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首页> 外文期刊>Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics >NMR studies of hydrogen diffusion in ZrBe2H1.4
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NMR studies of hydrogen diffusion in ZrBe2H1.4

机译：ZrBe2H1.4中氢扩散的NMR研究

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The diffusivity of hydrogen in the metal-hydride ZrBe2H1.4 has been studied by different nuclear magnetic resonance (NMR) techniques. The proton spin-lattice relaxation rate Gamma(1) has been measured at 27.7 MHz and 67.7 MHz in the temperature range from 175 K to 500 K. At four distinct temperatures the frequency dependence of Gamma(1) has been investigated between 0.31 MHz and 29.2 MHz using the field-cycling (FC) NMR technique. These studies indicate that the hydrogen diffusion is restricted to two dimensions within each particle of the powdered sample. The structure of ZrBe2H1.4 suggests that. the hydrogen diffusion takes place in the xy planes formed by the Zr atoms. The variation of the echo amplitude with the applied field gradient in pulsed-held-gradient (PFG) spin-echo experiments confirmed the two-dimensional character of the hydrogen diffusion. The PFG data taken between 272 K and 478 K yielded directly the diffusivities in the xy plane D-xy. The temperature dependence of D-xy is well represented by an Arrhenius law with an activation enthalpy H-a=(0.25+/-0.02) eV. This activation enthalpy is in very good agreement with values deduced from both the frequency and the temperature dependence of Gamma(1). (C) 1998 Elsevier Science S.A. [References: 27]
机译：氢在金属氢化物ZrBe2H1.4中的扩散率已通过不同的核磁共振（NMR）技术进行了研究。在175 K至500 K的温度范围内，在27.7 MHz和67.7 MHz处测量了质子自旋晶格弛豫率Gamma（1）。在四个不同的温度下，已经研究了Gamma（1）在0.31 MHz至500 MHz之间的频率依赖性。使用场循环（FC）NMR技术的29.2 MHz。这些研究表明，在粉末状样品的每个颗粒内，氢的扩散被限制为二维。 ZrBe2H1.4的结构表明。氢扩散发生在Zr原子形成的xy平面上。在脉冲保持梯度（PFG）自旋回波实验中，回波振幅随施加的场梯度的变化证实了氢扩散的二维特征。在272 K和478 K之间获取的PFG数据直接产生了xy平面D-xy中的扩散率。 D-xy的温度依赖性由阿伦尼乌斯定律很好地表示，活化焓H-a =（0.25 +/- 0.02）eV。该激活焓与从Gamma（1）的频率和温度依赖性得出的值非常吻合。 （C）1998 Elsevier Science S.A. [参考：27]

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