Nuclear magnetic resonance studies of ball-milled hydrides

详细信息	查看全文 | 推荐本文 |

• 作者：A.V. Skripov ; A.V. Soloninin ; A.L. Buzlukov ; A.P. Tankeyev ; A.Ye. Yermakov ; N.V. Mushnikov ; M.A. Uimin ; V.S. Gaviko
• 关键词：Metal hydrides ; Nanostructured materials ; Diffusion ; Nuclear resonances
• 刊名：Journal of Alloys and Compounds
• 出版年：2007
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：31 October 2007
• 卷：446-447
• 期：Complete
• 页码：489-494
• 文件大小：335 K

摘要

In order to study the effects of mechanical milling on the properties of metal hydrides, we have measured the proton nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates in two classes of nanostructured ball-milled systems: Laves-phase hydrides ZrCr₂H₃ and MgH₂-based hydrides with some additives (V₂O₅, Al). The proton NMR measurements have been performed at the resonance frequencies of 14, 23.8 and 90 MHz over the temperature range 11–420 K. Hydrogen mobility in the ball-milled ZrCr₂H₃ is found to decrease strongly with increasing milling time. The experimental data suggest that this effect is related to the growth of the fraction of highly distorted intergrain regions where H mobility is much lower than in the crystalline grains. For the MgH₂-based systems we have not found any effects of H jump motion at the NMR frequency scale up to 420 K. However, the measured proton spin-lattice relaxation rates for the nanostructured MgH₂-based samples appear to be several orders of magnitude higher than for the coarse-grained MgH₂. This relaxation rate enhancement can be attributed to the interaction between proton spins and intrinsic paramagnetic centers appearing in the process of ball milling.