Low-Temperature Structural Phase Transitions in Thermoelectric Tetrahedrite, Cu12Sb4S13, and Tennantite, Cu12As4S13
Low-Temperature Structural Phase Transitions in Thermoelectric Tetrahedrite, Cu12Sb4S13, and Tennantite, Cu12As4S13
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DOI：
10.1021/acs.cgd.9b00385
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发表时间：
2019-05
影响因子：
3.8
通讯作者：
V. R. Hathwar;A. Nakamura;H. Kasai;K. Suekuni;Hiromi I. Tanaka;T. Takabatake;B. Iversen;E. Nishibori-E.
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文献类型：
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作者：
V. R. Hathwar;A. Nakamura;H. Kasai;K. Suekuni;Hiromi I. Tanaka;T. Takabatake;B. Iversen;E. Nishibori-E.
黝铜矿（Cu_（12）Sb_（43）S_（13））和砷黝铜矿（Cu_（12）As_（43）S_（13））在室温下以类质同象的立方结构（I_（43）m）结晶，并分别在85和124 K下表现出相变。我们已经研究了如何通过使用单晶同步辐射X射线衍射数据的相变的晶体结构的变化。Cu_（12）Sb_（43）S_（13）的低温结构属于I42m空间群，可用2a × 2a × 2c超晶胞描述。S（2）Cu（2）6八面体的畸变是导致结构转变的主要原因。相反，Cu12As4S13的结构在转变温度以下保持其立方对称性和周期性。低温结构的特征在于S（1）和As（1）原子沿着的位置无序，Cu（2）原子的无序位置的占据率发生显著变化。Cu_（12）Sb_（4S）_（13）和Cu_（12）As_（4S）_（13）的结构相变除了具有明显的低温结构外，还伴随着负热膨胀。
Tetrahedrite (Cu12Sb4S13) and tennantite (Cu12As4S13) crystallize in isomorphous cubic structures (I43m) at room temperature and exhibit phase transitions at 85 and 124 K, respectively. We have investigated how the crystal structures change through the phase transitions using single crystal synchrotron X-ray diffraction data. The low-temperature structure of Cu12Sb4S13 belongs to the I42m space group, which is described by the 2a × 2a × 2c supercell. The distortion of S(2)Cu(2)6 octahedra is found to be responsible for the structural transformation. In contrast, the structure of Cu12As4S13 preserves its cubic symmetry and periodicity below the transition temperature. The low-temperature structure is characterized by positional disorder of S(1) and As(1) atoms along with a significant change in the occupancy of disordered sites of the Cu(2) atom. Besides distinct low-temperature structures for Cu12Sb4S13 and Cu12As4S13, the structural phase transition is further accompanied by negative thermal expansion ...