Low-temperature solvothermal fluorination method and synthesis of La4Ni3O8Fx oxyfluorides via the La4Ni3O8 infinite-layer intermediate

A novel facile solvothermal fluorination method was developed for metastable oxyfluorides preparation by filling anion vacancies in parent structures. High solubility of XeF2 in acetonitrile and polarity of the solvent allowed for lower reaction temperature. The validity of the method was demonstrated by the preparation of a known oxyfluoride, SrCoO2.5F0.5, at unprecedented low temperature (100 ​°C). Additionally, two new oxyfluorides with idealized stoichiometry of La4Ni3O8F1 and La4Ni3O8F2, were prepared by the solvothermal fluorination via the La4Ni3O8 infinite-layer intermediate. The proposed method allows preparation of metastable oxyfluorides, utilizes only inexpensive commercial autoclaves and can potentially find widespread utilization in materials synthesis.