Superprotonic conductor CsH2PO4 studied by 1H, 31P NMR and X-ray diffraction
Superprotonic conductor CsH2PO4 studied by 1H, 31P NMR and X-ray diffraction
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DOI：
10.1016/j.ssi.2004.03.042
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发表时间：
2004-11-30
影响因子：
3.2
通讯作者：
Okuda, T
中科院分区：
文献类型：
--
作者：
Yamada, K;Sagara, T;Okuda, T
通过X射线衍射和固态NMR研究了CsH2PO4的顺电相到超离子相变。 H-1 NMR 粉末光谱显示出特征性的高场位移（相对于 H2O 为 8.0 ppm），正如质子形成强氢键所预期的那样。 H-1 和 P-31 NMR 的温度依赖性表明 H2PO4- 阴离子在 420 K 以上会发生重新取向跳跃。H2PO4- 阴离子的重新取向跳跃也通过使用单晶的 P-31 NMR 得到证实，并且通过光谱模拟估计活化能为 4 为 0.74(1) eV。在 502 K 的超离子相变以上，通过 Rietveld 分析以及 H-1、P-31 NMR 的各向同性清晰光谱证实了动态无序的 PO4 单元。这些观察结果表明，即使在顺电相中，H2PO4-阴离子的重新定向对于质子传导也起着重要的作用。 (C) 2004 Elsevier B.V. 保留所有权利。
Paraelectric to superionic phase transition of CsH2PO4 was studied by means of X-ray diffraction and solid-state NMR. H-1 NMR powder spectrum showed the characteristic high field shift (8.0 ppm relative to H2O) as is expected for the proton forming a strong hydrogen bonding. The temperature dependence of the H-1 and P-31 NMR suggests a reorientational jump of the H2PO4- anion above 420 K. The reorientational jump of the H2PO4- anion was also confirmed by the P-31 NMR using a single crystal and the activation energy was estimated 4 to be 0.74(1) eV by the spectrum simulation. Above the superionic phase transition at 502 K, a dynamically disordered PO4 unit was confirmed by the Rietveld analysis and also by the isotropic sharp spectra of the H-1, P-31 NMR. These observations suggest that the reorientation of the H2PO4- anion plays air important role for the proton conduction even in the paraelectric phase. (C) 2004 Elsevier B.V. All rights reserved.