Structural Study of La1-xYxScO3, Combining Neutron Diffraction, Solid-State NMR, and First-Principles DFT Calculations

The solid solution La1-xYxScO3 (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 (Sc-45, La-139, Y-89, and O-17) solid-state NMR and is supported by first-principles density functional theory calculations. Diffraction data indicate that a reduction in both the unit cell parameters and unit cell volume is observed with increasing x, and an orthorhombic perovskite structure (space group Pbnm) is retained across the series. Sc-45 multiple-quantum (MQ) MAS NMR spectra proved to be highly sensitive to subtle structural changes and, in particular, cation substitutions. NMR spectra of La1-xYxScO3 exhibited significant broadening, 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.