¹⁷O solid-state NMR spectroscopy of A₂B₂O₇oxides: quantitative isotopic enrichment and spectral acquisition?

Abstract

Investigation of the conditions required for quantitative isotopic enrichment and the acquisition of quantitative 17O NMR spectra of ceramic oxides.

Exploring cation disorder in mixed‐metal pyrochlore ceramics using 17O NMR spectroscopy and first‐principles calculations

“…For O2, larger C Q values are predicted by DFT calculations (ranging from 0.6 to 3.8 MHz), reflecting the lower symmetry of this site (and its OA2B2 coordination environment). Good agreement is also observed with the experimental values (and where it exists, with previous literature [16,40] ). It is noticeable, however, that when B = Sn (i.e., Y 2 Sn 2 O 7 and La 2 Sn 2 O 7 ) the C Q is considerably larger (3.3 MHz experimentally) than when B = Zr, Hf or Ti (0.7-1.5 MHz).…”

“…Spectra are shown after shearing and the δ 1 axis is referenced according to the convention of Pike et al [27] Fitting of the spectral lineshapes was carried out using the SOLA program (available within the Topspin software). Experimental intensities were compared to those in spectra simulated using the density matrix simulation program SIMPSON, [28] as described by Fernandes et al [16] Spectra were simulated at 14.1 T (under the experimental conditions described above) using detection operators of I 1x (i.e., all single-quantum coherences from the central transition (CT) and satellite transitions (ST)) or I 1c (i.e., only CT coherences), using 250 × 320 angles.…”

Mechanochemically assisted hydrolysis in the ADOR process

“…Comparing the experimental time required to acquire the spectra in Fig. 8a and b (2 h and 16 h, respectively) to those required in previous work for 17 O-enriched pyrochlores, 74 zeolites 75 , 76 and MOFs, 54 with enrichment levels (as determined by mass spectrometry) of 5–10%, 15–25% an 15–20%, respectively, suggests the levels of enrichment observed in the ball-milled ADOR products are approximately 10%. This is in excellent agreement with the maximum level of enrichment (calculated from the levels of 16 O and 17 O in all reagents) of ∼11%.…”

Ensemble-Based Modeling of the NMR Spectra of Solid Solutions: Cation Disorder in Y2(Sn,Ti)2O7

“…However, if the cell is sufficiently large to include the number of neighbors affecting the contributions to the NMR interactions of interest, a robust prediction of the complex NMR spectra can be obtained. Here, we demonstrate this using the Y 2 (Sn,Ti) 2 O 7 pyrochlore system (studied previously using 89 Y, 119 Sn and 17 O NMR spectroscopy) 11−17 as a case study. We show that these calculations allow a clear interpretation of the origin of the features in the NMR spectra of a solid solution, and provide insight into the atomic configurations that are present in the real material, and the importance each has in determining the appearance of the solid-state NMR spectrum.…”