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A novel red phosphor Na2Ca4Mg2Si4O15:Eu3+ for plasma display panels
Materials Research Bulletin 43 (2008) 2295–2299 www.elsevier.com/locate/matresbu
A novel red phosphor Na2Ca4Mg2Si4O15:Eu3+ for plasma display panels Li-Ya Zhou a,*, Fu-Zhong Gong a, Jian-Xin Shi b, Meng-Lian Gong b, Hong-Bin Liang b b
a School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, People’s Republic of China State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China
Received 27 March 2007; received in revised form 27 July 2007; accepted 3 August 2007 Available online 10 August 2007
Abstract A novel red emitting phosphor, Eu3+-doped Na2Ca4Mg2Si4O15, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Na2Ca4Mg2Si4O15:Eu3+. Field-emission scanning electron-microscopy (FESEM) observation indicated a narrow size-distribution of about 300 nm for the particles with spherical shape. Upon excitation with vacuum ultraviolet (VUV) and near UV light, the phosphor showed strong red-emission lines at around 611 and 617 nm, respectively, corresponding to the forced electric dipole 5D0 ! 7F2 transition of Eu3+, and the highest PL intensity at 617 nm was found at a content of about 8 mol% Eu3+. The optical properties study suggests that it is a potential candidate for plasma display panels (PDPs) application. # 2007 Elsevier Ltd. All rights reserved. Keywords: A. Optical materials; C. X-ray diffraction; D. Luminescence
1. Introduction Plasma display panels (PDPs) is the most promising candidate for large size flat-panel information-display devices. Moreover, it offers wide viewing angle, fast response, low energy consumption and other advantages [1– 3]. As phosphors play a key role in the performances of the devices, much research has been made in exploring good phosphors for application in PDPs in recent years [4–7]. Phosphors in the PDPs are excited by VUV radiation lines of Xe atoms at 147 nm and Xe2 molecular at 172 nm; therefore thermally stability, high luminous efficiency, radiation resistivity, fine particle size and narrow size distribution are required for the phosphors. At present, the most widely used red phosphor for PDPs is (YGd) BO3:Eu3+ because of its high luminescence efficiency under VUV excitation. Although it is a good phosphor widely used in plasma display panels, this phosphor has the poor CIE coordinates due to the sharp emission line around 593 nm and the long decay time, which make it insufficient to reproduce a color of picture [8]. Thus special attention has been paid to phosphors with efficient VUV-excited and shorter decay time. For high efficient phosphor in PDPs, the host lattice or the
* Corresponding author. Tel.: +86 771 3272881; fax: +86 771 3233718. E-mail address: [email protected] (L.-Y. Zhou). 0025-5408/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.materresbull.2007.08.014
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activators must have strong absorption in the range between 140 and 180 nm. Some oxide compounds with silicate, borate and aluminate groups have strong absorption in the VUV region [2,9]. Silicates are of interest as host lattices for luminescent ions, because of their high physical and chemical stability. In this paper, a Eu3+doped silicate, Na2Ca4Mg2Si4O15:Eu3+, was prepared by solid-state method. To the best of our knowledge, this is the first report about the synthesis and VUV luminescence properties of Na2Ca4Mg2Si4O15:Eu3+. X-ray diffraction, field emission scan electron microscopy and photoluminescence (PL) measurements were used to characterize the Na2Ca4Mg2Si4O15:Eu3+ phosphor. 