Post-perovskite phase transition in MgSiO3
Post-perovskite phase transition in MgSiO3
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DOI：
10.1126/science.1095932
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发表时间：
2004-05-07
期刊：
影响因子：
56.9
通讯作者：
Ohishi, Y
中科院分区：
文献类型：
--
作者：
Murakami, M;Hirose, K;Ohishi, Y
在类似于地球核-地幔边界的高压和温度下，进行了原位x射线衍射测量。结果表明，镁硅钙钛矿转变为一种新的高压形式，密度增加1.0~1.2%，层叠的SiO_6-八面体片状结构大于125千兆卡和2500开尔文(接近地幔底部2700公里深度)。D“地震不连续的成因可能是这种后钙钛矿相变，新相可能具有较大的弹性各向异性，并在剪切流中形成板状晶体的择优取向，从而在D”不连续以下引起强烈的地震各向异性。
In situ x-ray diffraction measurements of MgSiO3 were performed at high pressure and temperature similar to the conditions at Earth's core-mantle boundary. Results demonstrate that MgSiO3 perovskite transforms to a new high-pressure form with stacked SiO6-octahedral sheet structure above 125 gigapascals and 2500 kelvin (2700-kilometer depth near the base of the mantle) with an increase in density of 1.0 to 1.2%. The origin of the D" seismic discontinuity may be attributed to this post-perovskite phase transition. The new phase may have large elastic anisotropy and develop preferred orientation with platy crystal shape in the shear flow that can cause strong seismic anisotropy below the D" discontinuity.