A New Promising X-Ray Storage Phosphor BaBrCl：Eu^2＋

Photostimulated luminescence was observed in X-ray irradiated BaBrCl doped with Eu^2 ＋ . It shows an emission band that peak at 413 nm, and two difference absorption spectra （DAS） bands that peak at - 550 nm and 675 nm respectively. The stimulation energy is lower than that of BaFX：Eu^2＋ （X = Cl, Br）, and matches the cheaper, more portable, and more convenient semiconductor laser better. The results indicate that BaBrCl ： Eu^2＋ shows positive potential as a promising X-ray storage phosphor for practical utilization.     

Colour Centres and Energy Transfer in BaF2-xClx:Eu2+ Phosphors

The optical absorption spectra of BaF2-xClx:Eu2 after ultraviolet (UV) light excitation were investigated.The differences between the absorption spectra after and before excitation (DAS) were observed.The DAS increase at both the high and the low energy side of F band in BaF2-xClx:Eu2 after 245 nm UV light excitation.The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres (association of F(Cl-) centres), whose absorption band matches the HeNe laser better, may explain the latter.In the write-in process, the transfer of electrons is via tunneling.In the readout process, the transfer of electrons captured in F(F-) and Fa centres is more likely via tunneling, and that of F(Cl-) centres is more likely via conduction band.     

Effect of TSL and PSL in Al^3＋-Doped BaFBr：Eu^2＋ at Difference Synthesis Conditions

Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al^3 -doped BaFBr:Eu^2 in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al^3 -doped BaFBr:Eu^2 by different synthetic conditions. The relationship of color center‘s energy and different synthetic conditions is discussed.     

A New Promising X-Ray Storage Phosphor BaBrCl∶Eu~(2+)

Digital radiography of X-rays using X-ray storagephosphors as screens has become increasingly avail-able commercially ,particularly those that are used inmedical diagnostics[1]. A large number of storagephosphors have been studied ,including BaFX∶Eu2 +(X=Cl ,Br ,I)[2 ~5],alkali halides doped with Eu2 +(or Ga+)[6 ,7], BaLiF3∶Eu2 +[8 ,9],and glass ceramicsdoped with rare earth ions[10 ,11]. Of these materials ,BaFBr∶Eu2 +has proven to be the most efficient fromthe point of view of lum…     

Luminescence studies of MBrCl： Eu2＋ （M=Ca, Sr, Ba）

Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photolu-minescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical absorption studies of MBrCl:Eu2+ (M=Ca, Sr, and Ba) revealed that: (1) blue light emission, under the excitation of 300 nm, was observed in all these phosphors; (2) the shape of the emission spectra in CaBrCl:Eu2+ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCl:Eu2+ and BaBrCl:Eu2+ showed no change; and (3) PSL was observed in SrBrCl:Eu2+ and BaBrCI:Eu2+ after X-ray irradiation. Difference absorption spectrum (DAS) in SrBrCl:Eu2+ showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCI:Eu2+ showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser (633 nm) or even semiconductor light-emitting diodes (LED) instead of gas lasers for photostimulation.     

Effect of trivalent rare earth ions doping on the fluorescence properties of electron trapping materials SrS：Eu~（2＋）

Trivalent rare-earth ions (La3+,Pr3+,Nd3+,Sm3+,Gd3+,Tb3+,Dy3+,Ho3+,Er3+,Tm3+,and Yb3+) were investigated as the codoped auxiliary sensitizer for the electron trapping materials SrS:Eu2+ in order to enhance the fluorescence properties.It was found that Sm3+ and Tb3+ had the best photoluminescence stimulated luminescence (PSL) effect among the selected trivalent rare-earth ions.All the SrS:Eu2+ samples doped by different trivalent rare-earth ions could be stimulated by 980 nm laser after being exposed to the conventional sunlight,and they emitted PSL with the peak located at 615 nm.The result also indicated that some co-doped rare earth ions could increase fluorescence intensities of the traditional electron trapping materials SrS:Eu2+.     

Luminescence Properties of Green-Emitting Phosphor (Ba1-x,Srx)2SiO4:Eu2+ for White LEDS

The (Ba1-xSrx)2SiO4∶Eu2 green-emitting phosphors were synthesized by conventional solid-state reaction in a CO-reductive atmosphere, and their luminescent properties were investigated. The XRD data show that the Ba/Sr ratio not only affects the lattice parameters, but also influences the emission peak. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 370 to 470 nm. The emission band is due to the 4f65d1→4f7 transition of the Eu2 ion. With an increase in x, the emission band shifts to longer wavelength and the reason was discussed. The emission spectra exhibit a satisfactory green performance under different excitation wavelength(380, 398, 412, 420, 460 nm). (Ba1-xSrx)2SiO4∶Eu2 is a promising phosphor for green white-lighting-emission diode by ultraviolet chip.     

