Fluorescence properties and application of doping complexes Eu1-xLx (TTA)3Phen as light conversion agents

Light conversion agents Eu1-x Lx (TTA)3 Phen (L denotes La3+ , Gd3+ , Y3+ ) complexes were prepared,and the influence of doping ions on fluorescence properties was investigated by elementary analysis, FTIR and fluorescent spectra. The results show that FTIR spectra of Eu1_x Lx (TTA)3 Phen complex system are identical with that of EuTTA3 Phen, which indicates that the complexes Eu1 xLx(TTA)3Phen are similar in structure to Eu (TTA)3Phen. For the above doping elements, co-fluorescence enhancement has the following order: Gd3+ ＞Y3+ ＞La3+ , and the optimum mole fractions of doping elements are 0.4, 0.2 and 0.5 respectively for Gd3+ , Y3+ ,La3+. Among all the complexes, Eu0.6 Gd0.4 (TTA)3 Phen complex has the strongest fluorescent intensity. Applying Eu0.6 Gd0.4 (TTA)3 Phen complex to plastic and printing inks, bright red fluorescence plastic and printing inks are obtained when the content of europium reaches 0.1% (mass fraction).     

Syntheses and applications of Eu（Ⅲ） complexes of 2-thienyltrifluoroacetonate, terephthalic acid and phenanthroline as light conversion agents

A series of europium(Ⅲ) complexes of 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen) were synthesized. The new complexes Eu(TPA)(TTA)Phen and Eu2(TPA)(TTA)4Phen2 were characterized by elemental analysis, IR spectrum, scanning electron microscope and thermal stability analysis. The results show that the thermal stability of the Eu( Ⅲ ) complexes increases in the following order: the mononuclear complex Eu(TTA)3Phen, the binuclear complex Eu2(TPA)(TTA)4Phen2, the chain polynuclear complex Eu(TPA)(TTA)Phen. And the formation of the binuclear/polynuclear structure of the new complexes appears to be responsible for the enhancement of their thermal and optical stability. In addition, The fluorescence excitation spectra of these new complexes show more broad excitation bands than that of the complex Eu(TTA)3Phen corresponding to their formation. The enhancement of Eu3 fluorescence in the new complexes can be observed by the addition of Gd3 . The bright red luminescent plastics can be obtained when the complex EuGd(TPA)(TTA)4Phen2 is added above 0.5% (mass fraction).     

Frequency up-conversion luminescence properties and mechanism of Tm<Superscript>3+</Superscript>/Er<Superscript>3+</Superscript>/Yb<Superscript>3+</Superscript> co-doped oxyfluorogermanate glasses

Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·(1.95-x)GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 (x=0.02,0.05,0.08,0.11,0.14,0.17)in mole percent.Intense blue(476 nm),green(524 and 546 nm)and red(658 nm)emissions which identified from the 1G 4 →3H 6 transition of Tm3+and the(2H 11/2 ,4S 3/2 )→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3+,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white l...     

Combustion synthesis and luminescent properties of CaO: Eu<Superscript>3+</Superscript>, M<Superscript>+</Superscript> (M=Li,Na, K) phosphor

Li⁺, Na⁺, or K⁺ co-doped CaO: Eu³⁺ phosphors were prepared by the combustion synthesis method and characterized by X-ray diffraction (XRD), photoluminescence and photoluminescence excitation (PL-PLE) spectra. The experimental results show that, upon excitation with 250 nm xenon light, the emission spectrum of the CaO: Eu³⁺ consists of 4f-4f emission transitions from the ⁵ D ₀ excited level to the ⁷ F _J (J=1, 2, 3) levels with the mainly electric dipole transition ⁵ D ₀→⁷ F ₂ of Eu³⁺, indicating that the Eu³⁺ occupies a low symmetry. The charge-transfer band (CTB) shows somewhat red shift with the decreasing ionic radii of co-doped alkali metal ions. The PL and PLE intensities are significantly enhanced, especially the strongest intensity of luminescent is CaO: Eu³⁺, Li⁺ phosphor, when alkali metal ions are incorporated. The strongest peak of emission is slightly shifted from 614 to 593 nm, indicating that the Eu³⁺ ion locates in a symmetric position (O _h ) when alkali metal ions are incorporated.     

