACu 3Ln 2 Q5化合物由于铜原子配位而表现出负声子模式，这可能在足够低的温度下扭曲成三角平面几何形状。结果表明，Cu ~（2+）的动力学不稳定性和Cu ~（2+）四面体的畸变与镧系元素的原子序数和电负性呈线性关系. A_2Cu_2nLn_4Q_7 ~+ n化合物具有作为高温热电材料和其它半导体材料的潜在应用价值。
Twenty-seven new members of the A2Cu2nLn4Q7+n(A = Cs, Rb; Ln = La–Nd, Sm, Gd–Yb; Q = S, Se) homologous series were synthesized in one of three structural types (indicated byn= 1, 2, 3). All the compounds contained 3D frameworks with alkali-metal-containing tunnels. For each increment inn, one Cu2Q was added, which was incorporated into the framework as an edge-sharing tetrahedron by replacing a square planar chalcogenide site. High-throughput DFT calculations predicted many of the phases to be thermodynamically stable. These predictions were compared with the synthesis results for the phases formed in each composition space. In the syntheses, heavier lanthanides showed a preference to start forming then= 3 ACu3Ln2Q5, which is consistent with the predictions. RbCuNd2Se4and RbCuTb2Se4were found to be thermally stable under vacuum at temperatures up to 1000 °C. Optical measurements revealed band gaps of 1.55(5) and 1.62(5) eV for CsCuCe2Se4and RbCuTb2Se4, respectively, and a work function of 4.83(5) eV for CsCuPr2Se4. Additionally, somen= 3 ACu3Ln2Q5compounds exhibit a negative phonon mode because of a copper atom coordination, which may distort to a trigonal planar geometry at sufficiently low temperatures. The dynamic instabilities and the predicted distortion in the copper tetrahedra for then= 3 ACu3Ln2Q5compounds were found to have a linear relationship with the atomic number of the lanthanides and the electronegativity of the lanthanides. The A2Cu2nLn4Q7+ncompounds can potentially find application as high-temperature thermoelectric materials and other semiconductors.