2. Experimental 2.1. Preparation of Na2Ca4Mg2Si4O15:Eu3+ phosphor The phosphors Na2Ca4Mg2Si4O15:Eu3+ were prepared by solid-state reaction method at high temperature. Reagents CaCO3, SiO2, (MgCO3)4Mg(OH)25H2O, Na2CO3 (A.R., Brilliance reagent factory of Shantou) and Eu2O3 (99.99%, Pearl River smeltery) were used for sample preparations. Stoichiometric amount of starting materials were mixed homogeneously in an agate mortar and pre-calcined at 500 8C for 3 h, then calcined at 1100 8C for 5 h. 2.2. Characterization of Na2Ca4Mg2Si4O15:Eu3+phosphor ˚ Rigaku/Dmax-2200) was used for crystal Powder X-ray diffraction (XRD, 40 kV and 35 mA, Cu Ka = 1.5406 A phase identification. Field emission scan electron microscopy (JSM-6330F) was used to observe the morphology and size of the calcined particles. The lifetime of the samples were taken on an FLS920 luminescence spectrometer. Near UV excitation and emission spectra were measured on a HITACHI F-4500 fluorescence spectrophotometer use a Xe lamp as the excitation source. The VUV excitation spectra and the luminescent spectra under VUV excitation were measured at the time-resolved spectroscopy experimental station on beam line U24 of National Synchrotron Radiation Laboratory (NSRL). The electron energy of the storage ring is 800 MeV, and the beam current is about 100–200 mA. At time-resolved spectroscopy experimental station, a Seya-Namioka monochromator (1200 g/mm, 100–400 nm) is used for the synchrotron radiation excitation photon, an ARC-257 monochromator (1200 g/mm, 330–700 nm) for the emission photon and the signal is detected by a Hamamatsu H5920-01 photomultiplier. The resolution of the instruments is about 0.2 nm. The pressure in the sample chamber is about 1 103 Pa. All the measurements were carried out at room temperature.
Fig. 1. XRD patterns of the Na2Ca4Mg2Si4O15:2 mol% Eu3+ phosphor calcined at (a) 1000 8C, (b) 1100 8C and (c) 1200 8C for 5 h.
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3. Results and discussion The powder XRD patterns of the samples were shown in Fig. 1, and a–c were patterns for the samples calcined for 5 h in air at 1000, 1100 and 1200 8C, respectively. When the precursor was calcined at 1000 8C, the characteristic peaks of Na2Ca4Mg2Si4O15 (ICDD 42-1484) appear with the existing peaks of CaO (ICDD 28-0775). At 1100 8C, however, Na2Ca4Mg2Si4O15 form without impurity phase. When the temperature is increased to 1200 8C, the intensity of the peaks does not change significantly, and no new peaks are observed. Once the temperature is high as 1300 8C, a melt form with Na2Ca4Mg2Si4O15 composition formed. So the optimum firing temperature is about 1100 8C. Eu3+doping did not change the lattice of the powder. Fig. 2 shows the FE-SEM image of Na2Ca4Mg2Si4O15:2 mol% Eu3+ particles calcined at 1100 8C for 5 h. The particles showed a narrow size-distribution of about 300 nm with spherical shape. There was only a little aggregation for the particles because decomposition of the (MgCO3)4Mg(OH)25H2O and release of a mass of CO2 gas reduced the aggregation.
Fig. 2. FE-SEM image of Na2Ca4Mg2Si4O15:2 mol% Eu3+ phosphor calcined at 1100 8C for 5 h.
Fig. 3. Room-temperature UV excitation (lem = 617 nm) and emission (lex = 395 nm) spectra of Na2Ca4Mg2Si4O15:Eu3+ phosphors with different Eu3+ doping ratios.
