Study on Luminescence Properties of High-Density Phosphors BiTaO_~(3+) and BiTaO_4

Theparticleenergydetectedbymodernaccelera torsisgettinghigherandhigher ,whichrequiresbetterperformanceforscintillators .Thehigherthedensityofscintillators ,thelargeritslinearattenuationcoeffi cient ,whichcanreducethevolumeofthedetectingcrystalsandcomplicatedandhugeequipmentsoutsideit ,thenreducetheequipmentcostofacceleratorsgreatly .Itsdetectingcrystalconsistsofthousandsup onthousandsofcrystalarrays .Currently ,becauseofitsprominentmeritsofhighdensity (thatis 8.2 9g·cm- 3) ,shortradiationleng…     

Study on Luminescence Properties and Crystal-Lattice Environment of Eu^2＋ in Sr4-xMgxSi3O8Cl4：Eu^2＋ Phosphor

According to the Van Uitert experimental equation, crystal-lattice environment of Eu^2 in the Sr4Si3O8C14 crystal was discussed. By adding Mg^2 to the host lattice, Sr4-xMgxSi3O8C14:Eu^2 was synthesized and the emission peak shifted from blue-green (488nm) to blue-violet (411nm) with the increase of amount of the magnesium which replaced the strontium. By analyzing the spectra of Sr4-xMgxSi3O8C14:Eu^2 the two Eu^2 emission centers were found because of the change of crystal-lattice environment in the host and the crystal structure was obtained by X-ray diffraction data.     

（Zn, Ca） Solid-Solution Behavior and Its Effect on Luminescence Properties in Ca1-x Znx TiO3 ： 0.002Pr^3＋ Phosphors

Nominal composition of Ca1-xZnxTiO3 ： 0. 002Pr^3 ＋ （x = 0. 000 - 0. 200） phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1-xZnxTiO3：0.002Pr^3＋ phosphors. The effect of solid-solution structure formed by substitution between Ca^2 ＋ and Zn^2＋ ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement. Above results are closely related with the structure change within Ca1- xZnxTiO3：0.002Pr^3＋ solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca^2＋ and Zn^2＋ ions has significant effect on the luminescence properties of single phase Ca1-xZnxTiO3：0.002Pr^3＋ phosphors.     

Synthesis and Luminescence Properties of Gd2O3：Eu^3＋ Phosphors

Gd2O3: Eu^3 phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd2O3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd2O3:Eu^3 phosphors. The SEM photographs show that the particles prepared by urea homogeneous precipitation method are all spherical and well-dispersed, and grain morphology can be controlled by different surfactant. XRD and SEM indicate that the particle sizes prepared by sol-gel method are in the range of 5-30 nm, and the grain sizes increase with increasing of heated temperatures. Luminescence spectra indicat that the main emission peaks of all samples are at 610 nm, the intensities are different from samples prepared with different surfactant and the luminescence intensities increase with increasing of annealed temperatures.     

Luminescence Properties of Eu^2 ＋ and Mn^2 ＋ Co-Doped CasMg（SiO4）4Cl2

The green phosphor for white LED, Ca8Mg(SiO4)4C12:Eu^2 , Mn^2 , was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaC12 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu^2 to Mn^2 in Ca8Mg(SiO4)4Cl2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited     

Synthesis and Properties of Tb^3＋-Doped CaxSr1-xWO4

Tb^3 -doped CaxSr1-xWO4 was prepared by solid state reaction and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belongs to tetragonal system, which is consistent with space group 141/α. Lattice parameters in the systems CaxSr1-xWO4 were found to vary linearly with compositions. The emission and excitation spectra were measured. The miscibility, luminescence properties of Tb^3 -doped CaxSr1-xWO4 and energy transfer mechanism were discussed.     

Comparative Study on Photoluminescent Properties of CaGdAlO4：Eu3＋ Phosphors Synthesized with Three Methods

CaGdAlO4 ： Eu^3＋ powder phosphors were prepared using citrate sol-gel （CSG）, haft-dry and half-wet （HDW） and solid state （SS） methods, respectively. X-ray diffraction results confirm the formation of CaGdAlO4：Eu^3＋ at 900 % （CSG）, 1200℃ （HDW） and 1400℃ （SS）, respectively. Field emission scan electron microscopy （FE-SEM） images show that the CaGdAlO4：Eu^3＋ powder prepared by the CSG and HDW method has an elliptical shape and that prepared under the SS method has a flaky shape. Upon excitation with 280 nm UV light, all the CaGdAlO4： Eu^3＋ powders show bright red emission on account of the 4f-4f transitions of the Eu^3＋ ions. Moreover, the size of the phosphor particles and the emission intensity increase with the increase of calcined temperature. At the same calcination temperature of 1400 ℃, the ^5D0→^7F2 emission intensity of the sample prepared by HDW method is the highest. Stark components of the ^5D0→^7FJ emission transitions, both at room temperature and at a low temperature, reveal that the Eu^3＋ ions occupy only one site with non-centrosymmetry in the crystals.     

