Aluminium–Gallium Substitution in Yttrium Garnets Investigated by NMR and X-Ray Absorption

Abstract

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.

27Al and45Sc NMR Studies of the Y3ScxAl5?xO12 Mixed Garnets

“…The 27 Al MAS spectra obtained for the pure yttrium aluminum garnet were similar to those published earlier [8][9][10]. For the octahedral site, one can see the central line and all sidebands corresponding to satellite transitions (AE1/2 $ AE3/2 and AE3/2 $ AE5/2), while for the tetrahedral site only the central line and several near sidebands are observable because of stronger quadrupole coupling for this site (Fig.…”

“…The spectra can be well fitted with the parameters listed in Table 1 when the asymmetry parameter is assumed to be equal to 0. The chemical shifts were similar to those measured in [8][9][10]. The chemical shifts were similar to those measured in [8][9][10].…”

“…1). The nuclear quadrupole coupling constants, e 2 qQ/h [4] (e is the electron charge, eq is the zz component of the electric field gradient tensor, Q is the nuclear quadrupole moment, and h is the Planck constant), were the same within the experimental accuracy as in [8][9][10][11][12][13] for both tetrahedral and octahedral sites. The nuclear quadrupole coupling constants, e 2 qQ/h [4] (e is the electron charge, eq is the zz component of the electric field gradient tensor, Q is the nuclear quadrupole moment, and h is the Planck constant), were the same within the experimental accuracy as in [8][9][10][11][12][13] for both tetrahedral and octahedral sites.…”

Aluminum and Gallium Substitution in Yttrium and Lutetium Aluminum–Gallium Garnets: Investigation by Single-Crystal NMR and TSL Methods

“…Owing to their similar ionic radii, aluminum and gallium atoms have been found in both tetrahedral and octahedral coordinations in oxide compounds. , The ease of aluminum–gallium substitution has been a subject of several studies where the preference of Ga 3+ with respect to Al 3+ for tetrahedral site occupation has been observed ,,, and theoretically calculated in garnets . This preference cannot be explained by a size effect since the gallium ionic radius is larger than that of aluminum.…”

Sol–gel synthesis, characterization and study of substitution effects in different gallium-containing garnets

“…By selecting corresponding lanthanide ions may be produced red, green and blue (RGB) emission for use in tricolour white light [25][26][27]. In the YAG, all aluminium ions may be substituted by gallium or iron ions [28][29][30], while pure yttrium indium or yttrium scandium garnet is not obtained. The substitution limits on yttrium gallium scandium and yttrium aluminium gallium scandium mixed-metal garnets were discussed by Muliuoliene et al [31], Garskaite et al [32] and Skaudzius et al [33].…”