Synthesis of nanostructured Li3Me2(PO4)2F3 glass-ceramics (Me = V, Fe, Ti)

The aim of this research was to synthesize high-conducting nanostructured fluorophosphate materials starting from LiF-Me2O3-P2O5 (Me = V, Fe, Ti) glasses, whose nominal composition was close to that of the polycrystalline Li3Me2(PO4)2F3. All the compositions under study which contained up to 0.5 Fe per nominal formula were synthesized initially in amorphous state. Their thermal treatment led to significant changes in their electric conductivity. The best conducting sample (σ(25 °C) = 1.7 × 10− 3 S/cm) was the one of composition Li3V2(PO4)2F3 after nanocrystallization at 500 °C. The average crystallite size was 75 nm. Two factors are the most important for the efficiency of the electrical conductivity of the nanostructured materials under consideration: a high concentration and a short average distance between hopping centers (i.e. aliovalent V, Fe or Ti ions).