Luminescent properties of Eu-doped magnetic NaFeF.

Sodium iron fluoride (NaFeF) is a colorless ferromagnetic fluoride with a monoclinic crystal structure (space group 21/), and it is expected to be an ideal platform for exploring magneto-optical interactions. In the present work, Eu doped NaFeF micro-powders were synthesized by a hydrothermal method, and the structures were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties were examined using UV-Vis spectra and fluorescence spectra, and the results show that the emission spectra can be finely tuned by the hydrothermal reaction temperature and doping concentration of Eu ions. We found that NaFeF doped with 5% Eu synthesized at 196 °C exhibited the optimal red emission under excitation at 395 nm. The magnetization of NaFeF:5% Eu decreased rapidly from about 7.85 emu g at 5 K to 0.4 emu g at 60 K, then slowly decreased with temperature increase from 60 K to 300 K. This Eu doped NaFeF powder is expected to find potential applications in the field of magneto-optical modulation and relevant devices.