Pavels Rodionovs

Mn2+ transition metal ion activator has attracted considerable attention as an cost-effective alternative to rare-earth ions.Stabilizing Mn2+ in oxide lattices synthesized under oxidative conditions remains challenging due to unwanted oxidation of manganese into Mn3+/Mn4+. In this work, Ti4+ aliovalent co-doping strategy was employed to regulate the oxidation state of Mn in CaAl12O19 prepared in air. CaAl12O19 doped with manganese exhibits green Mn2+ emission at 518 nm and red Mn4+ emission at 656 nm. CaAl12O19:Mn phosphor was co-doped with varying amounts of Ti4+. The coupled substitution of Mn2+ and Ti4+ effectively suppresses the formation of Mn3+ and Mn4+ and promotes the formation of Mn2+ centers. Enhanced luminescence is primarily attributed to the reduction of non-radiative energy transfer from Mn2+ to Mn3+/Mn4+. An optimized composition CaAl12O19:0.04Mn; 0.1Ti demonstrated a 40-fold increase in Mn2+ luminescence intensity and a maximum absolute photoluminescence quantum yield of 64%.

This paper reports on Sr ₂ MgSi ₂ O ₇ :Pr ³⁺ phosphors that simultaneously exhibit upconversion emission in the ultraviolet range (235–300 nm) and photoluminescence in the visible and near-infrared regions under excitation at 444 nm.

Illustration of dynamic multicolor anticounterfeiting application of MGGO:Mn²⁺ materials (Mn²⁺ content 0.005–0.5).

Currently, extensive research activities are devoted to developing persistent phosphors which extend beyond the visible range. In some emerging applications, long-lasting emission of high-energy photons is required; however, suitable materials for the shortwave ultraviolet (UV–C) band are extremely limited. This study reports a novel Sr₂MgSi₂O₇ phosphor doped with Pr³⁺ ions, which exhibits UV–C persistent luminescence with maximum intensity at 243 nm. The solubility of Pr³⁺ in the matrix is analysed by X-ray diffraction (XRD) and optimal activator concentration is determined. Optical and structural properties are characterised by photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) spectroscopy techniques. The obtained results expand the class of UV–C persistent phosphors and provide novel insights into the mechanisms of persistent luminescence.