Lithium transition metal (Ti, Nb, V) oxide mesoporous thin films: Contrasting results when attempting direct synthesis by evaporation-induced self assembly
التفاصيل البيبلوغرافية
العنوان:
Lithium transition metal (Ti, Nb, V) oxide mesoporous thin films: Contrasting results when attempting direct synthesis by evaporation-induced self assembly
This work investigates the possibility to prepare mesoporous thin films of Li–Ti, Li–Nb, Li–Nb–V and Li–V oxides through a direct sol–gel EISA route by dissolving a lithium salt in the precursor solution. Experimental conditions involve a hydrolysis molar ratio H 2 O/TM ∼ 10 (TM = Ti, Nb, V) and the common Pluronic structuring agent P123 (EO 20 –PO 70 –EO 20 ). Systematic formation of lithium-containing oxides as first-crystallizing phases points to a significant intermixture of lithium and transition metal ions in the inorganic network. In the case of Ti-based and Nb-based oxide films, addition of lithium to the precursor solution is compatible with the formation of amorphous mesoporous films at 350 °C. On the contrary, addition of lithium has a detrimental effect on the notoriously difficult formation of vanadium-based mesostructured films: even when replacing half of the vanadium by niobium as a stabilizer, formation of mesostructured films has not been possible in the investigated range of experimental conditions.