Search

SrIn2O4, which shows lower phonon energy than CaIn2O4, is not only a good photocatalyst but also can be an excellent up-conversion (UC) host to exhibits UC luminescence. In this work, Yb3+ and/or Er3+ doped SrIn2O4 phosphors were synthesized, and their UC luminescence properties were studied and compared with those in the CaIn2O4 host. The structure of SrIn2O4: 0.01Er3+ and SrIn2O4: 0.1Yb3+/0.01Er3+ samples were refined by the Rietveld method and found to that SrIn2O4: 0.1Yb3+/0.01Er3+ showed increasing unit cell parameters and cell volume, indicating In3+ sites were substituted successfully by Yb3+ and/or Er3+ ions. From the UC luminescence spectra and diffuse reflection spectra, Er3+-doped SrIn2O4 showed very weak luminescence due to ground state absorption of Er3+; Yb3+/Er3+ codoped SrIn2O4 presented strong green (550 nm) and red (663 nm) UC emissions which were assigned to energy transfer from Yb3+ transition 2F7/2→2F5/2 to the Er3+ transition 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2. Comparing with CaIn2O4, Yb3+/Er3+ codoped SrIn2O4 showed obvious advantages with higher UC luminescent intensity. The pumping powers study showed that UC emissions in Yb3+/Er3+ codoped SrIn2O4 were attributed to energy transfer of Yb3+→Er3+ with a two-photon process. The possible UC luminescent mechanism of Yb3+/Er3+-doped SrIn2O4 was discussed. [ABSTRACT FROM AUTHOR]

Novel LaMgAl11O19:Tm3+, Dy3+ phosphors were prepared utilizing a high-temperature solid-state reaction method. The phase formation, luminescence properties, energy-transfer mechanism from the Tm3+ to the Dy3+ ions, the thermal stability, and CIE coordinates were investigated. When excited at 359 nm, the LaMgAl11O19: xTm3+ phosphors exhibit strong blue emission bands at 455 nm. After codoping with Dy3+ and excitation at 359 nm, the LaMgAl11O19:0.03Tm3+, yDy3+ phosphors emitted white light consisting of the characteristic emission peaks of Tm3+ and Dy3+. The Dy3+ emission intensity increased with the Dy3+ concentration due to the energy transfer from Tm3+ to Dy3+, and concentration quenching due to the high Dy3+ doping concentration (y = 0.1 mol) did not occur. The calculation of the CIE coordinates of the LaMgAl11O19: Tm3+, yDy3+ phosphors revealed the tunability of the emission color from blue to bluish-white and to white by changing the excitation wavelength and the doping concentration. An energy transfer from Tm3+ to Dy3+ by dipole-dipole interaction was confirmed by the decay curve, lifetime, and energy-transfer efficiency measurements. When excited at 359 nm, the LaMgAl11O19:Tm3+, Dy3+ phosphor also showed good thermal stability, suggesting that it can be used in white LEDs excited by a GaN-based ultraviolet LED. [ABSTRACT FROM AUTHOR]