Structural studies of LiScP2O7, using Rietveld refinement, confirmed that this material was iso-structural with LiFeP2O7. However, the NaScP2O7 had a structure which was different to the known structural types of the basic NaMIIIP2O7 group. Systematic ranges of the 6 structural types of the latter group were presented in terms of ion-radii sums and ratios. It was found that the framework of LiMP2O7, where M was Sc or Fe, had rather wide tunnels running along the crystallographic c-axis. This prompted interest in the ion conductivity of AIMIIIP2O7, where A was Li or Na and M was Sc or Fe. However, the bulk conductivity was low in these compounds, being of the order of 10-6 to 10-7S/cm at 300C; as determined by impedance spectroscopy. Heterovalent substitution was used in order to facilitate conductivity via normal Li sites.

Structural and Conductivity Studies in LiFeP2O7, LiScP2O7 and NaScP2O7. G.Vitins, Z.Kanepe, A.Vitins, J.Ronis, A.Dindune, A.Lusis: Journal of Solid State Electrochemistry, 2000, 4[3], 146-52