Exploring the AgSb1−xBixI4 phase diagram: Thermochromism in layered CdCl2-type semiconductors
Exploring the AgSb1−xBixI4 phase diagram: Thermochromism in layered CdCl2-type semiconductors
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DOI：
10.1016/j.jssc.2021.121997
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发表时间：
2021-05
影响因子：
3.3
通讯作者：
M. Gray;Eric T. McClure;N. Holzapfel;Felipe Pacci Evaristo;W. Windl;P. Woodward
中科院分区：
文献类型：
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作者：
M. Gray;Eric T. McClure;N. Holzapfel;Felipe Pacci Evaristo;W. Windl;P. Woodward
用固相反应法合成了AgSbI 4和几种AgSb 1-xBixI 4化合物。两个端元和所有中间组分都以CdCl 2结构类型（空间群= R3 <$m）和Ag+和Sb 3+/Bi 3+阳离子的随机分布结晶。假设的阳离子有序结构已经产生，并与密度泛函理论评估其稳定性。这种分析表明，虽然电荷平衡层是非常有利的，有利于有序堆叠层的长程相互作用太弱，不能产生三维阳离子有序。这些材料的颜色在加热时会发生明显的变化，这表明存在很大的热致变色效应。例如，AgSb 0· 25 Bi 0· 75 I 4的带隙从室温下的1.68 eV变为150 ° C下的1.55 eV。这种带隙的热致变色位移大于类似金刚石的半导体，如CdTe。VASP计算和分子动力学模拟表明，大的热致变色效应主要是由显着的电子-声子耦合。
AgSbI 4 and several AgSb 1–x Bi x I 4 compositions have been synthesized via solid state reactions. Both end members and all intermediate compositions crystallize with the CdCl 2 structure type (space group= R 3¯ m) and a random distribution of the Ag+ and Sb 3+/Bi 3+ cations. Hypothetical cation ordered structures have been generated and their stabilities evaluated with density functional theory. This analysis suggests that while charge balanced layers are strongly favored, the long-range interactions that favor ordered stacking of layers are too weak to produce three-dimensional cation ordering. The colors of these materials change noticeably when heated, signaling a large thermochromic effect. For example, the band gap of AgSb 0· 25 Bi 0· 75 I 4 changes from 1.68 eV at room temperature to 1.55 eV at 150° C. This thermochromic shift in band gap is larger than comparable diamond-like semiconductors, such as CdTe. VASP calculations and molecular dynamics simulations indicate the large thermochromic effect is primarily caused by significant electron-phonon coupling.