New perspectives on calcium environments in inorganic materials containing calcium-oxygen bonds: A combined computational-experimental 43Ca NMR approach.
Résumé
The potential of a combined experimental-computational 43Ca solid state NMR approach for the structural analysis of different families of inorganic compounds (calcium phosphates, silicates, aluminates and borates) was studied. Natural-abundance 43Ca NMR data of six crystallographic calcium phosphates is reported. DFT periodic calculations of 43Ca NMR parameters of an extensive number of Ca-O inorganic species were performed, showing that the isotropic chemical shift of calcium can accurately be predicted. A strong dependence of the isotropic chemical shift on the average Ca...O bond distance and on the nature of the associated oxoanion is found.