Nuclear quadrupole interactions of11B ina LiB3O5 single crystal

Abstract

The rotation patterns of the nuclear magnetic resonance (NMR) spectra of an11B nucleusin a LiB3O5 (LBO) single crystal were measured in the three mutually perpendicularcrystallographic planes at room temperature. We identified three centresdenoted as B1, B2, and B3, each of which consists of four sets of11B NMR spectra originating from the chemically equivalent but magnetically inequivalentsites. The four sets belonging to each centre were properly classified in accordance withcrystal symmetry and analysed. The principal values and principal axis orientations of thenuclear quadrupole coupling (NQC) tensors were determined for the first time. The centresB1, B2, and B3 were assigned to boron sites in the crystalline lattice of LBO bycomparing the directions of the B–O bonds and the principal axes of the NQC tensor(P). The NQC constant(e2qQ/h) and asymmetry parameter(η) were determinedas follows: for B1, e2qQ/h = 2.615 ± 0.005 MHz and η = 0.266 ± 0.005; for B2, e2qQ/h = 0.176 ± 0.003 MHz and η = 0.584 ± 0.003;and for B3, e2qQ/h = 2.690 ± 0.004 MHz and η = 0.204 ± 0.003.