在最初的晶体结构和相对相位稳定性中,alexite系列的PbnBi4Te4Sn+2
Jie Yao1, Cristiana L Ciobanu1, Nigel J Cook1
1School of Chemical Engineering, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.
概括
密度函数理论揭示了Pb-Bi-Te-S亚历克石系列中的晶体结构和稳定性. 硫化物含量增加与层间距离和调制结构的减少有关,使新阶段的预测成为可能.
科学领域:
- 固态化学和材料科学 固态化学和材料科学
- 结晶学和结构分析.
- 计算材料科学 计算材料科学
背景情况:
- 亚历克西特同类系列 (PbnBi4Te4Sn+2) 包含复杂的混合层化合物.
- 了解它们的晶体结构和稳定性对于材料设计至关重要.
- 之前的研究已经确定了这个系列的各种成员具有不同的结构动机.
研究的目的:
- 使用计算方法研究aleksite同源系列中的七个相的晶体结构和稳定性.
- 分析组成 (PbS含量) 和结构参数之间的关系.
- 探索调制现象,并预测系列中的潜在新阶段.
主要方法:
- 密度函数理论 (DFT) 的应用用于建模晶体结构和计算相位稳定性.
- 原子位置的放松以确定平衡结构参数 (a,c,层间距离d).
- 对电子衍射模式和调制向量 (qF,q) 的分析,以描述结构复杂性.
主要成果:
- 计算的结构参数 (a和c值) 与实验数据 (在1.5%以内) 显示出极好的一致性.
- 层间距离 (dsub) 和格子参数"a"随着PbS含量增加而减少.
- 观察到可变的 Pb-S 键长度,与 galena 中的恒定长度形成对比;在调制向量 γ 和 dsub 之间建立了线性关系.
结论:
- 亚历克西特系列展示了具有调制结构的n折叠超结构,受增积同质原则的支配.
- 建立了g和d之间的线性关系,可以预测理论阶段.
- 预测PbS丰富的上限为n = 398,dsub值与三角形PbS相比.
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