Li-7 and Rb-87 nuclear magnetic resonance in a LiRbSO4 single crystal with the growth twin domain

Abstract

The Li-7 and Rb-87 NMR in a LiRbSO4 single crystal with the growth twin domain grown by the slow evaporation method were investigated by employing a Bruker FT NMR spectrometer. Instead of the simple one set of signals caused by quadrupole interaction, three sets of NMR signals were obtained. From these results, all parameters were determined, and all lead to the same values for the quadrupole coupling constant and asymmetry parameter. The Li-7 NMR parameter in the LiRbSO4 crystal was axially symmetric, whereas the Rb-87 NMR parameter was non-axially symmetric; the lithium ion is surrounded by oxygen atoms located on a regular tetrahedron, and the resultant coordinating rubidium ion is surrounded by slightly distorted oxygen atoms located at nine regular tetrahedra. The obtained results can be explained by the existence of three kinds of growth twin domain, rotated with respect to each other by 120 degrees around the c-axis.