Spectra and long-lasting properties of Sm3+-doped yttrium oxysulfide phosphor

We reported, for the first time to the best of our knowledge, the Sm3+ -doped yttriurn oxysulfide phosphors has reddish orange long-lasting phosphorescence. The phosphor show prominent luminescence in reddish orange due to the electronic transitions of (4)G(5/2) --> H-6(J) (J = 5/2, 7/2, 9/2), the afterglow color of this type of phosphors is a mixture of the three above mentioned electronic transition emissions and have a little different when the concentration of the Sm3+ dopant changes. Synthesis procedure of the Sm3+-yttrium oxysulfide reddish orange phosphor through the flux fusion method with binary flux compositions was presented. The synthesized phosphors were analyzed using X-ray diffraction (XRD) to interpret the structural characterization. The XRD analysis result reveal that the Y2O2S:Sm3+ phosphor synthesized with a binary flux composition containing (S and Na2CO3 at a ratio of 1: 1 at 30 wt.% of total raw material) at 1050degreesC for 3 h was in single-phase. Luminescence properties of the Y2O2S:Sm3+ long-lasting phosphor was analyzed by measuring the excitation spectra, emission spectra and afterglow decay curve. The mechanism of the strong afterglow from Y2O2S:Sm3+ was also discussed in this paper.

Long-lasting properties of rare earth-doped Y2O2S phosphors

The aim of this presentation is to report a new result of afterglow materials. The Y2OS: Ln(3+) (Ln = Sm, Tm) phosphors show bright reddish orange and orange-yellow colors when excited by UV or visible light. The main spectroscopic characterizations of Sin(3+) and Tin(3+) in yttrium oxysulfide and their long-lasting phosphorescence were measured and discussed in this presentation. Their long-lasting phosphorescence can be seen by the naked eyes clearly for about one hour in the dark room after the Irradiation light sources were removed. XRD and photoluminescence (PL) spectra as well as the luminance decay were used to characterize these long-lasting phosphorescence phosphors. The results of XRD indicate that the products synthesized through the flux fusion method tinder 1050 degreesC, for 6 It have a good crystallization without any detectable amount of impurity phase. Both the PL spectra and luminance decay results reveal that these phosphors have efficient luminescent and good long-lasting properties. We believe that the experimental data gathered in our present work will be. useful in finding some new long-lasting phosphors with different colors.

Luminescent sol-gel thin films based on europium-substituted heteropolytungstates

Polyester thin films containing europium-substituted heteropolytungstate were obtained on quartz plate by the sol-gel method. The films exhibited the characteristic emission bands of the europium ion. The red to orange intensity ratio (R:O) of Eu3+ in the films increased as compared to the corresponding heteropolytungstate solids. The fluorescence lifetime of europium is shorter in the thin film than in the heteropolytungstate solid. The results indicated that the formation of europium-substituted heteropolytungstate/polyester thin film has great effect on the luminescence of europium- substituted heteropolytungstate.

White electroluminescence from polyfluorene chemically doped with 1,8-napthalimide moieties

An efficient white light-emitting polymer was developed with blue polyfluorene (PFO) chemically doped with orange fluorescent 1, 8-naphthalimide moieties. The emission spectrum can be easily tuned by varying the content of 1, 8-naphthalimide moieties. A white polymeric light-emitting diode (WPLED) with a structure of indium tin oxide (ITO)/the complex of (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT)/polymer/Ca/Al showed a current efficiency of 5.3 cd/A and a power efficiency of 2.8 Lm/W at 6 V with the Commission Internationale de L'Eclairage (CIE) coordinates at (0.25,0.35). Moreover, the WPLED from the copolymer showed a very stable white light emission at different driving voltage and brightness. The CIE coordinates of the WPLED were (0.25, 0.35), (0.26, O.36), and (0.26, 0.36) under driving voltages of 6, 8, and 10 V, corresponding to the brightness of 82, 3555, and 7530 cd/m(2), respectively. This approach for realization of white light emission is promising over the polymer blending system in terms of both efficiency and color stability.

