Composition dependence of spin transition in (Mg,Fe)SiO3 bridgmanite
Composition dependence of spin transition in (Mg,Fe)SiO3 bridgmanite
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(Mg,Fe)SiO3 桥石中自旋跃迁的成分依赖性
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
P. Gillet
中科院分区：
文献类型：
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作者：
Susannah M Dorfman;J. Badro;P. Rueff;P. Chow;Yuming Xiao;P. Gillet
摘要（Mg，Fe）SiO_3桥镁石的自旋跃迁对地球下地幔的化学和动力学有重要意义，但在实验中表征起来比较复杂。我们研究的自旋态的铁在高度富铁bridgmanite合成顽火辉石与测量组成（Mg0.61Fe0.38Ca0.01）SiO 3和（Mg0.25Fe0.74Ca0.01）SiO 3。在78-88 GPa和1800-2400 K下合成了Bridgmanite，并在减压至1 bar（两种组合物）和压缩至126 GPa [（Mg0.61Fe0.38Ca0.01）SiO 3 only]时测量了X射线发射光谱，而没有额外的激光加热。观测到的光谱证实，铁在这些bridgmanites占主导地位的高自旋在下地幔。然而，在74%FeSiO3组合物中，总自旋矩在~50 GPa时开始减小。这些结果支持密度泛函理论预测的一个较低的自旋转变压力在高度富铁bridgmanite和潜在的解释高溶解度的FeSiO 3在bridgmanite在对应于地球的深部下地幔的压力。
Abstract Spin transitions in (Mg,Fe)SiO3 bridgmanite have important implications for the chemistry and dynamics of Earth’s lower mantle, but have been complex to characterize in experiments. We examine the spin state of Fe in highly Fe-enriched bridgmanite synthesized from enstatites with measured compositions (Mg0.61Fe0.38Ca0.01)SiO3 and (Mg0.25Fe0.74Ca0.01)SiO3. Bridgmanite was synthesized at 78-88 GPa and 1800-2400 K and X‑ray emission spectra were measured on decompression to 1 bar (both compositions) and compression to 126 GPa [(Mg0.61Fe0.38Ca0.01)SiO3 only] without additional laser heating. Observed spectra confirm that Fe in these bridgmanites is dominantly high spin in the lower mantle. However, the total spin moment begins to decrease at ~50 GPa in the 74% FeSiO3 composition. These results support density functional theory predictions of a lower spin transition pressure in highly Fe-enriched bridgmanite and potentially explain the high solubility of FeSiO3 in bridgmanite at pressures corresponding to Earth’s deep lower mantle.
下地幔钙钛矿中的中间自旋亚铁
DOI：
10.1038/ngeo309
发表时间：
2008
期刊：
影响因子：
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作者：
C. McCammon;I. Kantor;O. Narygina;J. Rouquette;U. Ponkratz;I. Sergeev;M. Mezouar;V. Prakapenka;L. Dubrovinsky
通讯作者：
L. Dubrovinsky