Dong Huafeng, Oganov Artem R, Wang Qinggao, Wang Sheng-Nan, Wang Zhenhai, Zhang Jin, Esfahani M Mahdi Davari, Zhou Xiang-Feng, Wu Fugen, Zhu Qiang
School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China.
Department of Geosciences and Center for Materials by Design, Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794, USA.
Sci Rep. 2016 Aug 8;6:31288. doi: 10.1038/srep31288.
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.
氧化硼B6O是已知最硬的氧化物，具有Rm晶体结构（α-B6O），这种结构可描述为α-硼的填氧结构，或者等效地描述为B12二十面体的立方密堆积，其中有两个氧原子占据了所有八面体空隙。在此我们展示了该化合物在环境条件下的一种新基态，即Cmcm-B6O（β-B6O），在我们测试的所有量子力学处理中，它都略微但始终更稳定。相对于已知的α-B6O结构，压力和温度的升高会进一步使其稳定。β-B6O的硬度也略高，并且可以使用不同的实验方案合成。我们认为β-B6O与α-B6O混合存在，其存在解释了实验拉曼光谱中先前无法解释的谱带。
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