Anion Rotation and Cation Diffusion in Low-Temperature Sodium Orthophosphate: Results from Solid-State NMR
Anion Rotation and Cation Diffusion in Low-Temperature Sodium Orthophosphate: Results from Solid-State NMR
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低温正磷酸钠中的阴离子旋转和阳离子扩散：固态 NMR 结果
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
M. Jansen
中科院分区：
文献类型：
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作者：
M. Witschas;H. Eckert;H.;A. Putnis;G. Korus;M. Jansen
已知许多离子晶体，其中阳离子和阴离子在固态下都具有相当大的迁移率。在过去的十年中，有相当大的争议的问题，是否阳离子和阴离子运动可以动态耦合在这样的材料。高温（HT-）Na_3 PO_4是一种塑性结晶材料，在600 K附近发生一级相变，经低温改性后形成。在本研究中，低温相的动力学特征已全面的补充NMR方法。温度依赖的17 O NMR线形分析表明，磷酸根离子经历3倍旋转的时间尺度上的毫秒。然而，似乎有一个首选的旋转轴。变温23 Na和31 P NMR谱进一步揭示了钠阳离子表现出相当大的流动性。阴离子和阳离子的运动似乎是共同的热…
Numerous ionic crystals are known in which both cations and anions possess considerable mobility in the solid state. During the past decade, there has been considerable controversy about the question of whether cationic and anionic motion can be dynamically coupled in such materials. This issue has been studied recently on the plastic crystalline material high-temperature (HT-) Na3PO4, which forms from the low-temperature modification in a first-order phase transition at a temperature near 600 K. In the present study, the dynamics of the low-temperature phase have been characterized comprehensively by complementary NMR methods. Temperature-dependent 17O NMR line shape analyses indicate that the phosphate ions undergo 3-fold rotation on the time scale of milliseconds. There appears to be one preferred axis of rotation, however. Variable-temperature 23Na and 31P NMR spectra reveal further that the sodium cations exhibit considerable mobility. Both anionic and cationic motion appear to be jointly thermally a...