Diffusion in amorphous LiNbO3 studied by Li-7 NMR comparison with the nano- and microcrystalline material

Lithium diffusion in amorphous LiNbO3, synthesized by a sol gel process, was investigated by temperature- and frequency-dependent Li-7 NMR experiments. Li-7 spin-lattice relaxation rates T-1(-1) and Li-7 nuclear magnetic resonance spectra, in particular line shapes and motional narrowing of the central line, were measured. The results are discussed in comparison with those on nano- and microcrystalline LiNbO3 investigated by us earlier. The Li diffusivity in the amorphous material is much higher than in the microcrystalline one and can be described by practically the same diffusion parameters as in nanocrystalline LiNbO3. This suggests that the diffusion pathways in amorphous LiNbO3 and in the interfacial regions of nanocrystalline LiNbO3 have similar structures.