Phase transition and photoluminescence properties of Eu<Superscript>3+</Superscript>-doped ZnMoO<Subscript>4</Subscript> red phosphors

Eu³⁺-doped ZnMoO₄ with different doping concentrations were synthesized by a hydrothermal method. The effects of Eu³⁺ doping on the phase structure and photoluminescence (PL) properties of ZnMoO₄ were investigated. The result showed that the introduction of Eu3+ could lead to phase transition of ZnMoO₄. With the increase of Eu³⁺ doping amount, β-ZnMoO₄ was transformed to α phase gradually, which led to different photoluminescence performances. The optimized doping concentration of Eu³⁺ was 6 mol% for the highest emission intensity at 615 nm. Its CIE chromaticity coordinates were (0.667, 0.331), which were very close to the values of standard chromaticity (0.67, 0.33) for National Television Standards Committee (NTSC) system. Therefore, Eu³⁺-doped ZnMoO₄ is considered to be a promising red-emitting phosphor for white LED applications.     

Preparation and Upeonversion Lumineseenee ofNanoerystailine Gd2O3： Er^3＋, Yb^3＋

Nanocrystalline Gd1.77Yb0.2Er0.03O3 samples were prepared by combustion and precipitation methods. Structures and upconversion luminescence properties of samples were studied. The results of XRD show that all samples are cubic structure, the average crystallite size could be calculated as 23 nm and 39 nm, respectively. The lattice constants were obtained. The FT-IR spectra were measured to investigate the vibrational feature of the samples. Upconversion luminescence spectra of samples under 980 nm laser excitation were investigated. The strong red emission of samples were observed, and attributed to 4F9/2→4I152 transitions of Er^3＋ ions, the emission intensity for sample synthesized by precipitation method is stronger compared to that of combustion method. The possible upconversion luminescence mechanisms in nanocrystalline Gd1.77Yb0.2Er0.03O3 were discussed.     

Synthesis and luminescence of nano fluorescent powder of Y<Subscript>4</Subscript>Al<Subscript>2</Subscript>O<Subscript>9</Subscript>: Eu<Superscript>3+</Superscript>

Nano fluorescent powder of Y₄Al₂O₉: Eu³⁺ was synthesized by sol-gel method. The XRD shows that the product prepared at 900°C is pure-phase Y₄Al₂O₉: Eu³⁺. The Y₄Al₂O₉ powder is nano-size crystal testified by BF and ED analysis of TEM. The grain diameter of Y₄Al₂O₉ is in the range between 20 and 50nm, and its average is 30 nm. The luminescent spectra show that Eu³⁺ ious occupy two kinds of sites in Y₄Al₂O₉ crystal lattice. One is in the strict inversion center, and the other is in off lying inversion center. When excited with UV light (λ=254nm), Y₄Al₂O₉: Eu³⁺ exhibits an orange emission bond at λ=590 nm due to the⁵D_o→⁷F₁ transition and a red emission band at λ=610 nm due to⁵D_o→⁷F₂ transition. YUAN Xi-ming: Born in 1951 Funded by Key Scientific and Technological Project of Hubei Province (2001 AA102A03)     

Roles of Eu^2＋, Dy^3＋ Ions in Persistent Luminescence of Strontium Aluminates Phosphors

The polycrystalline Eu^2＋ and Dy ^3＋ co-doped strontium aluminates SrAl2O4： Eu^2＋, Dy^3＋ with different compositions were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence were studied and compared. Results show that the doped Eu^2＋ ion in SrAl2O4： Eu^2＋, Dy^3＋ phosphors works as not only the UV-excited luminescent center but also the persistent luminescent center. The doped Dy^3＋ ion can hardly yield any luminescence under UV-excitation, but effectively enhance the persistent luminescence and thermo-luminescence of SrAl2O4： Eu^2＋. Dy^3＋ co-doping can help form electron traps with appropriate depth due to its suitable electro-negativity, and increase the density and depth of electron traps. Based on above observations, a persistent luminescence mechanism, electron transfer model, is proposed and illustrated.     

Fluorescence properties and application of doping complexes Eu1-xLx (TTA)3Phen as light conversion agents

Light conversion agents Eu1-x Lx (TTA)3 Phen (L denotes La3+ , Gd3+ , Y3+ ) complexes were prepared,and the influence of doping ions on fluorescence properties was investigated by elementary analysis, FTIR and fluorescent spectra. The results show that FTIR spectra of Eu1_x Lx (TTA)3 Phen complex system are identical with that of EuTTA3 Phen, which indicates that the complexes Eu1 xLx(TTA)3Phen are similar in structure to Eu (TTA)3Phen. For the above doping elements, co-fluorescence enhancement has the following order: Gd3+ ＞Y3+ ＞La3+ , and the optimum mole fractions of doping elements are 0.4, 0.2 and 0.5 respectively for Gd3+ , Y3+ ,La3+. Among all the complexes, Eu0.6 Gd0.4 (TTA)3 Phen complex has the strongest fluorescent intensity. Applying Eu0.6 Gd0.4 (TTA)3 Phen complex to plastic and printing inks, bright red fluorescence plastic and printing inks are obtained when the content of europium reaches 0.1% (mass fraction).     

