The crystal structure was determined by means of the Rietveld analysis of X-ray powder diffraction data. It belonged to a tetragonal system in which both the Al and Cu atoms were surrounded tetrahedrally by 4 halogen atoms. The Al-Br and Cu-Br bond lengths were 0.226 and 0.245nm, respectively. Nuclear magnetic resonance studies of monocrystals, using 63Cu, suggested that the principal axis of the e2Qg/h tensor was parallel to the c-axis. The quadrupole coupling constant was estimated to be 0.35MHz. The temperature dependences of line-widths and line-shapes indicated that the activation energy for Cu+ diffusion was 46.4kJ/mol. The spin-lattice relaxation times of the 81Br NQR signals were also affected by Cu+ diffusion.

Cation Self-Diffusion in MAlX4 (M = Cu, Ag; X = Cl, Br) Studied by X-Ray Diffraction, 63Cu NMR and Halogen NQR. K.Yamada, Y.Tomita, T.Okuda: Journal of Molecular Structure, 1995, 345, 219-27

Table 13

Diffusivity of Cu+ in Various Phases of CuBr