Single-crystal structure refinement and luminescence analysis of β-NaEuF₄

The crystal structure of β-NaEuF₄ has been refined from single-crystal diffraction data. The obtained results confirm the previous description in the hexagonal P6-C¹_3h space group reported by Burns. Three Eu³⁺ centres could have been identified analysing the luminescence spectra of the titled compound. Two of them are related to the current C_3h sites. The third one which exhibits the most intense luminescence corresponds to the 2h cationic site (Na⁺) (half occupied in the structure) partially substituted by Eu³⁺. Occurrence of this third Eu³⁺ site obscures the features due to the other sites in luminescence spectra and explains the disagreement already noted between the optical study results and the crystallographic data for NaYF₄:Eu³⁺.