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

Highlight
• (4−x)MgO·xMgF2·GeO2:0.02Mn4+ phosphors was synthesized by Sol–gel method.
• CF3COOH was used as fluorine source.
• We get nanosized phosphors with deep-red emission properties.
• The nanocrystals may be good candidates for near UV and blue LEDs.

A series of (4−x)MgO·xMgF2·GeO2:0.02Mn4+ deep-red nanosized phosphors with orthorhombic symmetry was synthesized via a sol–gel process using CF3COOH 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·xMgF2·GeO2:0.02Mn4+ were discussed as a function of synthesis conditions. Under 280 nm light excitation, (4−x)MgO·xMgF2·GeO2:0.02Mn4+ shows two broad bands centered near 660 nm and 632 nm, which originate from the 2E → 4A2 transition of the Mn4+ ion and an anti-Stokes vibronic transition, respectively.