Fluorescence properties and application of doping complexes Eu_(l-x)L_x(TTA)_3Phen as light conversion agents

1　INTRODUCTIONRecently ,theinvestigationonlightconversiona gentsmainlycoversorganicluminescentpigments ,in organicluminescentmaterialsandrareearthcomplex esluminescentmaterials[1 4 ] .Organicfluorescentpig mentsforlightconversionagentshavegoodlumines centintensity ,howevertheirstabilityispoor .Inor ganicluminescentmaterialshavegoodstability ,buttheirfluorescentintensityislowandhaspoorcompat ibilitywithresin .Rareearthcomplexesluminescentmaterialshavehighfluorescentintensityandgoodsta bil…     

Interaction of rare earth ions in Sr<Subscript>2</Subscript>MgSi<Subscript>2</Subscript>O<Subscript>7</Subscript>: Eu<Superscript>2+</Superscript>, Dy<Superscript>3+</Superscript> material

To discuss the function of Eu and Dy and their interaction in Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ long afterglow material, the Eu and Dy single doped and their co-doped Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ were prepared. The samples were characterized by X-ray diffraction (XRD), decay curves, photoluminescence (PL), and thermoluminescence (TL). The results indicate that Sr₂MgSi₂O₇: Eu has afterglow properties, and the doping of Eu ion in Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ can lower the depth of traps. Eu ion can not only serve as luminescence center, but also produce traps in the matrix, meanwhile, it also exerts certain influences on the traps produced by Dy in Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺. The Dy ion can not act as luminescence center but relates to the change of the traps in the Sr₂MgSi₂O₇ matrix.     

Fluorescence detection for H<Subscript>2</Subscript>PO<Subscript>4</Subscript><Superscript>-</Superscript> based on carbon dots/Fe<Superscript>3+</Superscript> composite

A novel fluorescent probe for H₂PO₄ ^- was designed and fabricated based on the carbon dots/Fe³⁺ composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe³⁺ composite was obtained by aqueous mixing of carbon dots and FeCl₃, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe³⁺ cations, resulting in the low fluorescence intensity of the carbon dots/Fe³⁺ composite. On the other hand, H₂PO₄ ^- reduced the concentration of Fe³⁺ by chemical reaction and enhanced the fluorescence of the carbon dots/Fe³⁺ composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe³⁺ composite and the concentration of H₂PO₄ ^-, and a fine linearity (R ²=0.997) was found in the range of H₂PO₄ ^- concentration of 0.4-12 mM.     

Preparation of nanometer Nd<Superscript>3+</Superscript>, Y<Superscript>3+</Superscript> co-doped CaF<Subscript>2</Subscript> powder by coprecipitation-azeotropic distillation technique

The synthesis of Nd³⁺, Y³⁺:CaF₂ nanopowder was conducted by azeotropic distillation method, which effectively dehydrated hydrous CaF₂ and prevented forming hard agglomerates. X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning calorimetries-thermalgravimetry (DSC-TG), Fourier transform infrared spectroscopy (FT-IR) and absorption spectroscopy were performed to characterize the powder properties. The experimental results showed that products obtained by azeotropic distillation were single phased, rather monodispersed, successfully prevented the hard agglomerate formation and effectively removed the residual water inside the as-prepared precipitate than that of the direct drying. The absorption spectra showed a wider and stronger absorption bands around 792 nm, which should be profitable for LD pumping.     

Preparation and optical properties of Er<Superscript>3+</Superscript>: Na<Subscript>2</Subscript>O-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript> transparent glass-ceramics

Na₂O-Al₂O₃-SiO₂ glass-ceramics doped with Er³⁺ ions were synthesized by the conventional melt quenching technique at a low melting temperature. The samples were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The results show that the main crystalline phase of glass-ceramics is nepheline.The best heat-treatment process is at 520 °C for 2 h. Because the up-conversion luminescence and near infrared luminescence properties of glass doped with Eu³⁺ are studied in detail.     

Microstructures and fatigue-free properties of the La<Superscript>3+</Superscript> and Nd<Superscript>3+</Superscript> doped Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films prepared by modified sol-gel technique

