Synthesis and luminescence characteristics of novel red-emitting Ba2TiGe2O8:Mn4+ phosphor

Novel Ba2TiGe2O8:Mn4+ red-emitting phosphor is synthesied by high-temperature solid-state reaction method in air. The excitation spectrum including two peaks at 300 nm and 435 nm covers a broad spectral region from 220 nm to 500 nm owing to the Mn4+ -O2- charge transfer band and the (4)A(2) -> T-4(1) and T-4(2) transitions of Mn4+ ion. Emission band peaking at-666 nm in the range of 600-750 nm can be observed due to the transition E-2 -> (4)A(2) of Mn4+ ion with the lattice vibrations. The luminescence properties indicate that Ba2TiGe2O8:Mn4+ phosphor has a potential application for plant cultivation. The quantum.efficiency is similar to 35.6%. The optimal Mn4+ doping concentration is similar to 0.6 mol%. The decay curve and time-resolved spectra confirm that there is only a single Mn4+ ion luminescence center in Ba2TiGe2O8:Mn4+ phosphor. Temperature dependence of emission indicates that Ba2TiGe2O8:Mn4+ phosphor has a good thermal stability. Luminous mechanism is explained by Tanabe-Sugano energy level diagram of Mn4+ ion. (C) 2017 Elsevier Ltd. All rights reserved.