Structural Study of La_1–xY_xScO₃, Combining Neutron Diffraction, Solid-State NMR, and First-Principles DFT Calculations

Abstract

The solid-solution La 1−x Y x ScO 3 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) has been successfully synthesized using conventional solid-state techniques. Detailed structural characterization has been undertaken using high-resolution neutron powder diffraction and multinuclear resulting from distributions of both quadrupolar and chemical shift parameters, owing to the disordered nature of the material. In contrast to previous single crystal studies, which reveal small deficiencies at both the lanthanide and oxygen sites, the powder samples studied herein are found to be stoichiometric.

Unravelling the Mystery of Solid Solutions: A Case Study of 89Y Solid‐State NMR Spectroscopy

“…It is unclear if a preference for A or B sites is present. Lightfoot, Ashbrook, and co‐workers investigated the Y distribution in La 1− x Y x ScO 3 by 89 Y SSNMR spectroscopy . As Figure illustrates, the pure YScO 3 phase exhibits a single sharp peak at 263.3 ppm, consistent with the presence of a single Y site.…”

“…89 Y isotropic chemical shift and full‐width‐at‐half‐maximum (FWHM) values are also shown. Adapted with permission . Copyright 2013, American Chemical Society.…”

New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

“…92 For this latter case, as shown in Figure 6, the comparison of a range of 27 Al and 31 P NMR spectra, with the NMR parameters calculated for models with differing hydroxyl positions was able to show that hydroxyls bridge between Al1 and Al2 in the cancrinite cages, but that two hydroxyls do not occupy the same cage simultaneously. 90…”

27Al NMR Studies of Aluminosilicate Glasses

“…Moreover, their higher quadrupolar moments of Q j j¼ 22:0 fm 2 ( 45 Sc) and Q ¼ 20.0 fm 2 ( 139 La) may induce very substantial quadrupolar coupling constants spanning tens of MHz. Consequently, while 45 Sc MAS NMR was only recently demonstrated on glasses [116,128,129], the few current 139 La MAS applications involved either highly symmetric La environments in ordered/crystalline structures [130][131][132][133][134], or NMR on static powders of metallocenes [135] or ceramics [136], for which very high 139 [51], no 139 La MAS NMR results are to our knowledge reported from glasses, presumably owing to a substantial CT signal broadening stemming from very large C Q values and the modest magnetogyric ratio of 139 La (which is close to that of 17 O). Moreover, significant distributions of both C Qη and δ iso parameters are expected to deteriorate the NMR signal resolution and sensitivity further.…”