Highly efficient iridium(III) complexes with diphenylquinoline ligands for organic light-emitting diodes: Synthesis and effect of fluorinated substitutes on electrochemistry, photophysics and electroluminescence

A series of novel cyclometalated iridium(III) complexes bearing 2,4-diphenylquinoline ligands with fluorinated substituent were prepared and characterized by elemental analysis, NMR and mass spectroscopy. The cyclic voltammetry, absorption, emission and electroluminescent properties of these complexes were systematically investigated. Electrochemical studies showed that the oxidation of the fluorinated complexes occurred at more positive potentials (in the range 0.57-0.69 V) than the unfluorinated complex 1 (0.42 V). In view of the energy level, the lowering of the LUMO by fluorination is significantly less than that of the HOMO. The weak and low energies absorption bands in the range of 300-600 nm are well resolved, likely associated with MLCT and (3)pi-pi* transitions. These complexes show strong orange red emission both in the solution and solid state. The emission maxima of the fluorinated complexes showed blue shift by 9, 24 and 15 nm for 2, 3 and 4, respectively, with respect to the unfluorinated analogous 1. Multilayered organic light-emitting diodes (OLEDs) were fabricated by using the complexes as dopant materials. Significantly higher performance and lower turn-on voltage were achieved using the fluorinated complexes as the emitter than that using the unfluorinated counterpart 1 under the same doping level.

Highly efficient phosphorescent bis-cyclometalated iridium complexes based on quinoline ligands

The synthesis and electrochemical and photophysical study of a series of bis-cyclometalated iridium(III) complexes based on quinoline ligands have been carried out. These complexes are found to emit red-orange to deep red phosphorescence with high quantum yield and short lifetime. The red organic light-emitting diodes (OLEDs) with the external quantum efficiency up to 11.3% were demonstrated. Slow decay of efficiency with increasing current density was observed. These indicate that quinoline-based iridium complexes are promising candidates for efficient red emitters.

Luminescence properties of rare earth-polyoxometalate thin film deposited by sol-gel process

The rare earth (Eu3+, Dy3+)-polyoxometalate thin films were fabricated on quartz plate by the sol-gel method. The thin films were demonstrated by the luminescence spectra. The thin films exhibit the characteristic emission bands of the rare-earth ions. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ and the red to orange ratio (R:O) of Eu3+ in the films are different from that of the corresponding solids. Furthermore, the thin films present shorter fluorescence lifetime than the pure complexes. The reasons that were responsible for these results were also discussed.

Preparation of Y3Al5O12 : Eu phosphors by citric-gel method and their luminescent properties

By using metal nitrates as starting materials and citric acid as complexing agent, Y3Al5O12 (YAG) and Y3Al5O12:Eu (1 mol%) (YAG:Eu) powder phosphors were prepared by a citrate-gel method. The formation process of YAG and YAG:Eu were investigated by means of XRD, TG-DTA and FT-IR spectra. The purified crystalline phases of YAG and YAG:Eu were obtained at 800 degreesC. The crystalline YAG:Eu phosphors showed an orange-red emission with D-5(0)-F-7(1) (591 nm) as the most prominent group, whose intensity was dependent on the pH value of the starting solution, citric acid content and firing temperature. It has been found that the suitable pH and citric acid/metal ratio are 3 and 2 for obtaining the highest emission intensity, respectively. The emission intensity increases steadily with increasing the annealing temperature from 800 to 1200 degreesC, and nearly remains constant after 1200 degreesC. Furthermore, great differences were observed for the lifetimes and the charge transfer band of Eu3+ in crystalline and amorphous states of YAG.

A STUDY ON THE LUMINESCENCE PROPERTIES OF EU3+ AND DY3+ IN M(2)RE(8)(SIO4)(6)O-2 (M=MG, CA RE=Y, GD, LA)

In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.

