Combined NMR and X-ray diffraction study of structural aspects, dynamics and charge ordering mechanism in LixVOPO4.2H2O intercalation compounds

R Boulé; C Kouvatas; C Roiland; T Bataille; V Alonzo; E Le Fur; L Le Pollès

doi:10.1016/j.ssnmr.2019.101623

Combined NMR and X-ray diffraction study of structural aspects, dynamics and charge ordering mechanism in Li_xVOPO₄.2H₂O intercalation compounds

Solid State Nucl Magn Reson. 2019 Dec:104:101623. doi: 10.1016/j.ssnmr.2019.101623. Epub 2019 Oct 22.

Authors

R Boulé¹, C Kouvatas¹, C Roiland¹, T Bataille¹, V Alonzo¹, E Le Fur¹, L Le Pollès²

Affiliations

¹ Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR - UMR 6226, F- 35000, Rennes, France.
² Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR - UMR 6226, F- 35000, Rennes, France. Electronic address: laurent.le-polles@ensc-rennes.fr.

PMID: 31678745
DOI: 10.1016/j.ssnmr.2019.101623

Abstract

We carried out a detailed investigation of the local ordering and dynamics of the lithium intercalation in paramagnetic Li_xVOPO₄.2H₂O (with 0 < x ≤ 1) materials. This question was addressed using a combination of X-ray diffraction, ³¹P and ⁷Li MAS NMR experiments. We first studied the structure of the fully ordered end-member of the series, Li₁VOPO₄.2H₂O, revisiting the X-ray single crystal diffraction data on the basis of the information provided by ³¹P MAS NMR. We then carried out ⁷Li MAS and exchange NMR experiments and ³¹P MAS experiments on the polycrystalline powders obtained after partial lithium insertion in VOPO₄.2H₂O phases. These experiments evidenced an unexpected ageing of the material related with lithium dynamics between the VOPO₄ layers and a V⁴⁺/V⁵⁺ charge ordering mechanism within the layers.

Keywords: (7)Li EXSY NMR; (7)Li and (31)P MAS NMR; Dynamics; Intercalation compounds; Local ordering; X-ray diffraction.