Prediction of a new ground state of superhard compound B6O at ambient conditions.
Prediction of a new ground state of superhard compound B6O at ambient conditions.
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环境条件下超硬化合物 B6O 新基态的预测
DOI：
10.1038/srep31288
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发表时间：
2016-08-08
影响因子：
4.6
通讯作者：
Zhu Q
中科院分区：
文献类型：
--
作者：
Dong H;Oganov AR;Wang Q;Wang SN;Wang Z;Zhang J;Esfahani MM;Zhou XF;Wu F;Zhu Q
亚氧化硼B6O是已知的最坚硬的氧化物，它具有Rm晶体结构(α-B6O)，可以描述为α-B6O的充氧结构，或者相当于B12二十面体的立方紧密堆积，其中两个氧原子占据了所有八面体的空隙。在这里，我们展示了这种化合物在环境条件下的一个新的基态，CMCM-B6O(β-B6O)，在我们测试的所有量子力学处理中，它被证明略有但始终更稳定。与已知的α-B6O结构相比，增加压力和温度进一步稳定了它。β-B6O也具有略高的硬度，可以使用不同的实验方案来合成。我们认为β-B6O与α-B6O混合存在，它的存在解释了实验拉曼光谱中先前未解释的谱带。
Boron suboxide B6O, the hardest known oxide, has an Rm crystal structure (α-B6O) that can be described as an oxygen-stuffed structure of α-boron, or, equivalently, as a cubic close packing of B12 icosahedra with two oxygen atoms occupying all octahedral voids in it. Here we show a new ground state of this compound at ambient conditions, Cmcm-B6O (β-B6O), which in all quantum-mechanical treatments that we tested comes out to be slightly but consistently more stable. Increasing pressure and temperature further stabilizes it with respect to the known α-B6O structure. β-B6O also has a slightly higher hardness and may be synthesized using different experimental protocols. We suggest that β-B6O is present in mixture with α-B6O, and its presence accounts for previously unexplained bands in the experimental Raman spectrum.