GA-71 CHEMICAL SHIELDING AND QUADRUPOLE COUPLING TENSORS OF THE GARNET Y3GA5O12 FROM SINGLE-CRYSTAL GA-71 NMR

A single-crystal Ga-71 NMR study of the garnet Y3Ga5O12 (YGG) has resu lted in the determination of the first chemical shielding tensors repo rted for the Ga-71 quadrupole. The single-crystal spectra are analyzed in terms of the combined effect of quadrupole coupling and chemical s hielding anisotropy (CSA). Ga-71 quadrupole coupling and CSA parameter s for the two (tetrahedrally and octahedrally coordinated) gallium sit es with axial symmetry in YGG (Ga-IV, C-Q = 13.1 +/- 0.2 MHz and delta (sigma) = 54 +/- 50 ppm; Ga-VI, C-Q = 4.10 +/- 0.06 MHz and delta(sigm a) = 24 +/- 3 ppm) are fully consistent with its cubic crystal structu re which supports the reliability of the experimental data. In additio n, the Ga-71 and Al-27 isotropic chemical shifts for YGG and YAG give further support to the linear correlation observed earlier between Ga- 71 and Al-27 isotropic chemical shifts.