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Fig. 3 shows the near UV excitation and emission spectra of the Na2Ca4Mg2Si4O15:Eu3+ samples. The excitation spectrum consists of a strong broad band around 230–300 nm and a series of sharp lines between 310 and 410 nm. The strong broad band was attributed to the ligand to metal charge-transfer (CT) state from the O2–Eu3+, and the sharp lines correspond to the f–f transitions of Eu3+ ions [10,11]. The broad charge-transfer band also confirms the presence of the Eu3+ ions into the Na2Ca4Mg2Si4O15 host matrices. Upon excitation with 395 nm UV irradiation, the spectra are described by the well-known 5D0 ! 7FJ (J = 0, 1, 2,. . .) emission lines of the Eu3+ ions with the strong emission for J = 2 at 617 nm. If there is no inversion symmetry at the site of the rare earth ion, the electric dipole transitions exist, and the 5D0 ! 7F2 transition can be observed, which is sensitive to the ligand environment [12]. In the emission spectra of Na2Ca4Mg2Si4O15:Eu3+, the electric dipole 5D0 ! 7F2 transition around 617 nm is stronger than that of the magnetic dipole 5D0 ! 7F1 transition around 594 nm. This indicates that Eu3+ ions occupy the non-inversion symmetric sites in the host lattice. Due to the differences in valence states and ion sizes between Mg2+ (65 pm)and Eu3+ (95 pm), Eu3+ ions substitute the Ca2+ (99 pm) site. A ratio between the integrated intensity of these two transitions, I0–2/I0–1, is used in lanthanide-based systems as a probe of the cation local surroundings [13]. As showed in Fig. 3, the transition 5D0 ! 7F2 is much stronger than the transition 5D0 ! 7F1 and the ratio of I0–2/I0–1, is about 1.65, which suggests that the Eu3+ located in a distorted (or asymmetric) cation environment. This is in favorable to improve the color purity of the red phosphor. The effect of the doped-Eu3+ content in Na2Ca4Mg2Si4O15:Eu3+ phosphor on the relative PL intensity at highest 5D0 ! 7F2 transition were also shown in Fig. 3. Usually, a low doping ratio gives weak luminescence while an over-doping ratio perhaps brings quenching of the luminescence. From Fig. 3 it can be seen that the luminescence intensity is enhanced as the increasing of the Eu3+ doping ratio and reaches a maximum at 8 mol% of Eu3+. When the Eu3+ doping ratio is higher above 8 mol%, the luminescence intensity reduces contrarily. This quenching process is usually attributed to energy migration among Eu3+ ions, which bring the excitation energy to killer sites such as surface defects in powders. The lifetime measurement was taken and based on a single exponential method, the decays time of the Na2Ca4Mg2Si4O15:Eu3+ phosphor monitored at 617 nm and excited at 395 nm is about 1.95 ms, which was short and suitable for PDP application. The VUV excitation and emission spectra are shown in Fig. 4. The excitation spectrum consists of two broad bands with maxima at about 145 and 235 nm, respectively monitored at 611 nm. The VUV band from 140 to 200 nm is the band gap absorption region of the host lattice (silicate) [14,15]. The broad band at 235 nm is attributed to the charge transfer band (CT band) resulting from an electron transfer between the ligand O2 orbit and the empty states of the 4f6 configuration of Eu3+. This result reveals that there is an efficient energy transfer from the host to the Eu3+ ions. The emission spectrum of Na2Ca4Mg2Si4O15:Eu3+ excited by VUV source at the wavelength of 172 nm exhibits brightly red emission at 611 nm and the ratio of I0–2/I0–1 is 1.66, showing a better color purity and CIE coordinates than that of the currently used PDP red phosphor (YGd) BO3:Eu3+. Therefore, the novel phosphor Na2Ca4Mg2Si4O15:Eu3+ is a potentially good candidate for PDP application.
Fig. 4. Room-temperature VUV excitation (lem = 611 nm)and emission (lex = 172 nm) spectrum of Na2Ca4Mg2Si4O15:8 mol% Eu3+ phosphor.
