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Broadband near-infrared (NIR) phosphors have received increasing attention for fabricating NIR light sources. In this article, based on our predictions of heavy Mn-doped models obtained using DFT calculations, we successfully synthesize and characterize manganese-based magnetoplumbite-type La(Zn,Mn)Al11O19 phosphors, which crystallize into a hexagonal structure with space-group P63/mmc. Under excitation at 450 nm, it was found that LaZn0.7Mn0.3Al11O19 and LaZn0.2Mn0.8Al11O19 had the optimal emission intensity and the maximum quantum efficiencies were 99% and 55%, respectively. An anomalous near-infrared (NIR) emission band at ∼730 nm is observed for the LaZnAl11O19 host with heavy Mn2+ doping. The density functional theory calculations and transient and steady-state luminescence investigation suggest that this unusual NIR emission band comes from the Mn2+–Mn2+ dimers. Moreover, the as-prepared phosphor, being integrated into high-powered photonic devices, could operate at high temperature without degeneration, due to the great advantage of the phosphor-in-glass (PiG) approach. Consequently, our study not only develops a viable strategy for synthesising innovative NIR phosphors, but also sheds light on the development of high-power photonic devices and procedures. [ABSTRACT FROM AUTHOR]

Developing chemically and thermally stable, highly efficient green-emitting inorganic phosphors is a significant research field in solid-state lighting. In this work, we successfully tailor the properties of an yttrium silicate based Na3(Y,Sc)Si3O9:Eu2+ phosphor as a highly efficient green phosphor via crystal field engineering. The quantum efficiency (QE) and thermal stability of Na3(Y,Sc)Si3O9:Eu2+ were increased by 33% and 35%, respectively, via the combination of structure and bandgap engineering. Meanwhile, persistent luminescence (PersL) was observed, followed by a more thorough investigation of the relationship between the intensity of afterglow and Sc3+ concentration. Accordingly, the excitation temperature-dependent and fading thermoluminescence experiments are conducted, and the trap properties are deeply studied by the initial rising method. The results reveal the PersL mechanism and the significant role of Sc3+ as substitute ions. These results clearly indicate that our proposed designing concept of PersL materials are indeed effective and feasible, and the as-prepared Na3Y0.5Sc0.5Si3O9:Eu2+ phosphors are certainly promising for multifunctional applications. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics are a highly attractive class of materials for photonic applications. Transition metal ions are promising candidates for luminescence centers thanks to the sensitivity of the ligand ions to d–d electron transition. Here, broadband second near-infrared (NIR-II) photoluminescence was achieved via precipitation of ZnGa2O4:Ni2+ nanocrystals within a zinc gallium–silicate glass matrix by a crystallization process. Excited by 260 nm UV photons, ZnGa2O4:Ni2+ GC displays NIR-II emission peaking at 1240 nm and has a full width at half maximum wider than 288 nm, attributed to 3T2g(3F) → 3A2g(3F) electronic transition of octahedrally coordinated Ni2+ ions. Moreover, broad persistent luminescence of Ni2+ ions can be effectively obtained after irradiation in UV light. Based on the electron paramagnetic resonance spectra and a thermoluminescence method, a physical model was constructed to demonstrate the mechanism of persistent luminescence. This developed afterglow luminescent glass-ceramic exhibits potential applications in biological imaging. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics are a highly attractive class of materials for photonic applications. Transition metal ions are promising candidates for luminescence centers thanks to the sensitivity of the ligand ions to d–d electron transition. Here, broadband second near-infrared (NIR-II) photoluminescence was achieved via precipitation of ZnGa2O4:Ni2+ nanocrystals within a zinc gallium–silicate glass matrix by a crystallization process. Excited by 260 nm UV photons, ZnGa2O4:Ni2+ GC displays NIR-II emission peaking at 1240 nm and has a full width at half maximum wider than 288 nm, attributed to 3T2g(3F) → 3A2g(3F) electronic transition of octahedrally coordinated Ni2+ ions. Moreover, broad persistent luminescence of Ni2+ ions can be effectively obtained after irradiation in UV light. Based on the electron paramagnetic resonance spectra and a thermoluminescence method, a physical model was constructed to demonstrate the mechanism of persistent luminescence. This developed afterglow luminescent glass-ceramic exhibits potential applications in biological imaging. [ABSTRACT FROM AUTHOR]

By introducing halogens to the A/Ga/Q (A = Na, K; Q = S, Se) system, one new chalcohalide namely Na2GaS2Cl was successfully obtained. It crystallizes in the orthorhombic space group Cmcm (63). Na2GaS2Cl has a layered structure consisting of two dimensional [GaS2]∞ layers which are stacked in "face to face" and "back to back" arrays and separated by Na+ and Cl− ions. Interestingly, supertetrahedral building units [Ga4S10] (T2) which are rarely found in metal chalcogenides and metal chalcohalides are formed in this structure. Moreover, the distances of two adjacent layers are around four times larger than the ionic radius of the Na+ ion, which is very likely to provide a perfect environment for the storage and migration of Na+ ions. In particular, the volume concentration of the Na+ cations in this compound is as high as 1.54 × 1022 cm−3. The UV-vis-NIR spectroscopy measurement reveals that the optical band gap of this title compound is 3.06 eV. The electronic structural calculations on Na2GaS2Cl show that the band gap is mainly determined by the [GaS4] groups and Na–Cl ionic bonding. [ABSTRACT FROM AUTHOR]

By introducing halogens to the A/Ga/Q (A = Na, K; Q = S, Se) system, one new chalcohalide namely Na 2 GaS 2 Cl was successfully obtained. It crystallizes in the orthorhombic space group Cmcm (63). Na 2 GaS 2 Cl has a layered structure consisting of two dimensional [GaS 2 ] ∞ layers which are stacked in "face to face" and "back to back" arrays and separated by Na + and Cl - ions. Interestingly, supertetrahedral building units [Ga 4 S 10 ] (T2) which are rarely found in metal chalcogenides and metal chalcohalides are formed in this structure. Moreover, the distances of two adjacent layers are around four times larger than the ionic radius of the Na + ion, which is very likely to provide a perfect environment for the storage and migration of Na + ions. In particular, the volume concentration of the Na + cations in this compound is as high as 1.54 × 10 22 cm -3 . The UV-vis-NIR spectroscopy measurement reveals that the optical band gap of this title compound is 3.06 eV. The electronic structural calculations on Na 2 GaS 2 Cl show that the band gap is mainly determined by the [GaS 4 ] groups and Na-Cl ionic bonding.