Intense Emission of Ca[sub 5](PO[sub 4])[sub 3]F:Tb[sup 3+] under VUV Excitation and Its Potential Application in PDPs

Abstract

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...

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