A study of the electric quadrupole Raman processes of the proton‐conducting KHSeO4 and KDSeO4 single crystals using 1H, 2H and 39K NMR

Abstract

AbstractThe spin–lattice relaxation time, T1, and the spin–spin relaxation time, T2, of the 1H, 2H, and 39K nuclei in KHSeO4 and KDSeO4 crystals were determined in the temperature range 160–420 K. The T1 of the 39K nuclei in the two crystals were found to decrease with increasing temperature, and the spin–lattice relaxation rate, T1–1, for 39K is proportional to Tk. In the case of KHSeO4, T1–1 for the 39K nuclei was found to have a very strong temperature dependence, i.e. it is proportional to T7. The temperature dependence of the 39K relaxation rate in KDSeO4 is in accordance with a Raman process, as T1–1 ∝ T2. Thus, for the 39K nuclei in the two crystals, Raman processes with k = 2 and 7 is due to the coupling of electric quadrupole moments to the thermal fluctuations of the local electric field gradients. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)