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4. Conclusions Na2Ca4Mg2Si4O15:Eu3+ phosphors with a spherical shape and a size about 300 nm were prepared using solid-state methods. Upon excitation with VUV and near UV light excitation, the phosphor showed strong red-emission lines at around 611 and 617 nm, respectively, corresponding to the forced electric dipole 5D0 ! 7F2 transition of Eu3+. The VUV excitation spectra show two broad bands in 100–300 nm range, and there is an energy transfer from the host to the Eu3+ ions. Therefore, the novel phosphor Na2Ca4Mg2Si4O15:Eu3+ is a potentially good candidate for PDP application. Acknowledgements This work was financially supported by grants from the Science Foundation of Guangxi Province (No. 0731014), the Natural Science Foundation of Guangxi University (X051107), the Natural Science Foundation of Guangdong Province (No. 021716) and the Scientific and Technical Projects of Guangdong Province (B10502). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
C.R. Ronda, T. Justel, H. Nikol, J. Alloys Compd. 275–277 (1998) 669. C.H. Kim, E. Kwon, C.H. Park, Y.J. Hwang, H.S. Bae, B.Y. Yu, C.H. Pyun, G.Y. Hong, J. Alloys Compd. 311 (2000) 33. R.P. Rao, D.J. Devine, J. Lumin. 87–89 (2000) 1260. L.H. Tian, B.Y. Yu, C.H. Pyun, H.L. Park, S.I. Mho, Solid State Commun. 129 (2004) 43. H.P. You, G.Y. Hong, X.Q. Zeng, C.-H. Kim, C.-H. Pyun, B.-Y. Yu, H.-S. Bar, J. Phys. Chem. Solids 61 (2000) 1985. B. Moine, G. Bizarri, Mater. Sci. Eng. B 105 (2003) 2. H.B. Liang, Y. Tao, Q. Su, S.B. Wang, J. Solid State Chem. 167 (2002) 435. E.J. Kim, Y.C. Kang, H.D. Park, S.K. Ryu, Mater. Res. Bull. 38 (2003) 515. C.R. Ronda, J. Lumin. 72–74 (1997) 49. G. Blasse, J. Chem. Phys. 45 (1966) 2356. D. van der Voort, J.M.E. de Rijk, R. van Doorn, G. Blasse, Mater. Chem. Phys. 31 (1992) 333. S. Shionoya, W.M. Yen, Phosphor Handbook, CRC Press, Boca Raton, 1999, p. 190. J.P. Rainho, L.D. Carlos, J. Rocha, J. Lumin. 87–89 (2000) 1083. S. Tanaka, I. Ozaki, T. Kumimoto, K. Ohmi, H. Kobayashi, J. Lumin. 87–89 (2000) 1250. C.H. Park, S.J. Park, B.Y. Yu, H.S. Bae, C.H. Kim, C.H. Pyun, H.G. Yan, J. Mater. Sci. Lett. 19 (2000) 335.
A novel red phosphor Na2Ca4Mg2Si4O15:Eu3+ for plasma display panels Li-Ya Zhou a,*, Fu-Zhong Gong a, Jian-Xin Shi b, Meng-Lian Gong b, Hong-Bin Liang b b
a School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, People’s Republic of China State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China
Received 27 March 2007; received in revised form 27 July 2007; accepted 3 August 2007 Available online 10 August 2007
Abstract A novel red emitting phosphor, Eu3+-doped Na2Ca4Mg2Si4O15, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Na2Ca4Mg2Si4O15:Eu3+. Field-emission scanning electron-microscopy (FESEM) observation indicated a narrow size-distribution of about 300 nm for the particles with spherical shape. Upon excitation with vacuum ultraviolet (VUV) and near UV light, the phosphor showed strong red-emission lines at around 611 and 617 nm, respectively, corresponding to the forced electric dipole 5D0 ! 7F2 transition of Eu3+, and the highest PL intensity at 617 nm was found at a content of about 8 mol% Eu3+. The optical properties study suggests that it is a potential candidate for plasma display panels (PDPs) application. # 2007 Elsevier Ltd. All rights reserved. Keywords: A. Optical materials; C. X-ray diffraction; D. Luminescence