Preparation and Luminescence Properties of the New Long Phosphorescent Phosphors Ba1-x Cax Al2O4 ： Eu^2＋ , Dy^3＋

New long phosphorescent phosphors Ba1-x CaxAl2O4:Eu^2 , Dy^3 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 Thermolumineseence spectra were measured to investigate the traps created by the doping of Dy^3 .     

Photoluminescent and Electroluminescent Properties of Ligand Emitting y^3＋, La^3＋, Gd^3＋ and Lu^3＋ Complexes

The photolumineseent (PL) and eleetroluminescent (EL) properties of a series of ligand emitting rare earth complexes (including y^3 , La^3 , Gd^3 and Lu^3 ) were systematically studied. These complexes have the same anionic ligand, 1-phenyt-3-methyl-4-isobutyryl-5-pyrazoloneate (PMIP), and three neutral ligands, triphenyl phosphine oxide(TPPO), 2, 2‘-dipyridine (Bipy) and phenanthroline (Phen). Measured with 60 nm thin film of these complexes vaporized in vacuum on quartz substrates, a good regularity in the PL properties was observed. For rational comparison, the same structural EL devices based on these complexes, ITO/PVK (40 nm)/the complex (80 nm)/Mg: Ag (200 nm)/Ag (100 nm), were fabricated. Excluding the exeiplex emission happens, the EL luminance usually increases with the increasing of PL efficiency.     

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.     

Synthesis and Luminescent Properties of Ce^3＋ , Tb^3＋ Co-Doped ZH4B6O13

Green-photoluminescence material Zn4B6O13: Ce^3 , Tb^3 was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters : a0 =0. 7472 nm, V = 0.4172 nm^3, and structural properties are investigated by XRD. The excitation and emission band of Ce^3 ion singledoped in Zn4B6O13 transfer longer spectra 2.38 ～4.94 kk than in other matrices. Emission band of Ce^3 ion better overlaps with the ^7F6→^5G2,^5D1 ,^5H7 absorption band of Tb^3 . It shows that emission of Tb^3 ion is sensitized by Ce^3 . In Zn4B6O13:Ce^3 , Tb^3 , it is due to the energy transfer mechanism, resonance transfer of electric muhipolax interaction of the dipole-dipole between Ce^3 →Ce^3 and Ce^3 →Tb^3 . The color coordinates of ZB4B6O13: x =0.281, y =0.619. The mean diameter of the particles is 0.23μm.     

Thermal Stability and Luminescence Properties of Eu^3＋ and Tb^3＋ Complexes with a Silica Matrix by Sol-Gel Method

Ternary complexes of europium and terbium with benzoic acid and 1, 10-phenanthroline [RE(BA)3phen] (BA=benzoate phen=1,10-phenanthroline) were introduced into a silica matrix by sol-gel method. The thermal stability and luminescence behavior of the complexes in silica gels were studied in comparison with the corresponding solid-state complexes by thermal decomposition, excitation and emission spectra. The thermal stability of the complexes is enhanced in silica gel matrix and the luminescence remaines unchanged.     

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.     

Mechanisms of Fluorescence Quenching of Pr^3＋-Doped PbWO4 Crystal

Fluorescence decay curves of the ^3P0 and ^1D2 manifolds in Pr^3＋ doped PbWO4 crystal were measured at room temperature and fluorescence lifetimes of both manifolds were estimated. Combining with the radiative lifetimes of the manifolds calculated on the basis of the modified J-O theory, the main mechanisms for the fluorescence quenching of the manifolds were analyzed. The multi-phonon relaxation and the cross-relaxation energy transfer are the major reasons for the fluorescence quenching of the ^3P0 and ^1D2 manifolds, respectively. The Inokuti-Hirayama model was used to analyze the fluorescence decay curve of the ^1D2 manifold and the cross-relaxation of dlpole-dipole interaction was confirmed. Consequently, the ^3p0 manifold is more favorable as an upper laser level than the ^1D2 manifold.     

CaTiO3：Pr^3＋的合成及发光性质

报道了稀土离子Ｐｒ＾３＋激活的ＣａＴｉＯ３发光材料的合成方法ＣａＴｉＯ３：Ｐｒ＾３＋位于６１３ｎｍ发射与Ｐｒ＾３＋离子＾１Ｄ２－＾３Ｈ４和光谱发射相一致，讨论了不同合成条件对ＣａＴｉＯ３：Ｐｒ＾３＋发光性持的影响。Ｃ