Mixed ion effect in Li/Na–NaZr2(PO4)3

The mixed ion effect (MIE) in Li/Na–NaZr2(PO4)3 with a three-dimensional diffusion path was observed. The conductivity minimum at an ionic ratio 0.8 was lower by about three orders of magnitude than for either end member. Hexagonal parameters a, c and 7Li MAS/NMR spectral intensity against the ionic ratio showed a linear change. The spectral width of 31P MAS NMR at chemical shift 5.9 ppm against the ionic ratio showed a minimum at the same ionic ratio with the conductivity data. The behavior suggests that the conductivity minimum results from the inhomogeneous distribution of two unlike ions and a blocking of diffusion path.