Self-diffusion in polycrystalline Li1+xTi2-xAlx(PO4)3 (0.2 = x = 0.4) samples followed by 7Li PFG (pulse field gradient) NMR spectroscopy

Short and long range lithium motions in powder Li1+xTi2-xAlx(PO4)3 (LTAP) NASICON compounds prepared by ceramic (x = 0.2 and 0.4) and sol-gel (x = 0.3 and 0.4) routes are discussed. ND diffraction and MAS-NMR spectroscopy were previously used to investigate structural features of these compounds. In particular, Fourier map differences showed that the amount of Li atoms allocated at M3 increases at the expense of M1 sites when the Li content increases. In this work, PFG-NMR results show that diffusion coefficients rise with the amount of lithium and temperature. The restricted diffusion inside NASICON particles is compared with “free” diffusion processes. At 300 K, diffusion coefficients DPFG