Conductivity measurements were carried out on the solid solutions, Na3Zr2-x/4Si2-xP1+xO12, for x-values of between 0 and 2. The materials were Zr-deficient Nasicon. A monoclinic to rhombohedral phase transition occurred at an x-value of about 0.333. The variation in the ionic conductivity as a function of x was investigated at temperatures ranging from 150 to 600K. It was shown that the bulk ionic conductivity decreased slightly, from 6 x 10-4S/cm for the Zr non-deficient Nasicon (x = 0), to 6 x 10-5S/cm for the most Zr-deficient material (x = 1.667). The structural change did not affect the ionic conductivity. The mobility of Na+ ions in these materials seemed to be affected mainly by the size of the bottlenecks through which the ions had to pass. Variations in the ionic conductivity and in the activation energy for ionic motion were explained in terms of the structure.

Conductivity Measurements of Nasicon and Nasicon-Modified Materials. O.Bohnke, S.Ronchetti, D.Mazza: Solid State Ionics, 1999, 122[1-4], 127-36