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

Abstract

The substitution of aluminum with scandium in the mixed yttrium aluminum scandium garnets, Y 3 Sc x Al 5--x O 12 (x ¼ 0, 0.05, 0.5, 1.5), was studied for the first time using 27 Al magic angle spinning (MAS), multiple quantum (MQ) MAS NMR, and 45 Sc MAS NMR. The aluminum and scandium quadrupole coupling constants and isotropic chemical shifts were evaluated for all garnets under study. 27 Al 2D spectra evidenced variation of the isotropic shifts over the aluminum sites in the mixed garnets.

Composition‐Property‐Structure Correlations of Scandium Aluminosilicate Glasses Revealed by Multinuclear 45Sc, 27Al, and 29Si Solid‐State NMR

“…Given that we present the first 45 Sc NMR data from any crystalline or amorphous AS phase where Sc constitutes the sole (or even dominating) cation modifier, it is difficult to make unambiguous interpretations, but the average isotropic chemical shifts ≈92 ppm strongly suggest Sc [6] coordinations in our Sc–Al–Si–O specimens. The shifts conform well to the range 78–86 ppm observed for ScO 6 groups in crystalline silicates, and slightly higher than the value ppm reported from Y 3 Sc x Al 5− x O 12 ceramic phases . However, besides the Sc coordination number, the literature also indicates a nonnegligible dependence of the 45 Sc chemical shift on geometrical factors (e.g., Sc–O bond distances and O–Sc–O bond angles), as well as the identity of the cations in the second coordination sphere of Sc, in analogy with previous observations for Y .…”

“…Based on the observed 45 Sc isotropic NMR chemical shifts of ≈92 ppm, we attribute Sc to be present (primarily) in octahedral coordination . Given that our work represents the first 45 Sc NMR report from an AS glass where Sc 3+ constitutes the sole/main modifier ion, the present average 45 Sc isotropic chemical shifts (≈92 ppm), quadrupolar products (≈16 MHz), and chemical shift anisotropies (≈110 ppm) will serve as benchmark values for future investigations of Sc AS glasses.…”

“…The relatively few 45 Sc solid‐state NMR reports to date encompass studies of simple Sc salts/complexes, intermetallic compounds, ceramics, crystalline silicates, aluminophosphate glasses, and one Na 3 AlSi 3 O 9 glass incorporating 2 wt% Sc 2 O 3. The chemical shift of a cation depends foremost on the coordination number .…”

Sc2(MoO4)3 and Sc2(WO4)3: Halide Flux Growth of Single Crystals and 45Sc Solid-state NMR

“…Although these characteristics are excellent prerequisites for solid state NMR experiments, only few NMR spectroscopic reports can be found 0932-0776 / 10 / 0100-0013 $ 06.00 c 2010 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com in the literature, and little is known about the correlation of the 45 Sc NMR parameters with local structural data. Apart from an early work on intermetallic phases [7], which has been recently extended by us to other, more complex scandium-containing intermetallic systems [8 -11], several laboratories (including our own) have been examining oxidic systems [12 -24], contributing to the establishment of a comprehensive data base of 45 Sc NMR interaction parameters in inorganic materials. While the experiments of the present study were conducted, a publication by Kim and Stebbins appeared reporting 45 Sc chemical shift data on these materials and their solid solutions [24], however, their study did not address the nuclear electric quadrupolar interactions of the scandium nuclei.…”

Multinuclear Solid-State NMR Studies of Polymer-Supported Scandium Triflate Catalysts

“…= 100%) SSNMR to probe the structure of ME Sc(OTf) 3 . 45 Sc SSNMR has recently been employed to probe the structure of a variety of scandium-containing materials, − and the 45 Sc quadrupole tensors and chemical shifts have been found to be very sensitive to the structural differences in local Sc environments.…”