71Ga Chemical Shielding and Quadrupole Coupling Tensors of the Garnet Y3Ga5O12from Single-Crystal71Ga NMR

Abstract
A single-crystal 71Ga NMR study of the garnet Y3Ga5O12 (YGG) has resulted in the determination of the first chemical shielding tensors reported for the 71Ga quadrupole. The single-crystal spectra are analyzed in terms of the combined effect of quadrupole coupling and chemical shielding anisotropy (CSA). 71Ga quadrupole coupling and CSA parameters for the two (tetrahedrally and octahedrally coordinated) gallium sites with axial symmetry in YGG (GaIV, CQ = 13.1 ± 0.2 MHz and δσ = 54 ± 50 ppm; GaVI, CQ = 4.10 ± 0.06 MHz and δσ = 24 ± 3 ppm) are fully consistent with its cubic crystal structure which supports the reliability of the experimental data. In addition, the 71Ga and 27Al isotropic chemical shifts for YGG and YAG give further support to the linear correlation observed earlier between 71Ga and 27Al isotropic chemical shifts.