Synthesis and photoluminescence spectroscopy of BaGeF6:Mn4+ red phosphor

We synthesized Mn4+-activated BaGeF6 red phosphor by the chemical reaction method from HF, H2SiF6, BaF2, KMnO4, and GeO2 powder. The structural and optical properties of BaGeF6:Mn4+ were investigated using X-ray diffraction analysis, secondary electron microscopy observation, electron spin resonance measurement, photoluminescence (PL), PL excitation (PLE) and Raman scattering spectroscopies, and luminescence decay time measurement. Temperature dependence of the PL intensity was measured from T = 20 to 500 K and analyzed by taking into consideration the Bose–Einstein phonon occupation number. The PLE spectra measured at T = 20 and 300 K and luminescence decay time at T = 20–460 K were also analyzed based on the Franck–Condon and conventional thermal quenching models, respectively. Comprehensive discussion was given on the Mn4+-related PL properties and Raman scattering behaviors in a family of the barium hexafluorometallate phosphors.