The characterization and mechanism of energy transfer in Na2Mg(SO4)2: Ce phosphor co-doped by Dy, Mn and Tb

The phase formation of the compound Na2Mg(SO4)2 prepared by a wet chemical method was confirmed by the X-ray powder diffraction (XRD) pattern. Photoluminescence (PL) of Na2Mg(SO4)2: Ce3+ shows strong emission at 322 nm, and this phosphor is also efficient for Ce3+→ Dy3+ and Ce3+→ Mn2+ energy transfers. The Dy3+ emission by Ce3+→ Dy3+ under UV wavelength is peaking at 475 nm and 572 nm for an excitation of 254 nm due to 4F9/2 →6H15/2 and 6H13/2 transitions, whereas Ce3+→Mn2+ is peaking at 515 nm due to 4T1→6A1 transitions. The Tb3+ emission by Ce3+→Tb3+ under UV wavelength is peaking at 490, 529, 546 nm, (with a small peak at 586 nm) for the excitation of 352 nm due to 5D4→7FJ (J=4, 5, 6) transitions. The purpose of the present study is to develop and understand the photoluminescence and effect of Dy3+, Mn2+ or Tb3+ co-doping in Na2Mg(SO4)2:Ce3+ new luminescent materials, which can be the green phosphor in many applications such as lamp phosphors.