Ultraslow Li Exchange Processes in Diamagnetic Li₂ZrO₃ As Monitored by EXSY NMR

Two-dimensional (2D) 6 Li exchange magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy was used to probe extremely slow lithium hopping processes in a polycrystalline powder sample of lithium zirconate, Li 2 ZrO 3 . In agreement with the crystal structure of Li 2 ZrO 3, the 6 Li MAS NMR spectra recorded are composed of two signals (− 0.10 and 0.26 ppm) with equal intensity. They reflect the two magnetically (and electrically) inequivalent Li sites in Li 2 ZrO 3 . The mixing-time dependent 2D MAS NMR spectra, which were acquired at a bearing gas temperature of ca. 310 K, clearly reveal off-diagonal intensities indicating Li exchange processes with exchange rates as low as 60 jumps/hour. To our knowledge, this is by far one of the slowest Li solid-state diffusion processes ever probed by 6 Li 2D exchange MAS NMR spectroscopy (submitted to J. Phys. Chem. C, 2013 ).