1. Introduction Plasma display panels (PDPs) is the most promising candidate for large size flat-panel information-display devices. Moreover, it offers wide viewing angle, fast response, low energy consumption and other advantages [1– 3]. As phosphors play a key role in the performances of the devices, much research has been made in exploring good phosphors for application in PDPs in recent years [4–7]. Phosphors in the PDPs are excited by VUV radiation lines of Xe atoms at 147 nm and Xe2 molecular at 172 nm; therefore thermally stability, high luminous efficiency, radiation resistivity, fine particle size and narrow size distribution are required for the phosphors. At present, the most widely used red phosphor for PDPs is (YGd) BO3:Eu3+ because of its high luminescence efficiency under VUV excitation. Although it is a good phosphor widely used in plasma display panels, this phosphor has the poor CIE coordinates due to the sharp emission line around 593 nm and the long decay time, which make it insufficient to reproduce a color of picture [8]. Thus special attention has been paid to phosphors with efficient VUV-excited and shorter decay time. For high efficient phosphor in PDPs, the host lattice or the
* Corresponding author. Tel.: +86 771 3272881; fax: +86 771 3233718. E-mail address: [email protected] (L.-Y. Zhou). 0025-5408/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.materresbull.2007.08.014
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activators must have strong absorption in the range between 140 and 180 nm. Some oxide compounds with silicate, borate and aluminate groups have strong absorption in the VUV region [2,9]. Silicates are of interest as host lattices for luminescent ions, because of their high physical and chemical stability. In this paper, a Eu3+doped silicate, Na2Ca4Mg2Si4O15:Eu3+, was prepared by solid-state method. To the best of our knowledge, this is the first report about the synthesis and VUV luminescence properties of Na2Ca4Mg2Si4O15:Eu3+. X-ray diffraction, field emission scan electron microscopy and photoluminescence (PL) measurements were used to characterize the Na2Ca4Mg2Si4O15:Eu3+ phosphor. 2. Experimental 2.1. Preparation of Na2Ca4Mg2Si4O15:Eu3+ phosphor The phosphors Na2Ca4Mg2Si4O15:Eu3+ were prepared by solid-state reaction method at high temperature. Reagents CaCO3, SiO2, (MgCO3)4Mg(OH)25H2O, Na2CO3 (A.R., Brilliance reagent factory of Shantou) and Eu2O3 (99.99%, Pearl River smeltery) were used for sample preparations. Stoichiometric amount of starting materials were mixed homogeneously in an agate mortar and pre-calcined at 500 8C for 3 h, then calcined at 1100 8C for 5 h. 2.2. Characterization of Na2Ca4Mg2Si4O15:Eu3+phosphor ˚ Rigaku/Dmax-2200) was used for crystal Powder X-ray diffraction (XRD, 40 kV and 35 mA, Cu Ka = 1.5406 A phase identification. Field emission scan electron microscopy (JSM-6330F) was used to observe the morphology and size of the calcined particles. The lifetime of the samples were taken on an FLS920 luminescence spectrometer. Near UV excitation and emission spectra were measured on a HITACHI F-4500 fluorescence spectrophotometer use a Xe lamp as the excitation source. The VUV excitation spectra and the luminescent spectra under VUV excitation were measured at the time-resolved spectroscopy experimental station on beam line U24 of National Synchrotron Radiation Laboratory (NSRL). The electron energy of the storage ring is 800 MeV, and the beam current is about 100–200 mA. At time-resolved spectroscopy experimental station, a Seya-Namioka monochromator (1200 g/mm, 100–400 nm) is used for the synchrotron radiation excitation photon, an ARC-257 monochromator (1200 g/mm, 330–700 nm) for the emission photon and the signal is detected by a Hamamatsu H5920-01 photomultiplier. The resolution of the instruments is about 0.2 nm. The pressure in the sample chamber is about 1 103 Pa. All the measurements were carried out at room temperature.
Fig. 1. XRD patterns of the Na2Ca4Mg2Si4O15:2 mol% Eu3+ phosphor calcined at (a) 1000 8C, (b) 1100 8C and (c) 1200 8C for 5 h.