Ferroelectric Bi_3.25La_0.75Ti₃O₁₂ (BLT) and Bi_3.15Nd_0.85Ti₃O₁₂ (BNT) thin films were fabricated on Pt/TiO₂/SiO₂/Si (100) substrates by a modified sol-gel technique. X-ray diffraction indicated that these films were of single phase with random polycrystalline orientations. The surface morphologies of the films were observed by scanning electron microscope, showing uniform, dense films with grain size of 50–100 nm. Well-saturated hysteresis loops of the films were obtained in metal-ferroelectric-metal type capacitors with Cu top electrodes at an applied voltage of 400 kV/cm, giving the remanent polarization (2P _r) and coercive field (2E _c) values of the films of 25.1 μC/cm² and 203 kV/cm for BLT, and 44.2 μC/cm² and 296 kV/cm for BNT, respectively. Moreover, these capacitors did not show fatigue behaviors after up to 1.75×10¹⁰ switching cycles at the test frequency of 1 MHz, suggesting a fatigue-free character. The influences of the La³⁺ and Nd³⁺ doping on the properties of the films were comparatively discussed. Supported by the National Key Basic Research and Development Program of China (Grant No. 2006CB932305) and the Natural Science Foundation of Hubei Province, China (Grant No. 2004ABA082)     

Crystallization and luminescence properties of Sm<Superscript>3+</Superscript>-doped SrO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript> glass-ceramics

The Sm³⁺-doped SrO-Al₂O₃-SiO₂ (SAS) glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated by DTA, XRD, SEM and luminescence spectroscopy. The results indicate that the crystal phase precipitated in this system is monocelsian (SrAl₂Si₂O₈) and with the increase of nucleation/crystallization temperature, the crystallite increases from 66 % to 79 %. The Sm³⁺-doped SAS glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm under the excitation of 475 nm blue light which can be assigned to the ⁴G_5/2→⁶ H _j/2 (j=5, 7, 9, 11) transitions of Sm³⁺, respectively. Besides, by increasing the crystallization temperature or the concentration of Sm³⁺, the emission lights of the samples located at 565, 605 and 650 nm are intensified significantly. The present results demonstrate that the Sm³⁺-doped SAS glass-ceramics are promising luminescence materials for white LED devices by fine controlling and combining of these three green, orange and red lights in appropriate proportion.     

Luminescent properties of BaO-La2O3-B2O3 glasses with dopant

The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were stud{ed. The emissions spectra of Eu^2 and Eu^3 were observed in BaO-La2O3-B2O3-Eu2O3 glasses.The results show that the broad emission peaks at 430 nm correspond to 5d→4f emission transition of Eu^2 , the sharp emission peaks at 592, 616, 650 and 250 nm correspond to 5^D0→1Fj(j=1--4) emission transition of Eu^3 ,respectively, which indicates that the BaO-La2O3a-B2O3-Eu2O3 glass can convert ultraviolet and green omponents of sunlight into blue and red light so as to increase the intensity of blue and red light, respectively. The luminescent in--tensity of Eu^2 increases with increasing the molar ratio of Tb^3 in BaO-La2O3-B2O3-Eu2O3a-Tb4O3 glasses, whereas the luminescent intensity of Eua^3 decreases. So the luminescent intensity of Eu(Ⅲ,Ⅱ) is influenced by Tb^3 .These phenomena can be explained by electron transfer mechanism; Eu^3 (4f6) Tb^3 (4f^8)→Eu^2 (4f′) Tb^4 (4f′). Taking advantage of the luminescent properties of BaO-La2O3-B2O3-Eu2O3 glasses, light-conversion glass for agriculture can be produced.     

The effect of OH~- groups on the spectroscopic properties of erbium-doped tellurite glasses

With the rapid development of computer networks and other data-transmitting ser-vices, the demand for the increase of transmission capacity of the long distance trans-mission system is urgent. However, the conventional SiO2-based EDFA is limited for its small bandwidth. The Er3+-doped tellurite glass exhibits a larger stimulated-emission cross section and a broader emission bandwidth at the third communication window (1.55 μm) than that of silicate, phosphate, and germanate glasses, which c…     

Separation of red (Y2O3:Eu3+), blue (BaMgAl10O17:Eu2+) and green (CeMgAl10O17:Tb3) rare earth phosphors by liquid/liquid extraction

A novel process for separation of red (Y₂O₃:Eu³⁺), blue(BaMgAl₁₀O₁₇:Eu²⁺) and green (CeMgAl₁₀O₁₇:Tb³) rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone (TTA) dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant (PST). Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows: red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%. Funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (ROCS, SEM [2005] No. 383)     

Chlorofluorocarbons and<Superscript>3</Superscript>H/<Superscript>3</Superscript>He in groundwater

Based on the CFC concentration, the fraction of young groundwater in a mixture with old groundwater can be defined if the age of the young component is known. The authors argued that the ratio of [³He_t]/[³H_t] in a young water is independent of its mixing with old waters. Hence, the³H?³He can be used to determine age of the young groundwater, though mixing with old groundwater may occur. CFC concentrations are susceptible to change by mixing of young and old water. The combination of CFCs and tritium/helium can provide confidential apparent age of the young groundwater and fraction of the young water in the mixture with old groundwater.