从原子角度看蛇纹石固态相变
An atomic perspective on the serpentine-chlorite solid-state transformation
摘要：
绢云母矿物是变质岩的重要组成部分，也是很有前途的纳米地质材料。蛇纹石是最丰富的蛇纹石矿物，在变质过程中可转变为蛇纹石。这种有趣的相变应该会影响俯冲带底部的非稳态蠕变和缓慢滑动过程中的变形行为，但在原子尺度上还没有从结构和化学上得到理解。在这里，我们可视化的阳离子和氧原子使用国家的最先进的低剂量扫描透射电子显微镜，并发现，重组主要涉及协同迁移的四面体阳离子和氧阴离子，再加上迁移的八面体三价阳离子水镁石样夹层。此外，我们表明，不同的蛇纹石多型导致不同的规则间层的蛇纹石和蛇纹石。我们的研究结果澄清了长期存在的难题，如何固态层硅酸盐转变发生，并导致长周期有序结构。
英文摘要：
Serpentine minerals are important components of metamorphic rocks and promising geo-materials for nanotechnology. Lizardite, the most abundant serpentine mineral, can be transformed into chlorite during metamorphism. This intriguing phase transformation should affect the deformation behavior during aseismic creep and slow slip at the base of the subduction zone, but has not been understood structurally and chemically at the atomic scale. Here we visualized cations and oxygen atoms using the state-of-the-art low-dose scanning transmission electron microscopy and found that restructuring mainly involves the synergistic migration of tetrahedral cations and oxygen anions, coupled with the migration of octahedral trivalent cations into the brucite-like interlayer. Further, we show that different serpentine polytypes result in distinct regular interstratifications of serpentine and chlorite. Our results clarify the long-standing puzzle of how solid-state layer silicate transformations occur and lead to long-period ordered structures.
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