Solid state 27Al NMR investigation of Knight shift tensors of LnAl2 (Ln=Y, La and Lu) and correlation with DFT calculations

Abstract

The atomic and electronic structures of LnAl2 (Ln=Y, La and Lu) on Al sites were characterized by 27Al solid state NMR spectroscopy. 27Al isotropic metallic shifts have been determined in these cubic laves phases under both static and magic angle spinning (MAS) conditions. Based on band structure calculations, we found a strong correlation of 27Al isotropic metallic shifts and s character of the density of states at the Fermi level on Al sites. We also found tetrahedral distortion of Al centered clusters, which can be well characterized by quadruple coupling constants and Knight shift anisotropy.