Exploration of Mid-Temperature Alkali-Metal-Ion Extraction Route Using PTFE (AEP): Transformation of α-NaFeO2-Type Layered Oxides into Rutile-Type Binary Oxides

摘要

Alkali-metal-ion extraction reactions using poly-n(tetrafluoroethylene) (PTFE; AEP reactions) were performed onntwo ki n d s of α-NaFeO2 - t ype layered compounds:nNa0.68(Li0.68/3Ti1−0.68/3)O2 and K0.70(Li0.70/3Sn1−0.70/3)O2. At 400 °Cnin flowing argon, these layered compounds were reacted with PTFE.nBy these reactions, alkali-metal ions in the layered compounds werensuccessfully extracted, and TiO2 and SnO2 with rutile-type structurenwere formed. The structural similarity between the alkali-metal-ionextractednlayered compounds and the binary metal oxide products innthese unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomicnpair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ionsnfrom layered compounds, and AEP reaction is not limited to the previously reported γ-FeOOH-type layered titanianK0.8(Li0.27Ti1.73)O4, but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, itnwas clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult tonsynthesize by other reactions.