Zifeng Tian

Luminescence of Ce3+ activated fluoro-apatites M5(PO4)3F (M = Ca, Sr, Ba) under VUV—UV and x-ray excitation

Fluoro-apatite M5(PO4)3 F( M= Ca, Sr, Ba) phosphors activated with Ce 3+ ions were prepared by a solid state reaction technique at high temperature. The excitation spectra in the VUV (vacuum ultraviolet)–UV range and the emission spectra in the UV–vis range together with decay time spectra are investigated and discussed. X-ray excited emission spectra were measured and light yields are calculated. The results revealed that Ca(II) sites are preferentially occupied at low doping concentration, and then Ca(I) sites are dominant with the increasing of concentration for Ce 3+ in Ca5(PO4)3F. In contrast, Ce 3+ ions mainly occupied the Sr(II)/Ba(II) sites in Sr5(PO4)3 Fa nd Ba5(PO4)3F even at higher doping concentration. The low light output seems to suggest that the materials are not suitable x-ray or gamma-ray phosphors. (Some figures in this article are in colour only in the electronic version)

Intensive emission of Dy 3+ in NaGd(PO 3 ) 4 for Hg-free lamps application

The phosphor NaGd(PO(3))(4):Dy(3+) was synthesized by solid-state reaction technique at high temperature. The vacuum ultraviolet (VUV)-UV excitation spectra and visible emission spectra under VUV/UV excitation were investigated. The sample NaGd(PO(3))(4):Dy(3+) showed suitable spectroscopic characteristics such as broad and strong absorption around 172 nm, intensive emission with the chromaticity coordinates (0.33, 0.38) in warm-white light region. Additionally, this efficient white-emitting phosphor is activated by a single Dy(3+) ion and with a lower preparation temperature, which tend to decrease the consumption of rare earth resource and energy. Therefore, the phosphor NGP:Dy(3+) may be considered as a suitable candidate for Hg-free lamps application.

Intense Emission of Ca5 ( PO4 ) 3F : Tb3 + under VUV Excitation and Its Potential Application in PDPs

In order to develop a suitable green phosphor for plasma display panels (PDPs), samples Ca 5-2x Tb x Na x (PO 4 ) 3 F for x = 0.20, 0.35, 0.50, 0.65, 0.80, and 0.95 were prepared by a solid-state reaction technique at high temperature. The vacuum ultraviolet (VUV, wavelength λ 50,000 cm -1 )-vis spectroscopic properties and decay characteristic were investigated. Because the phosphor Ca 5-2x Tb x Na x (PO 4 ) 3 F for x = 0.95 shows broad and strong absorption in the vacuum ultraviolet (VUV) range, exhibits higher intensive emission under 147/172 nm excitation, and has a shorter decay time (τ ∼ 2.19 ms) in comparison with the commercial green PDP phosphor Zn 2 SiO 4 /Mn 2+ , it is considered to be a promising green phosphor in PDPs.

Luminescence of Ba2Ca(BO3)2 : Ce3+—influence of charge compensator, energy transfer and LED application

The luminescence properties of Ce3+ activated Ba2Ca(BO3)2 with K+ as a charge compensator have been investigated and compared with those with Na+-compensating. Energy transfer of Ce3+ in Ba2+ (i.e. Ce(1)3+) and Ca2+ (i.e. Ce(2)3+) sites has been proven by VUV?UV excitation and emission spectra, luminescence decays and time-resolved emission spectra. In addition, by combining Ba2Ca(BO3)2?:?Ce3+ phosphors with near-ultraviolet (n-UV) InGaN chips, the fabricated light-emitting diodes (LEDs) show intense bluish-green emission, and the phosphors exhibit good thermal stability.

Efficient emission-tunable VUV phosphors Na 2 GdF 2 PO 4 :Tb 3+

In this paper, we present the VUV-vis spectroscopic properties of Na(2)GdF(2)PO(4):Tb(3+) phosphors prepared at 700 degrees C. The phosphors exhibit some favorable luminescence characteristics such as intensive and broad absorption near 147/172 nm, high bright emission in whole doping concentration, and tunable chromaticity coordinates from blue to whitish and further to yellowish-green range by changing the doping concentration of Tb(3+). As a result, this series of phosphors Na(2)Gd(1-x)Tb(x)F(2)PO(4) can be considered as promising candidates for plasma display panels (PDPs) and Hg-free fluorescent tubes application.

The VUV‐VIS Spectroscopic Properties of Dy3+ Ion in Phosphors M5‐2XDyXNaX(PO4)3F (M=Ca, Sr, Ba) and Their Potential Applications in Mercury‐Free Lamps

Abstract The phosphors, fluorapatites M5(PO4)3F (M=Ca, Sr, Ba) activated with Dy3+ ions, were prepared by a high‐temperature solid‐state reaction technique. The VUV‐UV excitation spectra and emission spectra under VUV/UV excitation were measured. The phosphors show broad and strong absorption near 172 nm and intensive emission with the chromaticity coordinates entering the white light region. Hence, the phosphors may be considered as suitable candidates for Hg‐free lamps.

High-power laser-driven phosphor-in-glass for excellently high conversion efficiency white light generation for special illumination or display backlighting

High-power and high-brightness solid state laser lighting sources, fabricated with high-power blue laser diodes (LDs) and yellow-emitting phosphor converters, constitute a pioneering lighting technology for specialized lighting. Because of the high radiation flux and thermal stress produced by high-power blue LDs, there is an urgent need for a light converter with excellent heat-resistance and thermal stability. In this work, YAG:Ce phosphor-in-glass (PiG), prepared by embedding YAG:Ce phosphor in glass matrix, was developed. Because of the good chemical stability between the glass matrix and the phosphor as well as high refractive index of 1.84 of the glass matrix, the internal quantum efficiency of YAG:Ce-PiG material can reach up to 78.9% under 445 nm blue laser excitation. In comparison with reported papers, the content of the YAG phosphor in this PiG can reach up to 29 wt%, thus it can get more brightness when excited by higher LD power. Besides, systematic research on the thermal effect to the material and its luminescent properties when excited by a high-power blue LD is done in detail. Compared with traditional commercial phosphor-in-silicone (PiS) light converters, PiG can withstand higher blue LD power and maintain a higher luminescent intensity. By virtue of its better heat-resistance performance under exposure to high-power blue LD, the developed PiG light converter material is an ideal choice to replace traditional commercial PiS in high brightness lighting sources.