Search

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]