Structural phase transition of rutile-type MgH2 at high pressures
Structural phase transition of rutile-type MgH2 at high pressures
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DOI：
10.1143/jpsj.75.074603
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发表时间：
2006-07-01
影响因子：
1.7
通讯作者：
Takemura, Kenichi
中科院分区：
文献类型：
--
作者：
Moriwaki, Toru;Akahama, Yuichi;Takemura, Kenichi
在室温下检查了 MgH2 的压力诱导结构相变高达 57GPa。具有金红石型结构的α-MgH2在环境条件下转化为具有α-PbO2结构的γ-MgH2。然而，并没有发生向伽马相的完全转变，并且这两个相共存至 9GPa。高于 9GPa，MgH2 转变为斜方相（HP1 相），并在 17 GPa 左右进一步转变为另一个斜方相（HP2 相）。 HP1 相和 HP2 相的空间群分别为 Pbc2(1) 和 Pnma（铜矿型）。铜铜矿型 MgH2 在高达 57 GPa 的压力下保持稳定。因此，压力下MaH(2)的结构顺序为金红石型->α-PbO2->Pbc2(1)->铜铜矿型，镁离子的配位数从6增加到9。
The pressure-induced structural phase transition of MgH2 was examined up to 57GPa at room temperature. alpha-MgH2 with the rutile-type structure at ambient conditions transformed to gamma-MgH2 with the alpha-PbO2 structure. A complete conversion to the gamma-phase, however, did not take place and these two phases coexisted up to 9GPa. Above 9GPa, MgH2 transformed to the orthorhombic phase (HP1-phase), and further to another orthorhombic phase (HP2-phase) at around 17 GPa. Space groups of the HP1 phase and the HP2-phase were concluded to be Pbc2(1) and Pnma (cotunnite-type), respectively. Cotunnite-type MgH2 was stable at pressures up to 57 GPa. Thus the proposed structural sequence of MaH(2) under pressure is rutile-type -> alpha-PbO2 -> Pbc2(1) -> cotunnite-type, with an increase in the coordination number of magnesium ions from 6 to 9.