Preparation, patterning and luminescent properties of oxyapatite La-9.33(SiO6)(4)O-2 : A (A = Eu3+, Tb3+, Ce3+) phosphor films by sol-gel soft lithography

Silicate oxyapatite La-9.33 (SiO6)(4)O-2:A (A = Eu3+, Tb3+ and/or Ce3+) phosphor films and their patterning were fabricated by a sol-gel process combined with soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, atomic force microscopy, optical microscopy and photoluminescence spectra, as well as lifetimes, were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 800degreesC and the crystallinity increased with the increase in annealing temperatures. Transparent nonpatterned phosphor films were uniform and crack-free, which mainly consisted of rodlike grains with a size between 150 and 210 nm. Patterned thin films with different bandwidths (20, 50 mum) were obtained by the micromoulding in capillaries technique. The doped rare earth ions (Eu3+, Tb3+ and Ce3+) showed their characteristic emission in crystalline La-9.33(SiO6)(4)O-2 phosphor films, i.e. Eu3+ D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4), Tb3+ D-5(3,4)-F-7(J) (J = 3, 4, 5, 6) and Ce3+ 5d (D-2)-4f (F-2(2/5), F-2(2/7)) emissions, respectively. Both the lifetimes and PL intensity of the Eu3+, Tb3+ ions increased with increasing annealing temperature from 800 to 1100 degreesC, and the optimum concentrations for Eu3+, Tb3+ were determined to be 9 and 7 mol% of La3+ in La-9.33(SiO6)(4)O-2 films, respectively. An energy transfer from Ce3+ to Tb3+ was observed in the La-9.33(SiO6)(4)O-2:Ce, Tb phosphor films, and the energy transfer efficiency was estimated as a function of Tb3+ concentration.

Luminescent properties of rare-earth-doped CaWO4 phosphor films prepared by the Pechini sol-gel process

CaWO4 phosphor films doped with rare-earth ions (Eu3+, Dy-,(3+) Sm3+, Er3+) were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, atomic force microscopy, and photoluminescence spectra, as well as lifetimes, were used to characterize the resulting powders and films. The results of the XRD analysis indicated that the films began to crystallize at 400degreesC and that the crystallinity increased with elevation of the annealing temperature. The doped rare-earth ions showed their characteristic emissions in crystalline CaWO4 phosphor films due to energy transfer from WO42- groups to them. Both the lifetimes and PL intensities of the doped rare-earth ions increased with increasing annealing temperature, from 500 to 900degreesC, and the optimum concentrations for Eu3+, Dy3+, Sm3+, Er3+ were determined as 30, 1.5, 1.5, 0.5 at.% of Ca2+ in CaWO4 films annealed at 900degreesC, respectively.

Luminescence properties of RP1-xVxO4: A (R=Y, Gd, La; A=Sm3+Er3+ x=0, 0.5, 1) thin films prepared by pechini sol-gel process

Thin film phosphors with compositions of RP1-xVxO4: A (R = Y, Gd, La; A = Sm3+, Et3+; x = 0, 0.5, 1) have been prepared by a Pechini sol-gel process. X-Ray diffraction, atomic force microscopy (AFM), photoluminescence excitation and emission spectra were utilized to characterize the thin film phosphors. The results of XRD showed that a solid solution formed in YVxP1-xO4: A film series from x = 0 to x = 1 with zircon structure, which also held for GdVO4: A film. However, LaVO4: A film crystallized with a different structure, monazite. AFM study revealed that the phosphor films consisted of homogeneous particles ranging from 90 to 400 nm depending on the compositions. Upon short ultraviolet excitation, the films exhibit the characteristic Sm(3+ 4)G(5/2)-H-6(J) (J=5/2, 7/2, 9/2) emission in the red region and Er3+ H-2(11/2), S-4(3/2)-I-4(15/2) emission in the green region, respectively With the increase of x values in YVxP1-xO4: SM3+ (Er3+) films, the emission intensity Of SM3+ (Er3+) increases due to the increase of energy transfer probability from VO43- to Sm3+ (Er3+). Due to the structural effects, the Sm3+ (Er3+) shows similar spectral properties in YVO4 and GdVO4 films, which are much different from those in LaVO4 film.

