Formation and properties of water from quartz and hydrogen at high pressure and temperature
Formation and properties of water from quartz and hydrogen at high pressure and temperature
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DOI：
10.1016/j.epsl.2016.12.031
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发表时间：
2017-03
影响因子：
5.3
通讯作者：
Z. Futera;Xue Yong;Yuanming Pan;J. Tse;Niall J. English
中科院分区：
文献类型：
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作者：
Z. Futera;Xue Yong;Yuanming Pan;J. Tse;Niall J. English
石英是二氧化硅（SiO2）中最稳定的低压多晶型物，广泛存在于地壳和地幔中，具有较高的化学稳定性。尽管二氧化硅在环境条件下仅微溶于水，产生硅基弱酸性化合物，Shinozaki et al.（2014）最近表明，在高温高压条件下，水本身可以通过SiO2溶解在H2流体中形成。在这里，我们模拟了这个过程通过分子动力学技术的基础上的反应力场描述的Si O 2/H 2接口。在增加温度和压力后观察到H 2流体扩散到石英晶格中，随后解离的原子氢与SiO 2晶格中的氧原子相互作用，破坏晶格并导致水的形成。有趣的是，水是在二氧化硅的次表面区域演化出来的，并且它仍然局限在那里，与氢流体隔离，这与实验观察到的冰状光谱图案精确对应。由石英和H2形成的超压水可能是大陆地幔岩石圈成核神秘深源地震的触发因素。
Quartz, as the most stable low-pressure polymorph of silica (SiO 2), is widely abundant in Earth's crust and mantle, exhibiting relatively high chemical stability. Although silica is only slightly soluble in water at ambient conditions, producing silicon-based weakly acidic compounds, Shinozaki et al.(2014) have shown recently that water itself can be formed by dissolution of SiO 2 in H 2 fluid under high-temperature and pressure conditions. Here, we have simulated this process via molecular-dynamics techniques based on a reactive force-field description of the Si O 2/H 2 interface. Diffusion of the H 2 fluid into the quartz crystal lattice was observed upon increasing temperature and pressure, followed by interaction of dissociated, atomic hydrogen with oxygen atoms in the SiO 2 lattice, disrupting the lattice and leading to the formation of water. Interestingly, water is evolved in the subsurface region of the silica, and it remains confined there, isolated from the hydrogen fluid, which corresponds precisely to the ice-like spectroscopic patterns observed experimentally. The over-pressured water formed from quartz and H 2 is a possible trigger for nucleating enigmatic deep earthquakes in the continental mantle lithosphere.