Achieving anti-thermal-quenching SrCa1-δMgW1-xO6:xMn, δLa3+phosphors by a nonequivalent substitution strategy

In this study, we report the successful synthesis of SrCa1-δMgW1-xO6:xMn, δLa3+ (SC1-δMW1-xO:xMn, δLa3+) phosphors using a nonequivalent substitution strategy from the nearly non-luminescent SCMWO:Mn. The as-synthesized (Mn, La3+) co-doped SCMWO phosphors exhibit highly efficient far-red luminescence, which is correlated with the valence transformation of Mn2+ to Mn4+ through La3+ substitution. Besides, the Mn2+ → Mn4+ valence transformation also results in a migration of Mn from the center of [MgO6] to [WO6]. More importantly, it was discovered that the SC0.81MW0.995O:0.005Mn, 0.19La3+ phosphor exhibited an excellent anti-thermal-quenching performance, with an emission intensity of 107.3 % at 423 K than that at 298 K. This phosphor also showed a high luminous efficiency, with an internal quantum efficiency (IQE) of 50.4 %, and an external quantum efficiency (EQE) of 43.2 %. Additionally, the intense far-red emission peak at 693 nm of SC0.81MW0.993O:0.007Mn, 0.19La3+ phosphor matches well with the absorption band of phytochrome PFR. These results indicate that the synthesized phosphors may have promising applications not only in plant growth but also in white light-emitting diodes (WLEDs).