Correlation between 19 F Environment and Isotropic Chemical Shift in Barium and Calcium Fluoroaluminates

M. Body (1) , G. Silly (2) , C. Legein (3) , J.-Y. Buzaré (4)

1 LPEC - Laboratoire de physique de l'état condensé
2 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 LdOF - Laboratoire des oxydes et fluorures
4 FRMN-SHC - Fédération RMN du Solide à Hauts Champs

High-speed MAS 19F NMR spectra are recorded and reconstructed for 10 compounds from BaF2−AlF3 and CaF2−AlF3 binary systems which leads to the determination of 77 isotropic 19F chemical shifts in various environments. A first attribution of NMR lines is performed for 8 compounds using a superposition model as initially proposed by B. Bureau et al. The phenomenological parameters of this model are then refined to improve the NMR line assignment. A satisfactory reliability is reached with a root-mean-square (RMS) deviation between calculated and measured values equal to 6 ppm. The refined parameters are then successfully tested on α-BaCaAlF7 whose structure was recently determined. Finally, the isotropic chemical shift ranges are defined for shared, unshared, and “free” fluorine atoms encountered in the investigated binary systems. So, the fluorine surroundings can be deduced from the NMR line positions in compounds whose structure is unknown. Such an approach can also be applied to fluoride glasses.

Domaines: Chimie inorganique

M. Body, G. Silly, C. Legein, J.-Y. Buzaré. Correlation between 19 F Environment and Isotropic Chemical Shift in Barium and Calcium Fluoroaluminates. Inorganic Chemistry, 2004, 43 (8), pp.2474-2485. ⟨10.1021/ic049956r⟩. ⟨hal-01984396⟩