标题： 至160 GPa的结晶橄榄石：宇宙中最丰富的矿物之一令人惊讶的亚稳态 显示英文标题

标题： Crystalline forsterite to 160 GPa: the striking metastability of one of Universe's most abundant minerals

摘要： 在宇宙中最重要的事件之一是大型撞击，它会产生快速演化的极端压力和温度。 (Mg, Fe)₂SiO₄ 的晶体形式和无定形形式在行星中以及太空中广泛存在且丰富。 人们预计，在决定行星形成和演化的许多关键过程中，这些矿物的行为会偏离热力学平衡，尤其是冲击事件。 为了进一步了解硅酸盐在极端条件下的行为，我们用静态压力将一颗橄榄石晶体加压至最高达 160.5 GPa（远超出该化合物的稳定区域），并使用同步加速器微衍射研究了它的长程有序性。 我们发现，橄榄石在达到最高压力时仍保留长程有序性。 橄榄石 III 在约 58 GPa 处出现，并在压缩至 160.5 GPa 和在减压至约 13 GPa 的过程中持续存在，形成了罕见的约 150 GPa 的亚稳相共存现象。 这些观察结果反驳了之前关于压力诱导无定形化的报告，也是准静水压力下晶体状态韧性的一个独特证明。 我们确认，从橄榄石 III 减压可以获得高度无序的橄榄石，这与进一步减压后在 7 GPa 时观察到的长程有序性显著损失一致。 这种动力学路径可能解释了为何在冲击实验中获得了合成橄榄石玻璃，也可能是在星际尘埃中产生无定形橄榄石的一种机制。 120 GPa 的 Hugoniot 不连续性在我们的数据中没有对应点，表明静态“冷压缩”与动态压缩之间的平行关系发生了偏离。 显示英文摘要

摘要： Among Universe's most consequential events are large impacts generating rapidly-evolving extreme pressures and temperatures. Crystalline and amorphous forms of (Mg, Fe)2SiO4 are abundant and widespread, within planets and in space. The behavior of these minerals is expected to deviate form thermodynamic equilibrium in many of the processes that are critical to the formation and evolution of planets, particularly shock events. To further the understanding of the behavior of the silicate under extreme conditions, we statically compressed a crystal of forsterite up to 160.5 GPa, far beyond the compound's stability field, and probed its long-range ordering with synchrotron microdiffraction. We found that forsterite retains long-range ordering up to the highest pressure reached. Forsterite III, emerging at about 58 GPa, persists in compression to 160.5 GPa and in decompression down to about 13 GPa, for a rare combined occurrence of a metastable phase of nearly 150 GPa. These observations dispute earlier reports of pressure-induced amorphization and are a unique testimony of the resilience of the crystalline state in quasi hydrostatic compression. We confirm that highly disordered forsterite can be obtained from the decompression of forsterite III as suggested from the substantial loss of long-range ordering observed at 7 GPa after further decompression. Such kinetic pathway may explain how synthetic olivine glass have been obtained in shock experiments and could be a mechanism of generation of amorphous forsterite in cosmic dust. The 120 GPa Hugoniot discontinuity finds no correspondence in our data, marking a departure from the parallelism between static "cold compression" and dynamic compression.