A first principles study of boron rich compounds with high mechanical properties in high temperature

我们研究了含B_二十面体团簇的富硼化合物AlMB_（M=Li，Na，Mg）的成键性质和金属（M）对原子、电子和弹性性质<14><12>的影响。这些材料是高温下具有高机械性能的候选材料。我们发现在所有情况下，最近邻硼原子之间都有很强的成键作用。来自M原子的电荷转移使得桥接B12二十面体的硼原子表现得像碳。这些硼原子在相邻的二十面体之间形成六边形环，类似于在金刚石结构中发现的一个，在一个方向上导致不对称键合。还讨论了Si的添加效果。

We study first principles calculations on the bonding nature and metal (M) dependent changes in the atomic, electronic, and elastic properties of boron rich compounds such as AlMB_<14> (M=Li, Na and Mg) having B_<12> icosahedral clusters. These materials are candidates high mechanical properties in high temperatures. We found in all cases there is a strong bonding between the nearest neighbor boron atoms. A charge transfer from M atoms makes the boron atoms bridging the B12 icosahedra behave like carbon. These boron atoms form hexagonal rings between the neighboring icosahedra similar to the one found in the diamond structure in one direction leading to asymmetric bonding. Effects of addition of Si are also discussed.