Nuclear magnetic resonance study of Li and H diffusion in the high-temperature solid phase of LiBH4

✍ Scribed by A.V. Soloninin; A.V. Skripov; A.L. Buzlukov; A.P. Stepanov

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 257 KB
• Volume: 182
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2009.06.023

✦ Synopsis

In order to study the atomic jump motions in the high-temperature solid phase of LiBH 4 , we have measured the 1 H and 11 B nuclear magnetic resonance (NMR) spectra and the 1 H, 7 Li and 11 B spin-lattice relaxation rates in this compound over the resonance frequency range of 14-34.4 MHz. In the temperature range 384-500 K, all the spin-lattice relaxation data are satisfactorily described in terms of a thermally activated jump motion of Li ions with the pre-exponential factor t 0 ¼ 1.1 Â10 À15 s and the activation energy E a ¼ 0.56 eV. The observed frequency dependences of the spin-lattice relaxation rates in this temperature range exclude a presence of any distributions of the Li jump rate or any other jump processes on the frequency scale of 10 7 -10 10 s À1 . The strong narrowing of the 1 H and 11 B NMR lines above 440 K is consistent with the onset of diffusive motion of the BH 4 tetrahedra.