Patterning and luminescent properties of nanocrystallineY(2)O(3): Eu3+ phosphor films by sol-gel soft lithography

Nanocrystalline Y2O3:Eu3+ phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with a soft lithography. X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM), optical microscopy, UV/vis transmission and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 500 degreesC and the crystallinity increased with the elevation of annealing temperatures. Uniform and crack free non-patterned phosphor films were obtained, which mainly consisted of grains with an average size of 70 nm. Using micro-molding in capillaries technique, we obtained homogeneous and defects-free patterned gel and crystalline phosphor films with different stripe widths (5, 10, 20 and 50 mum). Significant shrinkage (50%) was observed in the patterned films during the heat treatment process. The doped Eu3+ showed its characteristic emission in crystalline Y2O3 phosphor films due to an efficient energy transfer from Y2O3 host to them. Both the lifetimes and PL intensity of the Eu3+ increased with increasing the annealing temperature from 500 to 900 degreesC, and the optimum concentrations for Eu3+ were determined to be 5 mol%.

Morphology control and luminescence properties of YAG : Eu phosphors prepared by spray pyrolysis

Starting from nitrate aqueous solutions with citric acid and polyethylene glycol (PEG) as additives, Y3Al5O12:Eu (YAG:Eu) phosphors were prepared by a two-step spray pyrolysis (SP) method. The obtained YAG:Eu phosphor particles have spherical shape, submicron size and smooth surface. The effects of process conditions of the spray pyrolysis on the crystallinity, morphology and luminescence properties of phosphor particles were investigated. The emission intensity of the phosphors increased with increasing of sintering temperature and solution concentration due to the increase of the crystallinity and particles size, respectively. Adequate amount of PEG was necessary for obtaining spherical particles, and the optimum emission intensity could be obtained when the concentration of PEG was 0.10 g/ml in the precursor solution. Compared with the YAG:Eu phosphor prepared by citrate-gel (CG) method with non-spherical morphology, spherical YAG:Eu phosphor particles showed a higher emission intensity.

Study on the reduction of Eu3+ -> Eu2+ in Sr4Al14O25: Eu prepared in air atmosphere

Compounds of Sr4Al14O15: Eu were prepared in air atmosphere by high temperature solid state reaction. The reduction of Eu3+--> Eu2+ was firstly observed in the aluminate phosphor of Sr4Al14O25: Eu synthesized in air condition. This made aluminate a new family and Sr4Al14O25 a new member of compounds in which Eu3+ ion could be reduced to Eu2+ form when fired in air atmosphere. The reduction of Eu3+ --> Eu2+ in Sr4Al14O25: Eu was explained by means of a charge compensation model. Experiments based on the model were designed and carried out, and the results supported this model.

一种新的橙红色长余辉荧光材料Y_2O_2S∶Sm~(3+)

铜激活的硫化锌 (Zn S∶ Cu)和铕激活的硫化钙 (Ca S∶ Eu)是最早获得应用的蓝色和红色长余辉材料 .随后 ,相继发现了铝酸盐体系和硅酸盐体系两大类长余辉荧光材料 [1～ 3 ] .这两类长余辉荧光材料在发光亮度、余辉时间、稳定性方面都较前述硫化物系列长余辉荧光材料有很大提高 ,从而具有非常广阔的应用前景和应用范围 [4～ 6] .但这两类长余辉荧光材料的发光颜色一般为蓝紫、蓝或黄绿 ,没有红色发光现象 .随着研究的深入 ,人们发现了稀土元素激活的碱土钛酸盐红色长余辉荧光材料 ,这种荧光材料在发光亮度及余辉上都有明显的提高 [7,8] ,而且解决了硫化物不稳定的缺点 .近年来才发展起来的以碱土金属氧化物为发光基质 ,以 Eu3 + 为激活剂的红色长余辉荧光材料进一步提高了余辉亮度及时间 [9] .传统碱土硫化物类磷光体有较宽的激发谱带 ,可在不同的光源下激发 .但它的稳定性较差 ,必须进行工艺后处理才能得到应用 .其它几类磷光体的激发光源谱带较窄 ,仅限于紫外光源 ,因此使其应用范围受到限制 .目前已报道的各种长余辉红色荧光材料在余辉时间方面有较大的差异 ,从十几分钟到几百分钟不等 ,各类红色磷光...

