Sol–gel derived Mn4+-activated magnesium fluorogermanate nanosized phosphors with deep-red emission properties

Abstract A series of (4− x )MgO· x MgF 2 ·GeO 2 :0.02Mn 4+ deep-red nanosized phosphors with orthorhombic symmetry was synthesized via a sol–gel process using CF 3 COOH as fluorine source. The microstructure, composition, morphology, and grain size of the samples, and the effect of synthesis conditions were investigated by powder X-ray diffractometry, X-ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry, and differential thermal analysis. The luminescence properties of (4− x )MgO· x MgF 2 ·GeO 2 :0.02Mn 4+ were discussed as a function of synthesis conditions. Under 280 nm light excitation, (4− x )MgO· x MgF 2 ·GeO 2 :0.02Mn 4+ shows two broad bands centered near 660 nm and 632 nm, which originate from the 2 E → 4 A 2 transition of the Mn 4+ ion and an anti-Stokes vibronic transition, respectively.