NMR study of one-dimensional ionic conductor with hollandite-type structure. II. Frequency dependence of spin-lattice relaxation time of 27Al

Abstract

Frequency dependence of spin-lattice relaxation time T 1 of 27Al in one-dimensional K + ion conductor, K-Al-priderite, was measured at 45 K in the frequency range from 10.1 MHz to 55 MHz. It is found that T 1 is proportional to ω 1.49±0.05 and agrres well with the ω 3 4 dependence derived by the continuum diffusion model. The intrinsic activation energy is determined to be 0.058 eV by doubling the slope E NMR=0.029 eV of the d(ln T 1)/d T curve in the low temperature region. The frequency dependence of T 1 in the high temperature region measured in the frequency range from 11.5 MHz to 20.8 MHz shows a tendency that the frequency dependence becomes smaller than the ω 1 2 dependence as temperature is raised above 450 K.