The temperature dependence of 7Li nuclear magnetic resonance in a LiRbSO4 single crystal

The temperature dependence of the 7Li nuclear magnetic resonance in a LiRbSO4 single crystal grown by the slow-evaporation method has been investigated by employing a Bruker FT NMR spectrometer. The three-line structure due to the quadrupole interaction was measured in three mutually perpendicular crystal planes. From the experimental data, the quadrupole coupling constant, e2qQ/h = 20.4±0.2 kHz, and asymmetry parameter, η=0, are determined at room temperature. The principal axes of the EFG tensor are parallel to the crystallographic a-, b-, and c-axes. The largest principal axis Z is parallel to the crystallographic c-axis. In the temperature range 140-400 K, the nuclear quadrupole coupling constant of Li in LiRbSO4 decreases as the temperature increases. The temperature dependence of the quadrupole parameters is satisfactorily explained with a single torsional frequency of the Li-O ion by means of the simple Bayer theory. (author)