KBr:Pr with a submicron rod structure is successfully synthesized by a solid-state reaction using absolute alcohol as the abrasive.X-ray diffraction,scanning electron microscopy,photoluminescence spectra and fluorescence decay curves are used to characterize the resulting materials.The influences of Pr^(3+)dopant concentration on the luminescence and lifetime are discussed.Furthermore,luminescent measurements show that KBr:Pr has a high emission intensity compared with other Pr-doped matrixes,which is related to the low phonon energy of KBr.The results suggest that the phonon energy of the host is important in determining the luminescent efficiency.
Er3+-doped 25BaO-(25-x)SiO2-xAl2O3-25B2O3 transparent glasses are prepared with x = 0,12.5 and 25 by a solid-state reaction.The Er-related NIR luminescence intensity,which corresponds to the transition of 4I15/2-4I13/2,is obviously altered with different silicon/aluminum ratios.The Judd-Ofelt parameters of the Er3+ ions are adopted to explain the intensity change in the NIR fluorescence,and the Raman scattering intensity versus the amount of Al and/or Si components are discussed.The spectra of the three samples are quite similar in the peak positions,but different in intensity.The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.
A series of aAl5O12:Ce (YAG:Ce) phosphors doped with different Si4+ concentrations is prepared by solid-state reaction. The temperature dependent characteristics of luminescent spectrum and decay time of Ce3+ are investigated. With Si4+ doped, the emission spectrum shows a blue shift clue to a decrease of the splitting of 5d levels of Ce3+ ion. The thermal stability is greatly improved by adding Si4+ because the activation energy AE increases from 0.1836 eV to 0.2401 eV. The study of the decay times against temperature for various doping concentrations of Si4+ shows that the calculated nonradiative decay rate is affected by Si4+ substitution. The results are explained by the configurational coordinate diagram.