title: White luminescence of Dy3+ ions doped 12CaO 7Al2O3 nanopowders under UV light excitation.
abstract: 12CaO 7Al2O3:Dy3+ nanopowders were successfully synthesized by the chemical co-precipitation method. X-ray diffraction result shows that the single 12CaO 7Al2O3 phase is formed with Dy3+ ions to replace the Ca2+ ions in the host of 12CaO 7Al2O3. The yellow and blue emissions, attributed to the forced electric dipole transition of 4F(9/2) --> 6H(13/2) centered at 571 nm and the magnetic dipole transition of 4F(9/2) --> 6H(15/2) centered at 480 nm, respectively, were observed. The integrated intensity ratios of yellow to blue increase from 1.63 to 1.70 with Dy3+ concentration increasing from 0.8 to 2.0% for the as-prepared 12CaO 7Al2O3:xDy3+ phosphor. The significantly enhanced emission intensities of 12CaO 7Al2O3:1.0% Dy3+ phosphor annealed at 900 degrees C for 2 hours in vacuum ambient could be ascribed to the decrease of OH(-) groups and the change of the surface topography. The thermal stability and the Commission International de l'Eclairage coordinates were also investigated. All the photoluminescence characteristics indicate that Dy3+ ions doped 12CaO 7Al2O3 may be a good candidate for the solid state lighting phosphor as well as white light-emitting diodes.
authors.affiliation: Center for Advanced Opto-Electronic Functional Materials Research, School of Physics, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People's Republic of China.
authors.forename: Hancheng
authors.initials: H
authors.lastname: Zhu
authors.forename: Yuxue
authors.initials: Y
authors.lastname: Liu
authors.forename: Duanting
authors.initials: D
authors.lastname: Yan
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Yan
authors.forename: Chunguang
authors.initials: C
authors.lastname: Liu
authors.forename: Changshan
authors.initials: C
authors.lastname: Xu