稀土Sm对于Cu/Zr基合成醇催化剂的改性作用

中国科学院山西煤炭化学研究所

Local structure and valences of samariurn in SrB4O7 : Sm and SrB6O10 : Sm prepared in-air

The coordination numbers for the samarium atoms and the Sm-O bond distances in SrB4O7:Sm and SrB6O10:Sm prepared in air were determined by means of Sm-L-3 edge EXAFS. The coordination. was found to be nine-folded for both these hosts and the bond distance was 2.40-2.42 Angstrom in SrB4O7:Sm and 2.42-2.44 Angstrom in SrB6O10:Sm. For SrB4O7:Sm the coordination number is coincident with that of the strontium. atoms suggesting the substitution of the samarium atoms at the strontium sites. The coordination number of the strontium atoms in SrB6O10 was also suggested to be nine assuming the same type of substitution. The valences of samarium were determined from the luminescent spectra. Both divalent and trivalent ions were present in both SrB4O7:Sm and SrB6O10:Sm, while the fraction of Sm2+ was higher in the former than in the latter. This difference has been assigned to the difference in rigidity between the B-O networks in these structures.

Synthesis-dependent luminescence properties of Y3Al5O12 : Re3+ (Re=Ce, Sm, Tb) phosphors

By using metal nitrates and oxides as the starting materials, Y2Al5O12 (YAG) and YAG:Re3+ (Re = Ce, Sm, Th) powder phosphors were prepared by solid-state (SS), coprecipitation (CP) and citrate gel (CG) methods. The resulting YAG and YAG-based phosphors were characterized by XRD, FT-IR, SEM and photoluminescent excitation and emission spectra. The purified crystalline phases of YAG were obtained at 800 degreesC (CG) and 900 degreesC (CP, SS). At an identical annealing temperature and doping concentration, the doped rare-earth ions showed the stronger emission intensity in the CP- and SS-derived phosphors than the CG-derived YAG phosphors. The poor emission intensity for the CG-derived phosphors is mainly caused by the contamination of carbon impurities from citric acid in the starting materials.

Sol-gel derived silicate oxyapatite phosphor films doped with rare earth ions

Rare-earth (Eu3+, Tb3+)-doped Ca2Y8(SiO4)(6)O-2 luminescent thin films were dip-coated on silicon and quartz glass substrates through a sol-gel route. X-ray diffraction (XRD), scanning electron microscopy (SEM) and luminescence excitation and emission spectra as well as luminescence decays were used to characterize the resultant films. The results of XRD reveal that these films remain amorphous below 700 degreesC, begin to crystallize at 800 degreesC, and crystallize completely around 1000 degreesC with an oxyapatite structure. The grain structure of the film can be seen clearly from SEM micrographs, where particles with various shape and average size of 250 nm can be resolved. The Eu3+ and Tb3+ ions show their characteristic red (D-5(0)-F-7(2)) and green (D-5(4)-F-7(5)) emission in the films with a quenching concentration of 10 and 6 mol% (of Y3+), respectively. The lifetime of Eu-3divided by increases with the heat treatment temperature front 700 to 1100 degreesC.

Crystal structure of a luminescent complex Sm(HTH)(3)Phen

The crystal structure of Sm(HTH)(3)Phen [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione, Phen: 1,10-Phenanthroline] has been determined by single crystal X-ray diffraction and the coordination geometry of Sm atom is a dodecahedron. The complex can give the characteristic luminescence of Sm3+ upon UV excitation.

