Yan Cong

Synthesis and Luminescence Properties of Cube-Structured CaSnO3 ∕ RE3 + ( RE = Pr , Tb ) Long-Lasting Phosphors

Uniform and cube-structured RE 3+ (RE = Pr,Tb)-doped CaSnO 3 phosphors have been successfully synthesized by a two-step approach including the room-temperature synthesis of CaSn(OH) 6 precursors with the help of cetyltrimethylammoniumbromide surfactant and then converted to CaSnO 3 by calcination at 750°C. The decomposition process of the Casn(OH) 6 precursor, crystallization, and morphology of the as-synthesized CaSnO 3 phosphors have been investigated using thermal analysis, X-ray diffraction, and scanning electron microscopy. Furthermore, luminescence properties of CaSnO 3 /RE 3+ (RE = Pr,Tb) phosphors, including photoluminescence, fluorescence lifetime, afterglow decay, and thermoluminescence, are also systematically discussed in this paper. The as-synthesized Pr 3+ and Tb 3+ doped CaSnO 3 phosphors show intense luminescence under ultraviolet excitation. Moreover, the afterglow emission from CaSnO 3 /RE 3+ (RE = Pr,Tb) phosphors lasts for more than 3 h after the ultraviolet irradiation source has been removed. Both the fluorescence and afterglow decay curves of the CaSnO 3 /RE 3+ (RE = Pr,Tb) phosphors contain one fast decay component and another slow decay process. Thermoluminescence spectra indicate that the incorporation of RE 3+ ions into the CaSnO 3 host produces suitable trapping centers, which are the origin of the long-lasting phosphorescence phenomenon in this kind of material at room temperature.

Synthesis and Optical Property Studies of Nanocrystalline ZrO2 : Ti Long-Lasting Phosphors

A facile synthetic route to synthesize the nanocrystalline zirconia particles via preparing polyzirconoxane with zirconium tetraalkoxide is reported, and the luminescent properties of the so-obtained ZrO 2 :Ti nanophosphors are systematically investigated in this paper. The bluish-white photoluminescence and phosphorescence originating from the recombination of electrons trapped by anion vacancies and the holes created in the valence band, and the Ti 3+ ion substituting for Zr 4+ is assumed to be the luminescent center. The long afterglow from ZrO 2 :Ti is attributed to the oxygen vacancies caused by the addition of Ti 3+ ions into ZrO 2 host. Compared with the bulk ZrO 2 :Ti, the nanosized phosphors exhibit a longer persistent time because of the increased surface traps due to the large surface-to-volume ratio in the nanoparticles. This long persistent process can be elucidated by a simple possible mechanism.

Enhanced Red Phosphorescence in MgGeO3 : Mn2 + by Addition of Yb3 + Ions

Enhancement of the 4 T 1g ( 4 G) → 6 A 1g ( 6 S) red emission of MgGeO 3 :1% Mn 2+ with addition of Yb 2 O 3 is reported. The initial phosphorescence in the Yb 2 O 3 codoped sample is an order of magnitude stronger than that of the Yb 2 O 3 -free sample. Thermoluminescence spectra indicate that the introduction of Yb 3+ into the host produces traps with a suitable depth, resulting in the enhanced red phosphorescence of Mn 2+ . The possible mechanism for this phenomenon is explained by a competitive trapping model.