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标题：Crystal structures and mechanical properties of osmium diboride at high pressure
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作者：Yi X. Wang ; Ying Y. Liu ; Zheng X. Yan 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2021
卷号：11
期号：1
页码：5754
DOI：10.1038/s41598-021-85334-y
出版社：Springer Nature
摘要：Abstract We have investigated the crystal structures and mechanical properties of osmium diboride (OsB 2 ) based on the density functional theory. The structures of OsB 2 from 0 to 400 GPa were predicted using the particle swarm optimization algorithm structure prediction technique. The orthorhombic Pmmn structure of OsB 2 ( oP 6-OsB 2 ) was found to be the most stable phase under zero pressure and it will transfer to the hexagonal P 6 3 / mmc structure ( hP 6-OsB 2 ) around 12.4 GPa. Meanwhile, we have discovered a new stable orthorhombic Immm structure ( oI 12-OsB 2 ) above 379.6 GPa. After that, a thorough and comprehensive investigation on mechanical properties of different OsB 2 phases is performed in this work. Further studies showed that the hardness of oP 6-OsB 2 and hP 6-OsB 2 at zero pressure is 15.6 and 20.1 GPa, while that for oI 12-OsB 2 under 400 GPa is 15.4 GPa, indicating that these three phases should be potentially hard materials rather than superhard materials. Finally, the pressure–temperature phase diagram of OsB 2 is constructed for the first time by using the quasi-harmonic approximation method. Our results showed that the transition pressures of oP 6-OsB 2 → hP 6-OsB 2 and hP 6-OsB 2 → oI 12-OsB 2 all decreases appreciably with the increase of temperature.
其他摘要：Abstract We have investigated the crystal structures and mechanical properties of osmium diboride (OsB 2 ) based on the density functional theory. The structures of OsB 2 from 0 to 400 GPa were predicted using the particle swarm optimization algorithm structure prediction technique. The orthorhombic Pmmn structure of OsB 2 ( oP 6-OsB 2 ) was found to be the most stable phase under zero pressure and it will transfer to the hexagonal P 6 3 / mmc structure ( hP 6-OsB 2 ) around 12.4 GPa. Meanwhile, we have discovered a new stable orthorhombic Immm structure ( oI 12-OsB 2 ) above 379.6 GPa. After that, a thorough and comprehensive investigation on mechanical properties of different OsB 2 phases is performed in this work. Further studies showed that the hardness of oP 6-OsB 2 and hP 6-OsB 2 at zero pressure is 15.6 and 20.1 GPa, while that for oI 12-OsB 2 under 400 GPa is 15.4 GPa, indicating that these three phases should be potentially hard materials rather than superhard materials. Finally, the pressure–temperature phase diagram of OsB 2 is constructed for the first time by using the quasi-harmonic approximation method. Our results showed that the transition pressures of oP 6-OsB 2 → hP 6-OsB 2 and hP 6-OsB 2 → oI 12-OsB 2 all decreases appreciably with the increase of temperature.