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3. Results and discussion The powder XRD patterns of the samples were shown in Fig. 1, and a–c were patterns for the samples calcined for 5 h in air at 1000, 1100 and 1200 8C, respectively. When the precursor was calcined at 1000 8C, the characteristic peaks of Na2Ca4Mg2Si4O15 (ICDD 42-1484) appear with the existing peaks of CaO (ICDD 28-0775). At 1100 8C, however, Na2Ca4Mg2Si4O15 form without impurity phase. When the temperature is increased to 1200 8C, the intensity of the peaks does not change significantly, and no new peaks are observed. Once the temperature is high as 1300 8C, a melt form with Na2Ca4Mg2Si4O15 composition formed. So the optimum firing temperature is about 1100 8C. Eu3+doping did not change the lattice of the powder. Fig. 2 shows the FE-SEM image of Na2Ca4Mg2Si4O15:2 mol% Eu3+ particles calcined at 1100 8C for 5 h. The particles showed a narrow size-distribution of about 300 nm with spherical shape. There was only a little aggregation for the particles because decomposition of the (MgCO3)4Mg(OH)25H2O and release of a mass of CO2 gas reduced the aggregation.
Fig. 2. FE-SEM image of Na2Ca4Mg2Si4O15:2 mol% Eu3+ phosphor calcined at 1100 8C for 5 h.
Fig. 3. Room-temperature UV excitation (lem = 617 nm) and emission (lex = 395 nm) spectra of Na2Ca4Mg2Si4O15:Eu3+ phosphors with different Eu3+ doping ratios.
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Fig. 3 shows the near UV excitation and emission spectra of the Na2Ca4Mg2Si4O15:Eu3+ samples. The excitation spectrum consists of a strong broad band around 230–300 nm and a series of sharp lines between 310 and 410 nm. The strong broad band was attributed to the ligand to metal charge-transfer (CT) state from the O2–Eu3+, and the sharp lines correspond to the f–f transitions of Eu3+ ions [10,11]. The broad charge-transfer band also confirms the presence of the Eu3+ ions into the Na2Ca4Mg2Si4O15 host matrices. Upon excitation with 395 nm UV irradiation, the spectra are described by the well-known 5D0 ! 7FJ (J = 0, 1, 2,. . .) emission lines of the Eu3+ ions with the strong emission for J = 2 at 617 nm. If there is no inversion symmetry at the site of the rare earth ion, the electric dipole transitions exist, and the 5D0 ! 7F2 transition can be observed, which is sensitive to the ligand environment [12]. In the emission spectra of Na2Ca4Mg2Si4O15:Eu3+, the electric dipole 5D0 ! 7F2 transition around 617 nm is stronger than that of the magnetic dipole 5D0 ! 7F1 transition around 594 nm. This indicates that Eu3+ ions occupy the non-inversion symmetric sites in the host lattice. Due to the differences in valence states and ion sizes between Mg2+ (65 pm)and Eu3+ (95 pm), Eu3+ ions substitute the Ca2+ (99 pm) site. A ratio between the integrated intensity of these two transitions, I0–2/I0–1, is used in lanthanide-based systems as a probe of the cation local surroundings [13]. As showed in Fig. 3, the transition 5D0 ! 7F2 is much stronger than the transition 5D0 ! 7F1 and the ratio of I0–2/I0–1, is about 1.65, which suggests that the Eu3+ located in a distorted (or asymmetric) cation environment. This is in favorable to improve the color purity of the red phosphor. The effect of the doped-Eu3+ content in Na2Ca4Mg2Si4O15:Eu3+ phosphor on the relative PL intensity at highest 5D0 ! 7F2 transition were also shown in Fig. 3. Usually, a low doping ratio gives weak luminescence while an over-doping ratio perhaps brings quenching of the luminescence. From Fig. 3 it can be seen that the luminescence intensity is enhanced as the increasing of the Eu3+ doping ratio and reaches a maximum at 8 mol% of Eu3+. When the Eu3+ doping ratio is higher above 8 mol%, the luminescence intensity reduces contrarily. This quenching process is usually attributed to energy migration among Eu3+ ions, which bring the excitation energy to killer sites such as surface defects in powders. The lifetime measurement was taken and based on a single exponential method, the decays time of the Na2Ca4Mg2Si4O15:Eu3+ phosphor monitored at 617 nm and excited at 395 nm is about 1.95 ms, which was short and suitable for PDP application. The VUV excitation and emission spectra are shown in Fig. 4. The excitation spectrum consists of two broad bands with maxima at about 145 and 235 nm, respectively monitored at 611 nm. The VUV band from 140 to 200 nm is the band gap absorption region of the host lattice (silicate) [14,15]. The broad band at 235 nm is attributed to the charge transfer band (CT band) resulting from an electron transfer between the ligand O2 orbit and the empty states of the 4f6 configuration of Eu3+. This result reveals that there is an efficient energy transfer from the host to the Eu3+ ions. The emission spectrum of Na2Ca4Mg2Si4O15:Eu3+ excited by VUV source at the wavelength of 172 nm exhibits brightly red emission at 611 nm and the ratio of I0–2/I0–1 is 1.66, showing a better color purity and CIE coordinates than that of the currently used PDP red phosphor (YGd) BO3:Eu3+. Therefore, the novel phosphor Na2Ca4Mg2Si4O15:Eu3+ is a potentially good candidate for PDP application.
