Microstructure and ion transport in Li1+x Ti2-x M x (PO4)3 (M = Cr, Fe, Al) NASICON-type materials

Li1 + x Ti2 - x M (x) (PO4)(3) (M = Cr, Fe, Al) NASICON-type materials have been prepared by the Pechini process and solid-state reactions and characterized by X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. We have identified the factors that determine the rate of ion transport in nanocrystalline and bulk samples at low and high temperatures. The effects of the preparation procedure and heterovalent doping on the ionic conductivity of the materials have been assessed. Heterovalent doping is shown to have a considerably stronger effect on the ionic conductivity in comparison with the microstructure of the materials.