Structural refinement of the RT LaOF phases by coupling powder X-Ray diffraction, 19F and 139La solid state NMR and DFT calculations of the NMR parameters

Abstract

The structures of the β- and t-LaOF phases have been refined from XRPD patterns. For both phases, ¹⁹F and ¹³⁹La solid-state NMR spectra recorded at high magnetic fields show the presence of a single F and a single La local environment, indicating a full anionic ordering in these oxyfluoride compounds. DFT calculations of the ¹⁹F and ¹³⁹La chemical shielding tensors and of the ¹³⁹La EFG tensor have been performed for the proposed structural models. The observed good agreement between experimental and calculated NMR parameters for both phases highlights the accuracy of the structural data.