| A Strength Softening Phase Transition Observed in Shocked （Mg0.92,Fe0.08）SiO3 Perovskite at About 83 GPa |
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| 引用本文： | 何林,龚自正,经福谦.A Strength Softening Phase Transition Observed in Shocked （Mg0.92,Fe0.08）SiO3 Perovskite at About 83 GPa[J].中国物理快报,2008,25(1):332-335. |
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| 作者姓名： | 何林 龚自正 经福谦 |
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| 作者单位： | [1]Institute of High Pressure Physics, Southwest Jiaotong University, Chengdu 610031 [2]College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066 [3]Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900 |
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| 基金项目： | Supported by the National Natural Science Foundation of China under Grant No 10299040. We thank Liu F S, Zhou X M, and Shi C C for their helpful discussion, and Xue X for his assistance in experiments. |
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| 摘 要： | We report the experimental data of Hugoniot longitudinal sound velocity VL for natural （Mg0.92,Fe0.08）SiO3 enstatite sample at about 40-140 GPa, consisting of three new data and five previously reported data but revised by our new Hugoniot equation of state parameters. Three segments, separated by two discontinuities, appear in the VL-PH （shock pressure） plot. Analyses show that the first discontinuity at about 64 GPa, with a sharp increase of VL of about 21%, is judged to be a phase transition from enstatite to Pbnm perovskite （PV）; while the second one at about 83 GPa, with a dramatic decrease of VL of about 23%, is likely caused by a subtle structural change from Pbnm PV to tetragonal PV, accompanied by material strength softening due to melting of oxygen sublattices. This strength softening evidence is obtained first from shock wave experiments, and probably has profound implications for probing into the origin of low seismic velocity anomaly in the Earth＇s lower mantle and thus constraining the geophysical and geochemical models for the Earth＇s lower mantle.
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| 关 键 词： | 钙钛矿结构 顽辉石 地球化学模型 热动态稳定性 |
| 收稿时间： | 2007-09-16 |
A Strength Softening Phase Transition Observed in Shocked (Mg0.92,Fe0.08)SiO3 Perovskite at About 83GPa |
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| HE Lin,GONG Zi-Zheng,JING Fu-Qian.A Strength Softening Phase Transition Observed in Shocked (Mg0.92,Fe0.08)SiO3 Perovskite at About 83GPa[J].Chinese Physics Letters,2008,25(1):332-335. |
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| Authors: | HE Lin GONG Zi-Zheng JING Fu-Qian |
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| Institution: | Institute of High Pressure Physics, Southwest Jiaotong University, Chengdu 610031College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900 |
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| Abstract: | We report the experimental data of Hügoniot longitudinal sound velocity VL for natural (Mg0.92,Fe0.08)SiO3 enstatite sample at about 40--140GPa, consisting of three new data and five previously reported data but revised by our new Hügoniot equation of state parameters. Three segments, separated by two discontinuities, appear in the VL--pH (shock pressure) plot. Analyses show that the first discontinuity at about 64GPa, with a sharp increase of VL of about 21%, is judged to be a phase transition from enstatite to Pbnm perovskite (PV); while the second one at about 83GPa, with a dramatic decrease of VL of about 23%, is likely caused by a subtle structural change from Pbnm PV to tetragonal PV, accompanied by material strength softening due to melting of oxygen sublattices. This strength softening evidence is obtained first from shock wave experiments, and probably has profound implications for probing into the origin of low seismic velocity anomaly in the Earth's lower mantle and thus constraining the geophysical and geochemical models for the Earth's lower mantle. |
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| Keywords: | 91 60 Ba 62 50 +p 91 35 Ed |
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