Structure, conductivity, and ionic motion in $Na{_1+x}Zr{_2}SixP{_3-x}O1{_2}:$ A simulation study
Structure, conductivity, and ionic motion in $Na{_1+x}Zr{_2}SixP{_3-x}O1{_2}:$ A simulation study
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DOI：
10.1021/jp020287h
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发表时间：
2002-06
期刊：
影响因子：
--
通讯作者：
P. P. Kumar-P.;S. Yashonath
中科院分区：
文献类型：
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作者：
P. P. Kumar-P.;S. Yashonath
采用恒压、恒温变形模拟胞MonteCarlo和微正则系综分子动力学方法，对600 K下超离子导电菱面体相Na_（1 + x）Zr_2Si_（3-x）O_（12），0 ≤ x ≤ 3进行了模拟。讨论了结构、导电性、跳跃路径、占位性、骨架原子键长随组成的变化。平均Na（1）-O距离在x = 2处显示出峰值，而Na（2）-O距离显示出单调增加。在Na（1）和中间Na位点的钠占位符的总和加起来为恒定值1，这支持Boilot等人的结论。(1)基于X射线衍射。Na（1）位的占有率在x = 2时达到最小值。发现主要的传导通道（其携带超过90%的钠离子）是连接Na（1）-mid-Na-Na（2）的通道。密度等值线钠，描绘这个传导通道，报告。自由能分布沿着传导通道表明熵的贡献不能忽略。中间钠网站是不相关的自由能最小值。
Constant-pressure, constant-temperature variable-shape simulation cell Monte Carlo and microcanonical ensemble molecular dynamics simulation of superionic conducting rhombohedral phase of Nasicon, Na1+xZr2Si3-xO12, 0 less than or equal to x less than or equal to 3, at a temperature of 600 K is reported. Changes in structure, conductivity, hop path, site occupancies, bond lengths of framework atoms with composition are discussed. Average Na(1)-O distance shows a peak at x = 2, while Na(2)-O distance shows a monotonic increase. Sum of the sodium occupancies at Na(l) and mid-Na sites adds up to a constant value of one which supports the conclusion of Boilot et al.(1) based on X-ray diffraction. Occupancy of Na(l) site attains a minimum at x = 2. The predominant conduction channel (which carries more than 90% of the sodium ions) is found to be the one connecting Na(1)-mid-Na-Na(2). Density contours for sodium, depicting this conduction channel, are reported. Free energy profile along the conduction channel suggests that entropy contribution cannot be neglected. The mid-Na site is not associated with a free energy minimum.