Quasi‐One‐Dimensional Behaviour of Hydrogen in H_0.35MoO₃ and H_0.33WO₃ as Revealed by Proton NMR

Abstract

Abstract The 1 H NMR has been studied in the hydrogen bronzes H 0.35 MoO 3 and H 0.33 WO 3 prepared by galvanostatic cathodic reduction. Both systems reveal an extreme anisotropy of the hydrogen mobility due to quasi‐one‐dimensional behaviour. – In H 0.35 MoO 3 the temperature dependent 1 H wideline data give strong evidence that hydrogen is clustered in quasi‐one‐dimensional channels. Analysis of the temperature dependence of the second moment M 2 , the transverse relaxation time T 2 , and the spin‐lattice relaxation time T 1 yields essentially the same value E A = 30 kJ/mol for the activation energy of the translational motion of hydrogen within the channels. In H 0.33 WO 3 evidence for the quasi‐one‐dimensional behaviour is provided by the frequency dependence of T 1 and the marked non‐exponential recovery of the nuclear magnetization in the vicinity of the T 1 minimum. The activation energy for the translational motion is E A = 3.6 kJ/mol only, indicating high mobility of hydrogen in this bronze.