SrAl_2O_4∶Eu~(2+),Nd~(3+) and Dy~(3+) Long Afterglow Phosphor

Longafterglowphosphorabsorbingenergyfromsolar,lampandotherlightsourcesforashorttimestorestheenergyandexhibitsbrightandlong lastingphosphorescencewhichsuitsthevisualperceptionofthehumaneyewithminimumbrightness 0 32mcd·m- 2 andlastingtimemorethan 8h) .TheSrAl2 O4 ∶Eu2 +,Dy3+phosphorhasbeenknowntobeagreenlongafterglowphosphorwithanemissionpeakat 5 2 0nm[1～ 7] .ThepropertiesofthephosphorwerefurtherexaminedbythegroupofTangMingdaoandMatsuzawaTindetailin 1995and 1996respectively[1,2 ] .Inorde…     

Eu~(2+) Luminescence in BaZnAl_(10)O_(17)∶ Eu Phosphor

Ａｎｉｍｐｏｒｔａｎｔｃｌａｓｓｏｆｆｌｕｏｒｅｓｃｅｎｔｌａｍｐａｎｄｐｌａｓｍａｄｉｓｐｌａｙｐｈｏｓｐｈｏｒｓｉｓｂａｓｅｄｏｎｃｏｍ ｐｏｕｎｄｓｏｆｔｈｅａｌｋａｌｉｅａｒｔｈ ｒａｒｅｅａｒｔｈａｌｕｍｉｎａｔｅｓｙｓｔｅｍｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｈｉｇｈｌｕｍｉｎｅｓｃｅｎｔｅｆｆｉ ｃｉｅｎｃｙａｎｄｓｔａｂｉｌｉｔｙｕｎｄｅｒｕｌｔｒａｖｉｏｌｅｔａｎｄｖａｃｕ ｕｍｕｌｔｒａｖｉｏｌｅｔｌｉｇｈｔｅｘｃｉｔａｔｉｏｎ[1] .Ｅｓｐｅｃｉａｌｌｙ ,ａｌｋａｌｉｎｅｅａｒｔｈｈｅ…     

Study on Luminescence Properties and Crystal-Lattice Environment of Eu~(2 ) in Sr_(4-x)Mg_x Si_3O_8Cl_4∶Eu~(2 ) Phosphor

ChlorosilicatecrystalmaterialM4 Si3O8Cl4 (M =Ba ,Sr ,Ca)isasuitablehostlatticeforluminescencematerials .Adivalenteuropiumactivatedstrontiumchlorosilicatephosphorisakindofgoodblue greenemissionphotoluminescencematerialunderUVexcita tion .Itsluminescencepropertiesandcrystalstructurehavebeenintensivelystudied[1～4 ] .Inthechlorosili catehost ,theluminescenceofEu2 consistsofa4f6 5d1- 4f7(8S7/2 )broad bandemission ,whichbe longstoelectric dipoleallowedtransitionandhasthepropertiesoflargeabso…     

Sol-Gel Synthesis and Luminescent Characteristic of Doped Eu^3 ＋ Silicate-Silica Phosphor

Silicagelphosphorsdopedrareearthionshave attractedgreatattentionofmanyresearchersdueto theseadvantages,suchashighersamplehomogeneity,purityandstable,efficientandenvironmentallyfriend lyphotoluminescencematrixmaterials,whichisless toxicleadtonetconversione…     

A green-yellow emitting β-Sr2SiO4:Eu2+ phosphor for near ultraviolet chip white-light-emitting diode

Sr2SiO4:xEu2 phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu2 phosphor manipulated by Eu2 concentration was studied. The phase transited from β to α′ in Sr2SiO4:xEu2 phosphor with increasing europium concentration. The single β phase was formed as x≤0.005 and changed α′ phase when x>0.01. The emission spectrum of the β-Sr2SiO4:Eu2 phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu2 phosphors were fabricated. The luminous efficiency (15.7 lm/W) was higher than α′-Sr2SiO4:Eu2 phosphor white LED.     

Preparation and Luminescence Properties of the New Long Phosphorescent Phosphors Ba1-xCaxAl2O4∶Eu2+,Dy3+

New long phosphorescent phosphors Ba1-xCaxAl2O4∶Eu2 , Dy3 with tunable color emission were prepared and studied. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is dependent on x, under the excitation of UV. The wavelength of the afterglow increases with the increasing of x until x equals 0.6. The XRD patterns show that the single phase limit in the phosphors is below x value of 0.4. The Thermoluminescence spectra were measured to investigate the traps created by the doping of Dy3 .     

