Ammonium Impacts on Vibrations of Hydroxyl and Lattice of Phengite at High Temperature and High Pressure  

作　　者：Weihua Huang Yan Yang Zeming Qi Wendi Liu Zhongping Wang Yan Liu Qunke Xia 

机构地区：[1]School of Earth Sciences,Zhejiang University,Hangzhou 310027,China [2]National Synchrotron Radiation Laboratory,University of Science and Technology of China,Hefei 230026,China [3]Department of Physics,University of Science and Technology of China,Hefei 230026,China

出　　处：《Journal of Earth Science》2021年第5期1278-1286,共9页地球科学学刊（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(No.41972038);the Zhejiang Province Natural Science Foundation of China(No.LY18D020001)。

摘　　要：Dehydration in hydrous phases of the downgoing slab controls water release processes in subduction zones. Interplay between volatiles in hydrous minerals has complicated the previous knowledge of their dehydration. Phengite is an essential mineral carrying both hydrogen and nitrogen to the deep Earth. To further understand the link between nitrogen and dehydration process of phengite at an atomic level, we here carry out high temperature and high pressure vibrational spectroscopic investigations on hydroxyl and lattice of ammonium-bearing and ammonium-free phengites. The results show that heating to 800 oC hardly influences hydroxyl bonding strength, whereas pressure induces strengthening of hydrogen bonding until 10 GPa. Moreover, hydrogen transits between the sites with increasing temperature and pressure. The lattice modes soften with increasing temperature and stiffen under compression. Ammonium has no effect on hydroxyl bonding strength, but hinders hydrogen transition at high temperatures and high pressures. Ammonium does not influence the lattice at high pressures either, but delays softening of the lattice at high temperatures. These data unveil behavior of hydroxyl and lattice in phengite at high temperature and high pressure, and also evaluate ammonium impacts, shedding new lights on dehydration processes of phengite during subduction.

关 键 词：HYDROXYL LATTICE AMMONIUM PHENGITE high temperature high pressure 

分 类 号：P57[天文地球—矿物学]