COMPARATIVE-STUDY OF CA4Y6(SIO4)(6)O-A PHOSPHORS PREPARED BY SOL-GEL AND DRY METHODS (A=PB2+,EU3+, TB3+,DY3+)

Ca4Y6(SiO4)(6)O:A (A = Pb2+, Eu3+, Tb3+, Dy3+) phosphors have been prepared by two methods: the sol-gel method and the conventional dry method. The crystallization processes and the luminescence characteristics of the phosphors were studied, The sol-gel method features low-temperature formation of the phosphor, leading to successful preparation of Pb2+-activated phosphors which could not be prepared by the dry method at high temperature. The (4f)(8-)(4f)(7)(5d)(1) absorption band of Tb3+ and the charge-transfer (CT) band of Eu3+ have higher energies and narrower half-widths in the sol-gel-derived phosphors than in the phosphors prepared by the dry method, respectively. The Tb3+ and Dy3+ ions show stronger emission in the former than in the latter. Both the yellow-to-blue intensity ratio (Y:B) of Dy3+ and the red-to-orange intensity ratio (R:O) of Eu3+ in the sol-gel-derived phosphors are smaller than those for the phosphors derived by the dry method.

INVESTIGATION ON THE LUMINESCENCE PROPERTIES OF DY-3+ AND EU-3+ IN ALKALINE-EARTH BORATES

In this paper, the yellow-to-blue intensity ratio of Dy3+ (Y/B) and the red-to-orange intensity ratio of Eu3+ (R/O) were studied in relation to the compositions and structures of alkaline-earth borates. The dependence of the energy of the Eu3+ charge-transfer band (CTB) and of the emission intensity of Dy3+ on the alkaline-earth ions and the boron content of the hosts is discussed.

A NOVEL SHELL COLOR VARIANT OF THE PACIFIC ABALONE HALIOTIS DISCUS HANNAI INO SUBJECT TO GENETIC CONTROL AND DIETARY INFLUENCE

Molluscan shells may display a variety of colors, which formation, inheritance, and evolutionary significance are not Well understood. Here we report a new variant of the Pacific abalone Haliotis discus hannai that displays a novel orange shell coloration (O-type) that is clearly distinguishable from the Wild green-shelled abalone (G-type). Controlled mating experiments between O- and G-type abalones demonstrated apparent Mendelian segregations (1:1 or 3:1) in shell colors in F-2 families, which support the notion that the O- and G-types are under strict genetic control at a single locus With a recessive o (for orange shell) allele and a dominant G (for green shell) allele. Feeding with different diets caused modifications of shell color within each genotype, ranging from orange to yellow for O-type and green to dark-brown for the G-type, without affecting the distinction between genotypes. A previously described bluish-purple (B-type) shell color was found in one of the putative oo X oG crosses, suggesting that the B-type may be it recessive allele belonging to the same locus. The new O-type variant had no effect on the growth of Pacific abalone on the early seed-stage. This Study demonstrates that shell color in Pacific abalone is subject to genetic control as well as dietary modification, and the latter probably offers selective advantages in camouflage and predator avoidance.

Wangia profunda gen. nov., sp nov., a novel marine bacterium of the family Flavobacteriaceae isolated from southern Okinawa Trough deep-sea sediment

An orange-pigmented, Gram-negative, nonmotile, strictly aerobic and oxidase- and catalase-positive bacterium (SM-A87(T)) was isolated from the deep-sea sediment of the southern Okinawa Trough area. The main fatty acids were i15 : 0, i17 : 0 3OH, i15 : 1 G, i17 : 1 omega 9c, 15 : 0, i15 : 0 3OH and summed feature 3 (comprising i-15 : 0 2OH and/or 16 : 1 omega 7c). MK-6 was the predominant respiratory quinone. DNA G+C content was 35.8 mol%. Flexirubin-type pigments were absent. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain SM-A87(T) formed a distinct lineage within the family Flavobacteriaceae, with < 93% sequence similarity to the nearest strain of genus Salegentibacter. Moreover, strain SM-A87(T) could be distinguished from the nearest phylogenetic neighbors by a number of chemotaxonomic and phenotypic properties. On the basis of polyphasic analyses, it is proposed that strain SM-A87(T) be classified in a novel genus and a new species in the family Flavobacteriaceae, designated Wangia profunda gen. nov., sp. nov. The type strain is SM-A87(T) (CCTCC AB 206139(T)=DSM 18752).