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由价值电子度驱动的相变:调整Gd5GaxGe4-x中的板间键距离
Yurij Mozharivskyj1, Wonyoung Choe, Alexandra O Pecharsky
1Ames Laboratory, Iowa State University, Ames, Iowa 500110, USA.
Journal of the American Chemical Society
|December 5, 2003
概括
Gd(5) Ga(x) Ge(4-x) 化合物的晶体结构取决于电子度. 较高的电子数量破坏了T-T二极体,改变了这个加多合金系统中的晶体结构.
科学领域:
- 固态化学 固态化学
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
背景情况:
- Gd(5) Ga(x) Ge(4-x) 系统表现出复杂的结构行为.
- 了解组成,电子度和晶体结构之间的关系对于材料设计至关重要.
研究的目的:
- 为了研究Gd(5) Ga(x) Ge(4-x) 系统的结构演变.
- 为了确定价值电子度对板间T-T二极管距离和晶体结构的影响.
主要方法:
- X射线单晶和粉末衍射研究.
- 紧密结合的线性饼-锡轨道 (TB-LMTO) 计算.
主要成果:
- 低Ga含量 (x ≤ 0.6) 和高电子度 (30.4-31 e-/formula) 的相采用了Sm(5) Ge(4) 类型结构,带有破碎的T-T二极体.
- 含有较高Ga含量 (1 ≤ x ≤ 2.2) 和较低电子度 (28.8-30 e-/formula) 的相表现出Pu(5) Rh(4) -或Gd(5) Si(4) -类型结构与完整的T-T二极体.
- 对于Gd(5) GaGe(3) 已确定了一个中间的Pu(5) Rh(4) 型结构.
- 电子结构计算表明,将Ga替换为Ge会增加在抗结合状态中的电子数量,从而导致二极体拉伸和裂变.
结论:
- 价值电子度是控制晶体结构和Gd(5) Ga(x) Ge(4-x) 系统中板间T-T二极体形成的关键因素.
- 观察到的结构转变是由电子带填充的变化驱动的,影响T-T二度体内的结合.
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