Al-27 NMR Chemical Shifts in Oxide Crystals: A First-Principles Study

作者：Choi Minseok^*; Matsunaga Katsuyuki; Oba Fumiyasu; Tanakat Isao

来源：Journal of Physical Chemistry C, 2009, 113(9): 3869-3873.

DOI：10.1021/jp810484j

In the framework of density functional theory using periodic boundary conditions, Al-27 nuclear magnetic resonance (NMR) parameters of 20 aluminum sites in 12 aluminum-containing crystalline oxides, i.e., Al2O3, LiAlO2, SiAl2O5, MgAl2O4, YAlO3, AlVO4, and their polymorphs, are investigated. The present method excellently reproduces the Al-27 NMR parameters and the well-known empirical correlation of the isotropic chemical shifts, delta(iso) of Al-27 nuclei with its number of coordinating oxygen atoms, i.e., coordination number. Through systematic calculations, we demonstrate that the mean Al-O bond order, Q(Al-O), can be a better parameter to correlate with Al-27 delta(iso) than merely averaged bond length or the coordination number. The relationship between delta(iso) and Q(Al-O) is also found to be valid for alpha-Al2O3 under hydrostatic pressures in which the coordination number is unchanged from six.

• 出版日期2009-3-5