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Activation energy barriers for Na migration in Na12A zeolite: The main contribution to ionic current via doubly occupied NaII site?
Microporous and Mesoporous Materials ( IF 4.8 ) Pub Date : 2020-06-13 , DOI: 10.1016/j.micromeso.2020.110288
A.A. Rybakov , D.N. Trubnikov , A.V. Larin

The activation barriers for Na jumps between the cationic sites NaI, NaII, and NaIII are calculated using VASP in the presence of anions (Cl, Br) or H2O as well as for the empty Na12A zeolite model. The inter-cage cationic NaIII→NaII’→NaIII′ path, where NaIII′ is located in the neighbor α–cage, was modeled via an intermediate state (NaII′) corresponding to two NaII cations in one 8R window. This NaII′ point can also serve as an intermediate for the second type of intra-cage Na drift, i.e., to a NaIII site in the same cage. Reasonable agreement with experimental activation energy was achieved for NaII’→NaIII′, NaII→NaIII, and NaIII→NaIII jumps. The lower activation energy is obtained for the NaII’→NaIII' jump than for NaII→NaIII, which indicates the possible role of the doubly occupied 8R window as an intermediate state in the Na transfer with high frequency and lower activation energy related to ionic current (inter-cage transfer) in Na12A.



中文翻译:

Na 12 Na沸石中Na迁移的活化能垒:通过双重占据的NaII位点对离子电流的主要贡献?

的Na活化障碍的阳离子位点的NaI,NAII,和NaIII在阴离子的存在下使用VASP计算(CL之间跳跃- ,溴-或H)2 O作为以及为空的Na 12沸石模型。笼间阳离子NaIII→NaII'→NaIII'路径(其中NaIII'位于相邻的α-笼中)是通过一个8R窗口中对应于两个NaII阳离子的中间状态(NaII')建模的。该NaII'点还可以用作第二种笼内Na漂移的中间体,到同一笼子里的NaIII站点。NaII'→NaIII',NaII→NaIII和NaIII→NaIII跃变与实验活化能达到了合理的一致性。NaII'→NaIII'跳跃获得的活化能比NaII→NaIII更低,这表明双占据的8R窗作为Na转移的中间状态的可能作用是高频的,而与离子电流相关的活化能较低(笼间转移)在Na 12 A中。

更新日期:2020-06-23
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