Enabling materials informatics for 29Si solid-state NMR of crystalline materials

Abstract

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for obtaining precise information about the local bonding of materials, but difficult to interpret without a well-vetted dataset of reference spectra. The ability to predict NMR parameters and connect them to three-dimensional local environments is critical for understanding more complex, long-range interactions. New computational methods have revealed structural information available from 29 Si solid-state NMR by generating computed reference spectra for solids. Such predictions are useful for the identification of new silicon-containing compounds, and serve as a starting point for determination of the local environments present in amorphous structures. In this study, we have used 42 silicon sites as a benchmarking set to compare experimentally reported 29 Si solid-state NMR spectra with those computed by CASTEP-NMR and Vienna Ab Initio Simulation Program (VASP). Data-driven approaches enable us to identify the source of discrepancies across a range of experimental and computational results. The information from NMR (in the form of an NMR tensor) has been validated, and in some cases corrected, in an effort to catalog these for the local spectroscopy database infrastructure (LSDI), where over 10,000 29 Si NMR tensors for crystalline materials have been computed. Knowledge of specific tensor values can serve as the basis for executing NMR experiments with precision, optimizing conditions to capture the elements accurately. The ability to predict and compare experimental observables from a wide range of structures can aid researchers in their chemical assignments and structure determination, since the computed values enables the extension beyond tables of typical chemical shift (or shielding) ranges.

Local Structure of Glassy Lithium Phosphorus Oxynitride Thin Films: A Combined Experimental and Ab Initio Approach

“…The CSA reflects the distortion of the electronic structure around the nucleus and contains information regarding the local symmetry of said nucleus, which is fully described by two parameters, anisotropy Δδ and asymmetry η (see SI for full convention definition). The chemical shift tensor elements are also included (Table S5 and S8) to verify the accuracy of the CSA parameters and mitigate the assignment error that the Haeberlen convention is prone to (Δδ and η ) [39] . These CSA parameters provide distinction of different structures based on their local symmetry despite having similar chemical shifts.…”

“…Thec hemical shift tensor elements are also included (Table S5 and S8) to verify the accuracyo ft he CSA parameters and mitigate the assignment error that the Haeberlen convention is prone to (Dd and h). [39] These CSA parameters provide distinction of different structures based on their local symmetry despite having similar chemical shifts. CSA analysis is especially useful for disordered structures as it provides the means to distinguish different chemical environments despite overlapping resonances.…”

Local Structure of Glassy Lithium Phosphorus Oxynitride Thin Films: A Combined Experimental and Ab Initio Approach

“…Thec hemical shift tensor elements are also included (Table S5 and S8) to verify the accuracy of the CSA parameters and mitigate the assignment error that the Haeberlen convention is prone to (Dd and h). [39] These CSA parameters provide distinction of different structures based on their local symmetry despite having similar chemical shifts.C SA analysis is especially useful for disordered structures as it provides the means to distinguish different chemical environments despite overlapping resonances. [36,40,41] Thec alculated d iso and CSA parameters are grouped by their corresponding Q n m speciation ( Figure 3…”

Improved Understanding of Atomic Ordering in Y4SixAl2–xO9–xNx Materials Using a Combined Solid-State NMR and Computational Approach

“…For 27 Al, 17 O, 29 Si and 15 N there is a high degree of correlation (R 2 ≈ 1), comparable with that obtained in the literature. [44][45][46] For 89 Y our correlation is not quite as good; a higher degree of correlation has been achieved in the literature using a broader dataset, but is sufficient for accurate assignment. 47,48 Structural parameters, atomic coordinates and unit cell parameters were obtained from experimental crystal structures in the literature.…”