A wide range of solid solution formation in the Li&e04-LizZnCe04-LisPOg system was observed to occur with a structure based on rII_LisPOd.This includes the fast Li conductor lisicon (Li14Zn(Ge04)4).The ionic conductivities of solid solutions in this system are reported. Much of the solid solution range is structually metastable at room temperature; however, the decomposition kinetics are appreciable only at elevated temperatures (> 35O'C). The evolution of low Li&e04 on decomposing causes an irreversible decrease in the conductivity. At 2OO"C, the bulk ionic conductivity of several of these solid solutions is higher than that of lisicon. Solid solutions along the Li&e04-Li3P04 tie line are structurally stable and have a higher bulk ionic conductivity than lisicon, and also of the corresponding Li&iO4-Li3PO4 solid solutions at 200°C.

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The infrared and Raman spectra of LaAlTeOe, LaGaTeO6, In2TeO6 and Y2TeO6 are reported. Structure proposals are confirmed and the space group of Y2TeO6 determined. A relation between spectral position of vibrational modes and quenching temperature of luminescence is outlined.