Synthesis, crystal structure, and the ionic conductivity of new lithium ion conductors, M-doped LiScO2 (M= Zr, Nb, Ta)

Abstract

New lithium ion conductors of M-doped LiScO2 (M = Zr, Nb, and Ta) were synthesized by a solid-state reaction method. Peak shifts of the X-ray diffraction patterns revealed the formation of solid solutions with aliovalent cation doping. In addition, increase in the ionic conductivity by M doping is indicated. The highest total conductivity of 7.94 × 10-6 S cm-1 at 623 K with an activation energy of 88 ± 5 kJ mol-1 was observed for the Zr 4+ doped sample in the systems. The Zr 4+ doped system showed the largest solid solution limit in Li1-xSc 1-x ZrxO2 (x ≈ 0.1) and continuous increase of the conductivity with increasing x. Structural analysis by Rietveld refinement indicated that the lattice expansion and lithium-ion vacancy formation by the Zr doping in the structure, which could contribute to the increase in the ionic conductivity.