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The variations of luminescence properties of silicate Ba (1− x ) MgSiO 4 : x Eu phosphors are investigated in view of the structure of the host matrix and different synthetic atmosphere. X-ray powder diffraction patterns, luminescent spectra and electron spin resonance are used to confirm the compound structure and detected the simultaneous existence of both divalent and trivalent europium ions. The results indicate that both Eu 2+ and Eu 3+ are co-existing in the silicate when synthesized under air atmosphere due to the substitution of Eu 3+ cations for alkaline earth (Ba 2+ ) triggers the formation of V B a / / vacancies that play the role of electron donor towards E u B a defects. The higher the concentration of V B a / / , the easier the reduction of Eu 3+ into Eu 2+ . The co-doping with higher state chemical elements ( i . e ., La 3+ , Zr 4+ ) helps a lot in increasing the concentration of Eu 2+ cations at the expense of Eu 3+ ions in the Ba (1− x ) MgSiO 4 : x Eu phosphors. The energy transfer between Eu 2+ cations in different sites within the BaMgSiO 4 host matrix is also observed and its mechanism is charged by multipolar interaction. [ABSTRACT FROM AUTHOR]

Either quantum-cutting luminescence (QCL) or long-persistent luminescence (LPL) phosphor has been attracted attention for practical applications. Due to the real-time excitation source (low efficiency) for the QCL (LPL) process, both QCL and LPL have their own shortcomings. By combining the inherent properties of QCL and LPL, we devise a concept of QCLPL (quantum cutting long persistent luminescence), which can obtain high efficient LPL (at least > 100%). Germinate Ca 3 Ga 2 Ge 3 O 12 (CGG) is chosen as matrix due to its low phonon frequency. Pr 3+ is selected as donor (D) ion owing to its ladder-like arranged energy levels which facilitate the photon absorption and subsequent energy transfer (ET). Yb 3+ ion is codoped as acceptor (A) ion due to its absorption and emission in near-infrared (NIR) region. Since the “optical transmission window” of biological tissues within 700–1100 nm allows for deeper light penetration, the QCLPL CGG: Pr 3+ , Yb 3+ (CGGPY) results in increasing bioimage contrast. Meanwhile, as a down-conversion luminescent medium, CGGPY transfers UV light to NIR light, which increases the solar light harvest and photocurrent of dye-sensitized solar cells (DSSCs). Altogether, the strategy of combination of QCL and LPL processes in one host lattice has important implications for infrared lighting, DSSCs, bioimaging and et al. [ABSTRACT FROM AUTHOR]