On cationic mobility in Nasicon phosphates LiTi2(PO4)3 and Li0.9Ti1.9Nb0.1(PO4)3

A systematic examination of LiTi2(PO4)3 and Li0.9Ti1.9Nb0.1(PO4)3 phosphates with Nasicon structure was carried out in order to investigate “order–disorder” phase transitions. The structural features of aliovalent doped Li0.9Ti1.9Nb0.1(PO4)3 are considered in comparison with initial LiTi2(PO4)3. Explanations of the thermal behavior of samples are proposed based on NMR 7Li, 93Nb data, X-ray powder diffraction, DSC and impedance spectroscopy.

► We examine Nasicon-related phosphates with lithium mobility.
► Nb5+ doping of LiTi2(PO4)3 decreases conductivity by lithium channels blocking.
► Order-disorder transition is observed without changing of space group.
► We conclude such transition is due to “defrosting” of lithium sub-lattice.