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 Ca 5 (PO 4 ) 3 F. In contrast, Ce 3+ ions mainly occupied the Sr(II)/Ba(II) sites in Sr 5 (PO 4 ) 3 F and Ba 5 (PO 4 ) 3 F even at higher doping concentration. The low light output seems to suggest that the materials are not suitable x-ray or gamma-ray phosphors.

In order to develop a suitable green phosphor for plasma display panels ͑PDPs͒, 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 Ͻ 200 nm and the energy E Ͼ 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 ͑VUV͒ range, exhibits higher intensive emission under 147/172 nm excitation, and has a shorter decay time ͑ ϳ 2.19 ms͒ 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.Plasma display panels ͑PDPs͒ have been widely used as large flat-panel-display devices, in which the phosphors are excited by vacuum ultraviolet ͑VUV, wavelength Ͻ 200 nm, energy E Ͼ 50,000 cm −1 ͒ photons consisting of the Xe resonance emission line ͑147 nm͒ and the Xe 2 molecular emission band ͑172 nm͒. The performances of PDPs are directly related to the luminescent properties of phosphors. Today, Zn 2 SiO 4 /Mn 2+ ͑ZSM͒ is commonly used as a green PDP phosphor. 1,2 The primary drawback of ZSM is its longer decay time. When ZSM is used, a green afterglow would blur the image for rapid-moving pictures. 3,4 So, it is urgent to find a suitable green PDP phosphor, which should show some good characteristics such as strong and broad absorption around 147/172 nm and intensive emission under 147/172 nm excitation with a shorter decay time.Calcium fluorapatite Ca 5 ͑PO 4 ͒ 3 F ͑FAP͒ is well known for its lighting importance. The phosphors Ca 5 ͑PO 4 ͒ 3 X:Sb 3+ ,Mn 2+ ͑X = F, Cl͒ were invented in 1942 and have been main phosphors in fluorescent lamp until now. 5,6 Trivalent terbium-activated materials have been demonstrated to be practicable efficient green phosphors. In the past years, researchers have confirmed display and lighting applications of Tb 3+ in a number of hosts. 7-9 In the present study, a promising green PDP phosphor Ca 5−2x Tb x Na x ͑PO 4 ͒ 3 F is demonstrated. ExperimentalPowder samples Ca 5−2x Tb x Na x ͑PO 4 ͒ 3 F ͑for x = 0, 0.20, 0.35, 0.50, 0.65, 0.80, and 0.95, these values directly show the doping concentration of Tb 3+ in the samples͒ were prepared by a hightemperature solid-state reaction technique. The stoichiometric mixtures of analytical-grade purity CaCO 3 , CaHPO 4 ·2H 2 O, Na 2 CO 3 , NH 4 F ͑excess 10 mol %͒, and 99.9% purity Tb 4 O 7 were heated at 1100°C for 2 h under CO atmosphere. The final products were obtained by washing the samples with distilled water and then drying. Because trivalent Tb 3+ are located on divalent Ca 2+ sites, some sort of charge-compensating defect is built in the lattices; therefore, Na + ions provided by Na 2 CO 3 were added as a charge-compensating defect.The structure of the samples was examined by powder X-ray diffraction ͑PXRD͒ using Cu K␣ radiation on a Rigaku D/max 2200 vpc X-ray diffractometer.Th...

No abstract

No abstract