Papers by Keyword: Dy³⁺

Abstract: SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors were synthesized under different temperature by high temperature solid phase method. Encapsulation modification of SrAl₂O₄:Eu²⁺,Dy³⁺ by using SiO₂ glycol were made over chemically unstable against water. Photoluminescence measurement result shows that when the sintering temperature is 1300 °C, the initial afterglow brightness of SrAl₂O₄:Eu²⁺,Dy³⁺ is up to the highest, 12101 mcd/m². FTIR results showed that new IR peaks at 1085 cm⁻¹ due to the vibration of Si-O-Si and at 931cm⁻¹ due to the vibration of Si-O-Al appeared after silica encapsulation. This verified that the silica encapsulation is not only a physical absorption process but also involving chemical bonding process. Both phosphors before and after encapsulation have same emission peak at 510 nm. A dense layer of silica formed on phosphor surface has the highest water-resistance after being encapsulated for 2h under the condition of pH 4 and encapsulation amount 10:1. The pH value of aqueous solution contained phosphor was steadily 8, and the initial afterglow brightness decreased only by 9%, that is, from 12101 to 11011 mcd/m².

Abstract: Eu²⁺, Dy³⁺ co-doped strontium aluminate (SrAl₂O₄) phosphor with high brightness and long afterglow were prepared by nano pseudo-boehmite particulate sol method. The precursor was prepared by peptizing AlOOH powders with HNO3 as peptize agent. The influence of preparation parameters on crystal structure and luminescent properties of the phosphor have been studied systematically. Monoclinic SrAl₂O₄ host with single-phase can be obtained by controlling sintering temperature at 1200°C, 4Wt%B2O3 and RSr/Al=0.34. The sample exhibits an intensive emission peak at 515 nm and the luminescent intensity decay with I=277.78t-1.079 .

Abstract: Zn2SiO4:Eu3+, Dy3+ phosphors have been prepared through the sol-gel process. X-ray diffraction (XRD), thermogravimetric and ddifferential thermal analysis (TG-DTA), FT-IR spectra and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1000oC. In Zn2SiO4:Eu3+,Dy3+ phosphors, the Eu3+ and Dy3+ show their characteristic red(613nm, 5D0-7F2), blue (481nm, 4F9/2–6H15/2) and yellow (577nm, 4F9/2–6H13/2) emissions.

Abstract: Phosphors of SrAl2O4:Eu2+, Dy3+ were encapsulated with polyethylene plastic film by a physical technology. Water resistance measurements, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, and photoluminescence (PL) spectrophotometry were used to characterize the phosphors Results showed that the encapsulated layer was a thin film with an encapsulation amount of 4.0 wt%, and encapsulation can effectively improve the water-resistance for the phosphor without any destroy of crystal structure of phosphors.

Abstract: A series of Sr0.95Al2O4:Eu2+0.02, Dy3+ 0.03•nB2O3 (0≤n≤0.30) were prepared by a solid state reaction. The role of B2O3 on the photoluminescence (PL) properties of Sr0.95Al2O4:Eu2+0.02, Dy3+0.03 were evaluated with UV emission spectra and decay curves. B2O3 significantly improved the emission intensity and persistent luminescence time. The crystal environment and defects induced by B3+ doping were detected with IR spectra, thermoluminescence and positron annihilation (PA) methods. Some Al3+ were substituted by B3+ and a kind of defect complex cluster responsible for the long decay time was formed when the substitution of Al3+ by B3+ occurs.

Abstract: Sr4Al14O25:Eu2+, Dy3+ long persistent phosphors with different B, Eu and Dy contents were prepared by solid phase reaction at various temperatures in H2/N2=1/9 atmosphere. X- ray diffraction and scanning electron microscopy observations showed that, when the phosphor was doped with 40 at% B, single dense Sr4Al14O25 phase was formed but for the samples with less than 40 at% B, mixed phases containing SrAl12O19 and SrAl2O4 were observed while for higher B content (100 at%) SrAl2B2O7 phases appeared. The phosphor showed emission peak centered at 500 nm with blue green color. When 40 at% of H3BO3 was added and doped with 4 at% of Eu and 8 at% of Dy, it showed the maximum initial intensity of 3170 mcd.m-2 and the longest persistency which is greater than 20 h over value of 5 mcd.m-2.

Abstract: Near-infrared emission properties of Dy3+-Tm3+ co-doped Ge-Ga-Sb-Se glasses were investigated. Possible energy transfer routes and the regime of donor decay were discussed. Tm3+ is found to be an efficient sensitizer on the Dy3+:1.34μm luminescence. Probable energy transfer schemes include Tm3+:3H4 → Dy3+: 6F5/2 and Tm3+:3H5 → Dy3+:6F11/2· 6H9/2. The donor (Tm3+) excitation is transferred to an acceptor (Dy3+) by direct interaction or migrates among donors by diffusion-limited regime until it comes into the vicinity of an energy acceptor where direct interaction and transfer occur.