A first-principles study of helium diffusion in aragonite under high pressure up to 40 GPa  

作　　者：Yu Huang Mingqiang Hou Hong Liu 

机构地区：[1]United Laboratory of High-Pressure Physics and Earthquake Science,Institute of Earthquake Forecasting,China Earthquake Administration(CEA),Beijing 100036,China [2]State Key Laboratory of Geodesy and Earth's Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 433077,China

出　　处：《Geoscience Frontiers》2025年第1期363-371,共9页地学前缘(英文版)

基　　金：supported by National Natural Science Foundation of China(Grant Nos.42394114,41573121,42174115);Open Foundation of the United Laboratory of High-Pressure Physics and Earthquake Science(Grant No.2019HPPES06).

摘　　要：Helium diffusion in carbonates under mantle pressure is crucial for understanding thermal and chemical evolution of mantle.Based on the density functional theory(DFT)and the the climbing image nudged elastic band(CI-NEB)method,we performed first-principles calculations of diffusion characteristics of helium in perfect aragonite crystal under high pressure to 40 GPa.Our results show that He diffusion behaviors are controlled by pressure,temperature and crystal size.The activation energy increases,and the diffusion coefficients decrease significantly under high pressure.Ea[100]increases from 176.02 kJ/mol to 278.75 kJ/mol,and Ea[001]increases from 195.89 kJ/mol to 290.43 kJ/mol,with pressure increasing from 20 GPa to 40 GPa.At 700 K,the diffusion coefficients at 40 GPa is 7 orders of magnitude lower than that at 20 GPa;and at 1000 K it decrease 5 orders of magnitude.To ensure that at least 90%helium is not lost,we synthesized the temperature obtained from cooling and heating processes and derive the'stable temperature range'for helium in aragonite.The obtained results show that the stable temperature range is 22-76℃at 0 GPa and 641-872℃at 40 GPa,for the crystal of 100-2000μm size.Besides,the travel time of helium in aragonite under high pressure increases rapidly with pressure increasing.Our calculations indicate that helium can be quantitatively retained in aragonite in the deep mantle as long as the temperature is in the'stable temperature range'.These results have certain implications for exploring the evolution of mantle and the storage of helium within it.

关 键 词：Helium diffusion ARAGONITE High pressure Retention temperature Mantle evolution Geochemical evolution 

分 类 号：TG1[金属学及工艺—金属学]