Novel Solid State NMR Approaches for the Structural characterization of Rare Earth Nuclei in Intermetallic Compounds: The Nuclei 139La and 175Lu
Solid-state NMR spectroscopy has been shown to be a very powerful probe for structural investigations of intermetallic compounds. Nevertheless, studies on intermetallic compound containing rare-earth metals are strongly restricted by to their paramagnetic character, limiting standard magic angle spinning (MAS)-NMR to work on the nuclei of closed-shell ions Sc3+, Y3+, La3+, and Lu3+. For the latter two species, an additional limitation arises from the nuclear electric quadrupolar interaction of the 139La and 175Lu nuclei, producing excessive line-broadening effects. Previous work that has shown that signals are easily detected in compounds of high symmetry and low defect concentrations. The goal of my project is to overcome the these limitations for crystalline and amorphous materials featuring the rare-earth ions in lower symmetries. To this end we are using wideband uniform-rate smooth truncation (WURST) spectroscopy together with field-dependent lineshape analyes of static and MAS-NMR spectra. In addition internuclear magnetic dipole-diple interactions are being characterized spin-spin relaxation time measurements via static spin echo decay spectroscopy and rotational echo double resonance (REDOR). We expect that the results acquired from the approach presented here will expand the applicability of solid-state NMR for studying materials for frontier challenges in materials chemistry associated with several areas of application.