First principles NMR study of fluorapatite under pressure

Abstract

NMR is the technique of election to probe the local properties of materials. Herein we present the results of density functional theory (DFT) ab initio calculations of the NMR parameters for fluorapatite (FAp), a calcium orthophosphate mineral belonging to the apatite family, by using the GIPAW method [Pickard and Mauri, 2001]. Understanding the local effects of pressure on apatites is particularly relevant because of their important role in many solid state and biomedical applications. Apatites are open structures, which can undergo complex anisotropic deformations, and the response of NMR can elucidate the microscopic changes induced by an applied pressure. The computed NMR parameters proved to be in good agreement with the available experimental data. The structural evaluation of the material behavior under hydrostatic pressure (from −5 to +100 kbar) indicated a shrinkage of the diameter of the apatitic channel, and a strong correlation between NMR shielding and pressure, proving the sensitivity of this technique to even small changes in the chemical environment around the nuclei. This theoretical approach allows the exploration of all the different nuclei composing the material, thus providing a very useful guidance in the interpretation of experimental results, particularly valuable for the more challenging nuclei such as 43Ca and 17O.

Calcium orthophosphates (CaPO4): occurrence and properties

“…Computer simulations of the FA structure were performed as well (Li et al 2015 ). The detailed analysis of the electronic structure, bonding, charge transfer and optical properties of FA (Rulis et al 2004 ), as well as its NMR study under pressure (Pavan et al 2012 ) is available as well. In addition, there are reviews on FA solubility (Rakovan 2002 ) and the dissolution mechanism (Dorozhkin 2012e ).…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Computer simulations of the FA structure were performed as well (Li et al 2015). The detailed analysis of the electronic structure, bonding, charge transfer and optical properties of FA (Rulis et al 2004), as well as its NMR study under pressure (Pavan et al 2012) is available as well. In addition, there are reviews on FA solubility (Rakovan 2002) and the dissolution mechanism (Dorozhkin 2012e).…”

Computational NMR Spectroscopy of Ionic Liquids: [C4C1im]Cl/Water Mixtures

“…It is worth mentioning that computational NMR spectroscopy has been also successfully applied to solid-state NMR, for example to study polymorph structures or inorganic systems [13][14][15][16]. In such cases, chemical shift anisotropy information complement the set of NMR parameters that can be used for a comparison with experimental data [17][18][19].…”