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

Abstract

The spin-lattice relaxation time, T(1), and the spin-spin relaxation time, T(2), of the (1)H, (2)H, and (39)K nuclei in KHSeO(4) and KDSeO(4) crystals were determined in the temperature range 160-420 K. The T(1) of the (39)K nuclei in the two crystals were found to decrease with increasing temperature, and the spin-lattice relaxation rate, T(1)(-1), for (39)K is proportional to T(k). In the case of KHSeO(4), T(1)(-1) for the (39)K nuclei was found to have a very strong temperature, dependence, i.e. it is proportional to T(7). The temperature dependence of the (39)K relaxation rate in KDSeO(4) is in accordance with a Raman process, as T(1)(-1) proportional to T(2). Thus, for the (39)K 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. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.