Hydrothermal synthesis and spectral properties of the Eu doped KZnF3

The polycrystals of KZnF3 : Eu have been synthesized by hydrothermal method at 220 degreesC, The product was characterized by XRD, XPS and SEM. The emission and excitation spectra of europium ion were measured. The existence of Eu2+ ion was confirmed by ESR and spectroscopy. The sites were possibly occupied by Eu2+ ions, charge compensation in this crystal were also discussed.

Preparation and luminescence properties of ormosil material doped with Eu(TTA)(3)phen complex

The europium complex, Eu(TTA)(3)phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) was successfully doped into organically modified silicate (ormosil) matrix-SiO2/(VTMOS+PMMA) (VTMOS = vinyltrimethoxysilane, PMMA = polymethylmethacrylate) via sol-gel process, and the luminescence properties of the resultant ormosil composite phosphors [ormosil: Eu(TTA)(3)phen were investigated compared with those of the pure Eu(TTA)(3)phen complex powder. The ormosil composite materials incorporated with Eu(TTA)(3)phen show the characteristic red emission of Eu3+ ion. The Eu3+ possesses fewer emission lines and longer lifetime in the hybrid phosphor than in the pure Eu(TTA)(3)phen complex. This has been explained from the viewpoint of the surrounding environment where the Eu3+ ion lies. (C) 2000 Elsevier Science B.V. All rights reserved.

Preparation and luminescence properties of sol-gel hybrid materials incorporated with europium complexes

Microporous silica gel has been prepared by the sol-gel method utilizing the hydrolysis and polycondensation of tetraethylorthosilicate (TEOS). The gel has been doped with the luminescent ternary europium complex Eu(TTA)(3). phen: where HTTA = 1-(2-thenoyl)-3,3,3-trifluoracetone and phen = 1,10-phenanthroline. By contrast to the weak f-f electron absorption bands of Eu3+, the complex organic ligand exhibits intense near ultraviolet absorption. Energy transfer from the ligand to Eu3+ enables the production of efficient, sharp visible luminescence from this material. Utilizing the polymerization of methyl methacrylate or ethyl methacrylate, the inorganic/polymer hybrid materials containing Eu(TTA)(3). phen have also been obtained. SEM micrographs show uniformly dispersed particles in the nanometre range. The characteristic luminescence spectral features of europium ions are present in the emission spectra of the hybrid material doped with Eu(TTA)3 phen. (C) 2000 Kluwer Academic Publishers.

Luminescent properties of organic-inorganic hybrid monoliths containing rare-earth complexes

Transparent organic-inorganic hybrid monoliths containing rare-earth complexes (Eu(TTA)(3)Phen, Tb(Sal)(3)) were prepared via the sol-gel technique. It could be observed by transmission electron microscopy that the fluorescent particles are distributed in the matrix at the microscopic level. The matrix is composed of organic-inorganic semiinterpenetrating networks, i.e., PHEMA-SiO2 system. The fluorescence emission spectra of samples are similar to those from corresponding powdered Eu(III) and Tb(III) complexes, and the half-widths of the strongest bands are less than 10 nm, which indicates that the monolith exhibits high fluorescence intensity and color purity. Furthermore, the fluorescence spectra exhibit no obvious change with decreasing nanoparticle size of the rare-earth complex. The fluorescence lifetimes of samples are longer than pure Eu(III), Tb(III) complexes, respectively. Samples irradiated with an UV lamp (365 nm) are still transparent but become bright red and green in color due to fluorescence of Eu(III) and Tb(III) complexes. (C) 2000 Elsevier Science B.V. All rights reserved.

