7Li and 39K NMR relaxation study of a LiKSO4 single crystal Original Research Article

The 7Li and 39K NMR relaxations in a LiKSO4 single crystal grown by the slow evaporation method were investigated by employing a pulse NMR spectrometer. From the experimental data, the quadrupole coupling constant and asymmetry parameter were determined at the temperatures of 180 and 300 K. The relaxation processes of 7Li and 39K were studied for the LiKSO4 crystal, and the relaxation times for the 7Li and 39K nuclei exhibit remarkable changes near Tc2 (=190 K). The activation energies for 7Li and 39K were determined in phases I and III. The large change in the activation energy at 190 K indicates that the Li and K ions are significantly affected during this transition. The correlation time of the 7Li calculated from the spin-lattice relaxation time and quadrupole parameters was larger than that of the 39K calculated using the same method. The reason for this is that the Li ion undergoes molecular motion as in the LiO4 groups.