Complete, reversible H/Li ion exchange reaction between rhombohedral LiMO3 and perovskite-type HMO3 (M=Nb, Ta)

We demonstrate for the first time the complete, reversible H⁺/Li⁺ ion exchange reaction between HMO₃ and LiMO₃ (M=Nb, Ta) using molten LiNO₃ at 320°C for 5 days. HMO₃ were prepared from LiMO₃ by ion exchange reactions using dilute HNO₃. The results reveal that both LiMO₃ prepared by normal solid state reaction between Li₂CO₃ and M₂O₅, and by ion exchanged from HMO₃ using molten LiNO₃ are isostructural. LiMO₃ prepared using HMO₃ yields nearly uniformly sized crystallites in contrast to those prepared by conventional solid state synthesis. The present method is simple and inexpensive compared to other methods of preparation of high purity LiMO₃ powders.