The conductivity and structure of crystalline or glassy Na4NbP3O12 were studied. Alternating-current impedance and FTIR data indicated the presence of pyrophosphate (P2O74-) groups in both crystalline and glassy samples. The ionic conductivity of the glass (0.0031S/cm at 400C) was at least 2 orders of magnitude higher than that of the crystalline phase (3.0 x 10-5S/cm). This was attributed to large differences in the structures of the 2 modifications and to the random distribution of Na+ ions over equipotential sites in the glass network.

B.Wang, M.Greenblatt, J.Yan: Solid State Ionics, 1994, 69[1], 85-9