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A single-crystal (71)Ga NMR study of the garnet Y(3)Ga(5)O(12) (YGG) has resulted in the determination of the first chemical shielding tensors reported for the (71)Ga quadrupole. The single-crystal spectra are analyzed in terms of the combined effect of quadrupole coupling and chemical shielding anisotropy (CSA). (71)Ga quadrupole coupling and CSA parameters for the two (tetrahedrally and octahedrally coordinated) gallium sites 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(sigma) = 24 +/- 3 ppm) are fully consistent with its cubic crystal structure which supports the reliability of the experimental data. In addition, the (71)Ga and (27)Al isotropic chemical shifts for YGG and YAG give further support to the linear correlation observed earlier between (71)Ga and (27)Al isotropic chemical shifts.

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Y3Al5O12 (YAG), Y3Ga5O12 (YGG) and mixed Y3Al5—xGaiixO12 (x = 0.5, 1, 2, 3, 4.5) have been synthesised by a sol–gel process. From the X‐ray diffraction analysis the crystallised powders were shown to present a garnet structure with unit cell parameters agreeing well with those of single crystals. The aluminium–gallium substitution of the garnet structure has been studied by NMR and EXAFS techniques.

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