Metallic and non-metallic lanthanum hydrides studied by means of nuclear magnetic resonance

Abstract

139 La nuclear magnetic resonance ( T 1, linewidth) is measured for lanthanum hydrides LaH x (2.0≤ x≤3.0) at temperatures between 4 K and 300 K at a Larmor frequency of 42.44 MHz. Resonance line narrowing and the increase of the spin-lattice relaxation rate for temperatures above 200 K, originating from the well-established type of thermally activated proton hopping motion in lanthanum hydrides, are observed. A Korringa relaxation contribution is separated in the low-temperature range ( T≤80 K) for the dihydride as well as for the samples LaH x in the concentration range, where the metal–non-metal transition is suggested to occur.