Vibrational properties of boron and boron-rich compounds
Vibrational properties of boron and boron-rich compounds
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DOI：
10.1063/1.35609
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发表时间：
1986-04
期刊：
影响因子：
--
通讯作者：
H. Werheit
中科院分区：
文献类型：
--
作者：
H. Werheit
硼的变体中和高级硼化物中的原子优选以二十面体或相关结构单元排列。尽管二十面体内的键强度很强，但晶体不能被认为是分子晶体，因为二十面体间的键强度相当或甚至更强。虽然声学振动主要由各向异性但平均的晶体性质决定，但光学振动需要考虑实际晶格内的详细原子排列和键合。通过对称性分析和群论方法获得的α-菱面体硼、β-菱面体硼和碳化硼的可能的光学活性和拉曼活性声子与实验获得的光谱和理论计算进行了比较。晶格振动谱的主要部分来源于在实际晶场中几乎对称分裂的二十面体的振动，并因此受到二十面体间的振动。
The atoms in the modifications of boron and in the higher borides are preferably arranged in icosahedra or related structural units. In spite of the strong intra‐icosahedral bond strength, the crystals cannot be considered as molecular crystals, since the inter‐icosahedral bond strengths are comparable or even stronger. While the acoustic vibrations are mainly determined by the anisotropic but averaged crystal properties, the optical vibrations demand the consideration of the detailed atomic arrangement and bonding within the actual lattice. The possible optical‐active and Raman‐active phonons of alpha‐rhombohedral boron, beta‐rhombohedral boron, and boron carbide obtained by analysis of symmetry properties and group theoretical methods, are compared with the spectra obtained experimentally, and with theoretical calculations. Main portions of the lattice vibration spectra originate from vibrations of the icosahedron nearly symmetrically split in the actual crystal field, and consequently by the intericosa...