Preparation of Stable CaS∶Eu~(2+), Tm~(3+) Phosphor

Alkalineearthsulfides (AES)havebeenfoundtobeexcellentandversatilephosphor ,andrareearthsasactivatorshavebeenintensivelyinvestigated[1～ 7] .Theyholdpromiseforapplicationsinphoto ,electro ,cathoderay ,fieldemissiondisplaysandluminescencepaints[8,9] .However ,alkalineearthsulfidesasaphos phorhosthavebeenfoundtobelimitedinapplica tion ,duemainlytoitssensitivetomoistureandotheratmosphericcomponents .Theirchemicalstabilityagainstatmosphericcarbondioxideandmoisturecouldbeenhancedthroughthegoodcryst…     

Synthesis and Luminescence Properties of Ba2 MgSi2 O7 :Eu2+ under UV Excitation

Eu2 activated pyrosilicate phosphor were prepared under a reducing atmosphere by solid-state reaction.The crystal structure of Ba2 MgSi2 O7: Eu2 was analyzed by XRD method.The excitation spectrum of Ba2MgSi2 O7; Eu2 is composed of two broad bands centered at about 310 nm and 395 nm respectively.In the emission spectra, the peak wavelength is at about 507 nm under 380 nm UV excitation.It was found that the introduction of Zn2 into Ba2MgSi2O7: Eu2 Can effectively increase its emission intensity without changing the position of emission peak.And the Eu2 and Ce3 codoped pyrosilicate phosphor is the efficient bluish green phosphor under the excitation of long UV light and its emission intensity is stronger than Eu2 doped pyrosilicate phosphor.     

Luminescence Properties of Green-Emitting Phosphor （Ba1- x, Srx ） 2 SiO4 ： EU^2＋ for White LEDS

The （Ba1- x, Srx ） 2 SiO4 ： EU^2＋ green-emitting phosphors were synthesized by conventional solid-state reaction in a CO-reductive atmosphere, and their luminescent properties were investigated. The XRD data show that the Ba/Sr ratio not only affects the lattice parameters, but also influences the emission peak. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 370 to 470 nm. The emission band is due to the 4f^65d^1→4f^7 transition of the Eu^2＋ ion. With an increase in x, the emission band shifts to longer wavelength and the reason was discussed. The emission spectra exhibit a satisfactory green performance under different excitation wavelength（380,398,412,420,460 nm）. （Ba1- x, Srx ） 2 SiO4 ： EU^2＋ is a promising phosphor for green white-lighting-emission diode by ultraviolet chip.     

Optical properties of Eu2+-doped strontium borate glasses containing F- and Li+ ions

In this experiment, strontium borate glasses were prepared using the conventional quenching method in air atmosphere. Optical absorption, photoluminescence excitation and emission spectra, X-ray excited luminescence (XEL), and luminescence decay curve of the as-prepared glasses were investigated at room temperature. The as-prepared glasses had two kinds of Eu ions, i.e., Eu2 and Eu3 . Compared with the reported results of strontium borate glasses, Eu2 luminescence was enhanced in the studied strontium borate glasses coprepared with F- and Li ions. The coexisting of Li or F- in the borate glasses could create more negative defect VSr″ and stabilize Eu2 ions, which might act as donor of electrons;For the F- doping, the new center of B(O, F)4 (or BO3F) and BO2F2 units could be considered to be the distorted (BO4), which were needed as a rigid framework to stabilize the divalent rare earth ions.     

Synthesis of Y2O3 ： EU^3 ＋ Hollow Spheres Using Silica as Templates

The Y2O3 ： EU^3 ＋ hollow spheres were synthesized using the template-mediated method. XRD patterns indicated that the broadened diffraction peaks resulted from nanocrystals in Y2O3 ： EU^3 ＋ shells of hollow spheres. XPS spectra showed that the Y2O3 ： EU^3 ＋ shells were linked with silica cores by a Si-O-Y chemical bond. SEM and TEM observations showed that the size of the SiO2/Y2O3 ： EU^3 ＋ core-shell particle was about 100 nm, and the thickness of the Y2O3 ： EU^3 ＋ hollow sphere was less than 5 nm. The photoluminescence spectra of the SIO2/Y2O3 ： EU^3 ＋ core-shell materials and Y2O3 ： EU^3 ＋ hollow spheres had red luminescent properties, and the broadened emission peaks came from nanocrystals composed of the Y2O3 ： EU^3 ＋ shell.