Dehydration dynamics of bikitaite: Part II. Ab initio molecular dynamics study

被引:36
作者
Ceriani, C [1 ]
Fois, E
Gamba, A
Tabacchi, G
Ferro, O
Quartieri, S
Vezzalini, G
机构
[1] Dipartimento Sci Chim, Via Lucini 3, I-22100 Como, Italy
[2] Dipartimento Sci Terra, I-41100 Modena, Italy
[3] Dipartimento Sci Terra, I-98166 Messina, Italy
关键词
D O I
10.2138/am-2004-0113
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
High-temperature behavior and the process of thermal dehydration in the natural zeolite bikitaite have been studied by ab initio molecular dynamics simulations, and favorably compared with the X-ray powder diffraction data presented in Part I of this work (Ferro et al. 2003). The microscopic dynamical behavior of the extraframework species (water molecules and Li cations) has been characterized as a function of temperature. Two regimes have been detected, and the transition is characterized by the breaking of the one-dimensional water chain typical of bikitaite at room temperature. The elementary steps for the diffusion of water inside the bikitaite channels have been studied by means of a rare-events-sampling technique (Bluemoon Ensemble). The activation free-energy for a site-to-site water jump has been calculated and a mechanism for the dehydration process is proposed.
引用
收藏
页码:102 / 109
页数:8
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