Wang Baoyun, Liu Jin, Zhang Yanyao, Nie Baisheng, Yang Wei, Hao Jialong, Ding Xing, Tian Yongjun
School of Earth Sciences, Lanzhou University, Lanzhou, 730000, China.
Center for High Pressure Science, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066004, China.
Nat Commun. 2025 Jan 26;16(1):1038. doi: 10.1038/s41467-025-56312-z.
Hydrous aluminosilicates are important deep water-carriers in sediments subducting into the deep mantle. To date, it remains enigmatic how hydrous aluminosilicates withstand extremely high temperatures in the mantle transition zone. Here we systematically investigate the crystal structures and chemical compositions of typical hydrous aluminosilicates using single-crystal X-ray diffraction, electron probe microanalyzer, and nanoscale secondary ion mass spectrometry. These single crystals are synthesized at 15.5-22.0 GPa and 1400-1700 °C, featuring pervasive structural disorders. In particular, Al and Si atoms extensively occupy new tetrahedral and octahedral sites that are nominally vacant in their ordered counterparts. High temperature activates disorders leading to variable local crystal structures and more hydrogen incorporation into the crystal structure. This result suggests that the order-to-disorder transition holds the key to the high thermal stability of hydrous aluminosilicates, significantly affecting the water cycle in the deep mantle.
含水铝硅酸盐是俯冲到深部地幔的沉积物中重要的深部水载体。迄今为止，含水铝硅酸盐如何在地幔过渡带承受极高温度仍是个谜。在此，我们使用单晶X射线衍射、电子探针微分析仪和纳米级二次离子质谱系统地研究了典型含水铝硅酸盐的晶体结构和化学成分。这些单晶是在15.5 - 22.0吉帕和1400 - 1700℃下合成的，具有普遍的结构无序性。特别是，铝和硅原子广泛占据了其有序对应物中名义上为空的新四面体和八面体位点。高温激活无序性，导致局部晶体结构可变，并使更多氢掺入晶体结构。这一结果表明，有序-无序转变是含水铝硅酸盐高热稳定性的关键，对深部地幔中的水循环有显著影响。
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