Maynard-Casely H E, Lundegaard L F, Loa I, McMahon M I, Gregoryanz E, Nelmes R J, Loveday J S
SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom.
J Chem Phys. 2014 Dec 21;141(23):234313. doi: 10.1063/1.4903813.
From a combination of powder and single-crystal synchrotron x-ray diffraction data we have determined the carbon substructure of phase B of methane at a pressure of ∼8 GPa. We find this substructure to be cubic with space group I4¯3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) Å at 8.3(2) GPa, which is a factor of √2 larger than had previously been proposed by Umemoto et al. [J. Phys.: Condens. Matter 14, 10675 (2002)]. The substructure as now solved is not related to any close-packed arrangement, contrary to previous proposals. Surprisingly, the arrangement of the carbon atoms is isostructural with that of α-manganese at ambient conditions.
通过粉末和单晶同步辐射X射线衍射数据相结合，我们确定了在约8吉帕压力下甲烷B相的碳子结构。我们发现该子结构为立方晶系，空间群为I4¯3m，晶胞中有58个分子。在8.3(2)吉帕时，晶胞的晶格参数a = 11.911(1) Å，这比上本元等人[《物理学报：凝聚态物质》14, 10675 (2002)]之前提出的值大√2倍。与之前的提议相反，现在解析出的子结构与任何密堆积排列都无关。令人惊讶的是，碳原子的排列在环境条件下与α-锰的排列同构。