Fig. 4. Room-temperature VUV excitation (lem = 611 nm)and emission (lex = 172 nm) spectrum of Na2Ca4Mg2Si4O15:8 mol% Eu3+ phosphor.
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4. Conclusions Na2Ca4Mg2Si4O15:Eu3+ phosphors with a spherical shape and a size about 300 nm were prepared using solid-state methods. Upon excitation with VUV and near UV light excitation, the phosphor showed strong red-emission lines at around 611 and 617 nm, respectively, corresponding to the forced electric dipole 5D0 ! 7F2 transition of Eu3+. The VUV excitation spectra show two broad bands in 100–300 nm range, and there is an energy transfer from the host to the Eu3+ ions. Therefore, the novel phosphor Na2Ca4Mg2Si4O15:Eu3+ is a potentially good candidate for PDP application. Acknowledgements This work was financially supported by grants from the Science Foundation of Guangxi Province (No. 0731014), the Natural Science Foundation of Guangxi University (X051107), the Natural Science Foundation of Guangdong Province (No. 021716) and the Scientific and Technical Projects of Guangdong Province (B10502). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
C.R. Ronda, T. Justel, H. Nikol, J. Alloys Compd. 275–277 (1998) 669. C.H. Kim, E. Kwon, C.H. Park, Y.J. Hwang, H.S. Bae, B.Y. Yu, C.H. Pyun, G.Y. Hong, J. Alloys Compd. 311 (2000) 33. R.P. Rao, D.J. Devine, J. Lumin. 87–89 (2000) 1260. L.H. Tian, B.Y. Yu, C.H. Pyun, H.L. Park, S.I. Mho, Solid State Commun. 129 (2004) 43. H.P. You, G.Y. Hong, X.Q. Zeng, C.-H. Kim, C.-H. Pyun, B.-Y. Yu, H.-S. Bar, J. Phys. Chem. Solids 61 (2000) 1985. B. Moine, G. Bizarri, Mater. Sci. Eng. B 105 (2003) 2. H.B. Liang, Y. Tao, Q. Su, S.B. Wang, J. Solid State Chem. 167 (2002) 435. E.J. Kim, Y.C. Kang, H.D. Park, S.K. Ryu, Mater. Res. Bull. 38 (2003) 515. C.R. Ronda, J. Lumin. 72–74 (1997) 49. G. Blasse, J. Chem. Phys. 45 (1966) 2356. D. van der Voort, J.M.E. de Rijk, R. van Doorn, G. Blasse, Mater. Chem. Phys. 31 (1992) 333. S. Shionoya, W.M. Yen, Phosphor Handbook, CRC Press, Boca Raton, 1999, p. 190. J.P. Rainho, L.D. Carlos, J. Rocha, J. Lumin. 87–89 (2000) 1083. S. Tanaka, I. Ozaki, T. Kumimoto, K. Ohmi, H. Kobayashi, J. Lumin. 87–89 (2000) 1250. C.H. Park, S.J. Park, B.Y. Yu, H.S. Bae, C.H. Kim, C.H. Pyun, H.G. Yan, J. Mater. Sci. Lett. 19 (2000) 335.