Dynamic Behavior of Group 13 Elements in Bromocomplexes as Studied by NQR and NMR

NMR, NQR, powder X-ray diffraction, DTA and AC conductivity were measured in RMBr4 (R = Ag, Cu; M = Al, Ga) and RM2Br7 (R = Li, Ag; M = Al, Ga). In RMBr4, the activation energy of Cu diffusion was evaluated fromCu NMR and was in good agreement with that fromBr NQR. In CuAlBr4, the e Qq/h value of Cu NMR and the value of Al NMR changed linearly with decreasing temperature, although the eQq=h value of Al NMR did not change so much. These temperature dependences are supposed to be due to Cu diffusion and not to a variation of the lattice constants. In RM2Br7, the activation energy was obtained from the spin-lattice relaxation time T1 of Br NQR and is ascribed to a modulation of the cation diffusion. The line width ofLi NMR in LiAl2Br7 was about 5.9 kHz in the low-temperature phase and 0.4 kHz for the high-temperature phase. The Al NMR spectrum was broadened by the quadrupole interaction and unchanged up to 400 K, suggesting that diffusion of Li ions occurs in the high-temperature phase.