Temperature-dependent photoluminescence properties of deep-red emitting Mn4+-activated magnesium fluorogermanate phosphors

Deep-red emitting Mn4+-activated magnesium fluorogermanate (MFG:Mn4+) phosphors have been synthesized by the solid-state reaction technique. Temperature-dependent photoluminescence properties of MFG:Mn4+ phosphors with various activator concentrations (0.001–0.015) were studied. The temperature dependence relation of the Mn4+ ions luminescence depends on activator concentrations, excitation wavelengths and emission bands that are measured. This luminescent temperature effect can be explained by the shifts of excitation spectra with temperature and the thermally activated concentration quenching. The MFG:Mn4+ phosphors can be effectively excited by near-UV or blue light and emit deep-red light, and simultaneously exhibit excellent resistibility against luminescent thermal quenching in the temperature range from 30 to 200 °C, which make them promising candidates of deep-red phosphors for white-LEDs applications.

► Various emission bands of Mn4+ ions show different temperature dependence relations.
► Activator concentrations and excitation wavelengths affect temperature dependent PL properties of MFG:Mn4+ phosphors.
► Luminescence of Mn4+ ions exhibit excellent resistibility against thermal quenching between 30 and 200 °C.
► MFG:Mn4+ phosphors can be used as deep-red phosphors for white-LEDs applications.