Compressibility and high-pressure structural behavior of Mg2Fe2O5
Compressibility and high-pressure structural behavior of Mg2Fe2O5
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Mg2Fe2O5 的压缩性和高压结构行为
DOI：
10.2138/am-2017-5837
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发表时间：
2017
影响因子：
3.1
通讯作者：
A. Woodland
中科院分区：
文献类型：
--
作者：
N. Siersch;T. B. Ballaran;L. Uenver;A. Woodland
摘要：在压力为17 GPa的金刚石砧池中，采用原位x射线单晶衍射研究了新型Mg2Fe2O5氧化物的可压缩性和结构行为。Mg2Fe2O5的体积可压缩性可以用二阶Birch-Murnaghan状态方程（BM2 EoS）来描述，其中V0 = 352.4(2) Å3, K0 = 171(4) GPa。用三个线性BM2方程描述了Mg2Fe2O5的轴向压缩性，发现其具有高度的各向异性。a和b晶格参数具有非常相似的可压缩性，a0 = 2.8917（11） Å，线性模量Ma= 572(16) GPa, b0 = 9.736(3) Å，线性模量Mb = 583(15) GPa。c轴是最可压缩的方向，线性模量较小[c0 = 12.520（15） Å， Mc= 404(28) GPa]。Mg2Fe2O5结构由共用边的八面体和多层三角棱镜组成。M1和M2八面体以及M3棱镜的M-O键的压缩行为取决于它们在边共享环境中的位置，这使得它们更硬，或者在角共享环境中，它们有更多的自由来扭曲和压缩。主要的压缩机制是多面体围绕M2-O1-M2角倾斜，并随着压力的增加而减小。Mg2Fe2O5最近被添加到具有M4O5化学计量学的相的稳定端元列表中，使其成为地球上地幔和过渡带中潜在的相关相。为了建立高压相的热力学活度-组成模型，了解每个端元的精确弹性参数是至关重要的。目前只对Mg2Fe2O5（本研究）和Fe4O5进行了测量。
Abstract The compressibility and structural behavior of the novel Mg2Fe2O5 oxide has been investigated by in situ single-crystal X-ray diffraction in a diamond-anvil cell up to a pressure of 17 GPa. The bulk compressibility of Mg2Fe2O5 can be described using a second-order Birch-Murnaghan equation of state (BM2 EoS) with V0 = 352.4(2) Å3 and K0 = 171(4) GPa. Three linear BM2 EoS were used to describe the axial compressibility of Mg2Fe2O5, which was found to be highly anisotropic. The a and b lattice parameters have very similar compressibilies, with a0 = 2.8917(11) Å and linear modulus Ma= 572(16) GPa and b0 = 9.736(3) Å and linear modulus Mb = 583(15) GPa, respectively. The c-axis is the most compressible direction as indicated by the smaller linear modulus [c0 = 12.520(15) Å and Mc= 404(28) GPa]. The Mg2Fe2O5 structure consists of edge-sharing octahedra alternating with layers of trigonal prisms. The compression behavior of the M-O bonds of the M1 and M2 octahedra and of the M3 prisms depend on their location in either an edge-sharing environment, which makes them stiffer, or a corner-sharing environment where they have more freedom to distort and compress. The main compression mechanism consists of a polyhedral tilting around the M2-O1-M2 angle, which decreases with increasing pressure. Mg2Fe2O5 has recently been added to the list of stable end-members of phases with M4O5 stoichiometry, making it a potentially relevant phase in the Earth’s upper mantle and transition zone. To develop thermodynamic activity-composition models for high-pressure phases, it is crucial to know the accurate elastic parameters of each individual end-member. Currently these have only been measured for Mg2Fe2O5 (this study) and Fe4O5.
影响因子：
1.6
作者：
Kurnosov, Alexander;Kantor, Innokenty;Zehnder, Beat H.
通讯作者：
Zehnder, Beat H.
影响因子：
3.5
作者：
Myhill, Robert;Ojwang, Dickson O.;Miyajima, Nobuyoshi
通讯作者：
Miyajima, Nobuyoshi