The electrical properties and crystal structures of ceramic electrolytes which were based upon this material were investigated. The conductivity increased with increasing amount of Li2O, and with additions of Cr, Fe, Sc, In, Lu or Y. The P21/n monoclinic phase transformed to a NASICON-type R¯3c rhombohedral phase at temperatures above 1173K. The activation energy for Li+ ion migration was decreased by the phase transition. The activation energy for the bulk component was 0.42eV in the NASICON-type structure. The maximum conductivity at 298K was 0.00017S/cm, for a sample of Li1.2Fe0.2Hf1.8(PO4)3.

H.Aono, E.Sugimoto, Y.Sadaoka, N.Imanaka, G.Adachi: Solid State Ionics, 1993, 62[3-4], 309-16