Syntheses and crystal structures of bis(tetrahydrofurfurylindenyl) lanthanocene chlorides (C4H7OCH2C9H6)(2)LnCl (Ln = Nd, Sm, Dy, Ho, Er, Yb)

Reaction of anhydrous lanthanide trichlorides with tetrahydrofurfuryl indenyl lithium in THF afforded bis(tetrahydrofurfurylindenyl) lanthanocene chlorides complexes (C4H7OCH2C9H6)(2) LnCl, Ln = Nd (1), Sm (2), Dy (3), Ho (4), Er (5), Yb (6). The X-ray crystallographic structures of all the six complexes were determined and these indicate that they are unsolvated nine-coordinate monomeric complexes with a trans arrangement of both the sidearm and indenyl rings in the solid state. They belong to the same crystal system (orthorhombic) and space group (P2(1)2(1)2(1)) with the same structure. Especially, they are more stable to air and moisture than the corresponding unsubstituted indenyl lanthanide complexes.

Fabrication, patterning, and optical properties of nanocrystalline YVO4 : A (A = Eu3+, Dy3+, Sm3+, Er3+) phosphor films via sol-gel soft lithography

Nanocrystalline YVO4:A (A = Eu3+, Dy3+, Sm3+, Er3+) phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM) and optical microscopy, UV/vis transmission and absorption spectra, photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 400 degreesC and the crystallinity increased with the increase of annealing temperatures. Transparent nonpatterned phosphor films were uniform and crack-free, which mainly consisted of grains with an average size of 90 nm. Patterned gel and crystalline phosphor film bands with different widths (5-60 mum) were obtained. Significant shrinkage and a few defects were observed in the patterned films during the heat treatment process. The doped rare earth ions (A) showed their characteristic emission in crystalline YVO4 phosphor films because of an efficient energy transfer from vanadate groups to them. The Sm3+ and Er3+ ions also showed upconversion luminescence in a YVO4 film host. Both the lifetimes and PL intensity of the rare earth ions increased with increasing annealing temperature from 400 to 800 degreesC, and the optimum concentration for Eu3+ was determined to be 7 mol % and those for Dy3+, Sm3-, and Er3+ were 2 Mol % of Y3- in YVO4 films, respectively.

Sol-gel deposition and luminescent properties of oxyapatite Ca-2(Y,Gd)(8)(SiO4)(6)O-2 phosphor films doped with rare earth and lead ions

Rare-earth and lead ions (Eu3+, Tb3+, Dy3+, Pb2+) doped Ca2Y8 (SiO4)(6)O-2 and Ca2Gd8(SiO4)(6)O-2 thin films have been dip- coated on silicon and quartz glass substrates through the sol- gel route. X- Ray diffraction (XRD), TG- DTA, scanning electron microscopy (SEM), atomic force microscopy (AFM), FT- IR and luminescence excitation and emission spectra as well as luminescence decays were used to characterize the resulting films. The results of XRD reveal that these films remain amorphous below 700 degreesC, begin to crystallize at 800 degreesC and crystallize completely around 1000 degreesC with an oxyapatite structure. The grain structure of the film can be seen clearly from SEM and AFM micrographs, where particles with various shapes and average size of 250 nm can be resolved. Eu3+ and Tb3+ show their characteristic red (D-5(0)-F-7(2)) and green (D-5(4) - F-7(5)) emission in the films with a quenching concentration of 10 and 6 mol% (of Y3+), respectively. The lifetime and emission intensity of Eu3+ increase with the temperature treatment from 700 to 1100 degreesC, while those of Tb3+ show a maximum at 800 degreesC. Energy transfer phenomena have been observed by activating the oxyapatite film host- lattice Ca2Gd8(SiO4)(6)O-2 with Tb3+ (Dy3+). In addition, Pb2+ can sensitize the Gd3+ sublattice in Ca2Gd8(SiO4)(6)O-2.