Department of Materials Science and Engineering, College of Materials, Xiamen University, 361005 Xiamen, China.
Phys Chem Chem Phys. 2010 Feb 21;12(7):1585-8. doi: 10.1039/b920990e. Epub 2010 Jan 8.
The atomic arrangements and chemical bonding of stable Ge(3)Sb(2)Te(6), a phase-change material, have been investigated by means of ab initio total energy calculations. The results show that an ordered stacking of Ge-Te-Ge-Te-Sb-Te-Te-Sb-Te-Ge-Te- is the most stable configuration in respect that the -Sb-Te-Te-Sb- configuration enhances the structure stability as analyzed by electron localization function (ELF) and bond energies. Ge(3)Sb(2)Te(6) shows the character of a p-type semiconductor as seen from the density of states. The chemical bonding of Ge(3)Sb(2)Te(6) is rather inhomogeneous; strong and weak covalence coexist between Te and Sb atoms, while the strength of the covalent bonding between Te and Ge atoms of various Te-Ge bonds is very close, whereas the interaction between the neighboring Te layers is a van der Waals-type weak bond. The bonding character of Ge(3)Sb(2)Te(6) is assumed to be applied to the other pseudobinary nGeTe.mSb(2)Te(3) phase-change materials.
通过从头算总能量计算，研究了稳定的相变材料 Ge(3)Sb(2)Te(6) 的原子排列和化学成键。结果表明，Ge-Te-Ge-Te-Sb-Te-Te-Sb-Te-Ge-Te-Ge-Te 的有序堆积是最稳定的结构，因为 -Sb-Te-Te-Sb- 结构增强了结构稳定性，如电子局域函数 (ELF) 和键能所示。从态密度可以看出，Ge(3)Sb(2)Te(6) 表现出 p 型半导体的性质。Ge(3)Sb(2)Te(6) 的化学成键相当不均匀；Te 和 Sb 原子之间存在强和弱共价键，而各种 Te-Ge 键之间 Te 和 Ge 原子的共价键强度非常接近，而相邻 Te 层之间的相互作用是范德华型弱键。假设 Ge(3)Sb(2)Te(6) 的键合性质适用于其他准二元 nGeTe.mSb(2)Te(3) 相变材料。