Luminescent properties of Langmuir-Blodgett films of europium bisphthalocyanine

Eu(III)-octa-4-(tetrahydrofurfuroxy) phthalocyanine (EuPc2') was synthesied and characterized by elementary analysis, IR, MS, UV-vis spectra. EuPc2' has good film-forming ability from determination of isotherm of pi-A. The complex LB film was formed by depositing of EuPc2' on a quartz slide with the LB techniques of the Z-type, The luminescent properties of pure and doped LS films were determined. The results showed that pure films have good luminescent properties, the thicker the LB films, the stronger the fluorescent intensity. The films doped with o-phenanthroline (abbreviated as phen) made the relative intensity of fluorescent emission behavior enhance in comparison to that of pure LB film, But the amount of phen may be not too much. Our results showed that EuPc2':phen = 1: 10 (molar ratio) has the best fluorescent behavior. The electronic spectroscopic characterization of the LB films is also given.

Synthesis and electroluminescent properties of a novel terbium complex

A new carboxylic acid ligand (o-amino-4-hexadecane benzoic acid, AHBA) and a corresponding terbium complex (Tb(AHB)(3)) were synthesized and characterized. A multilayer electroluminescent device with poly(N-vinylcarbazole) (PVK), 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) and the terbium complex as emissive layer was fabricated: glass substrate/ITO/PPV/PVK:-To(AHB)(3):PBD/Alq(3)/Al. The photoluminescence (PL) and electroluminescence (EL) spectra were discussed. This EL cell exhibited characteristic emission of terbium ions with a maximum luminance of 35 cd/m(2) at 20 V. (C) 2000 Elsevier Science S.A. All rights reserved.

Stimulated emission in the blue wavelength region from a copolymer containing PPV segment

The lasing properties of a soluble conjugated polymer, Poly[1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,2-phenylene-1,2-ethenylene-3,5-dimethoxy-1,4-phenylene] (CNMBC-Ph) in chloroform solution were investigated. The third harmonic radiation of a Nd:YAG laser was used as the pump light. The stimulated emission with a linewidth of 15 nm was observed in the blue wavelength region with the peak at 450 nm. The threshold pulse peak power was about 2.8 MW/cm(2). The energy conversion yield of the laser was estimated to be about 3.4%. The maximum peak power of the laser output pulse reached 40 kW. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Photoluminescent properties of organic film in flat optical microcavity

The microcavity is sandwiched between a quarterwavelength distributed Bragg reflector(DBR) and a metal Ag reflective mirror. A single layer of a Tris(8-quinolinolato)aluminum (Alq) film was used as the light-emitting layer. The photoluminescent properties of the optical microcavity and that of the Alq film were studied at the same excitation condition. Compared with the Alq film,the significantly narrowed spectral emission linewidth from 90 nm to 10 nm was observed, the PL emission intensity of the microcavity at the resonant mode is enhanced by the order of 1. The spectral narrowing and intensity enhancement of the microcavity is attributed to the microcavity effect.

Effect of end substitution on optical properties and molecular orientation of distyrylbenzene derivatives in thin film

Three distyrylbenzene (DSB) derivatives were vacuum-evaporated on a (001) surface of KBr. DSB derivative molecules formed nuclei by interaction between the electron donative methoxyl group and Br- ion of the substrate crystal and oriented their longitudinal axis obliquely to the substrate surface. The peak shift between the emission peaks of solution and film decreased depending on the number of substituent. This phenomenon was originated to reduction of molecular interaction between neighboring molecules by steric hindrance of end substituents. (C) 2000 Elsevier Science S.A. All rights reserved.

Photoluminescent properties of dye-doped poly(N-vinyleabzole) (PVK) in microcavity

A surface emitting microcavity was formed by sandwiching a polymer film containing poly(N-vinyleabzole) (PVK). 8-hydroxyquinoline aluminium (Alq(3)) and 4-(Dicyanome thylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-Pyran(DCM) between a distributed Bragg reflector (DBR) with a reflectivity of 99% and a silver film. The sample was optically pumped with 250 ps pulses at 2 Hz repetition rate by a 355 nm line of the third harmonic of a mode-lock Nd:YAG laser. The lasing phenomenon was observed in DCM-doped PVK microcavity. The full width at half maximum (FWHM) was 3 nm with the peak wavelength at 602 nm. The threshold energy for lasing was estimated to be about 3 mu J. (C) 2000 Elsevier Science S.A. All rights reserved.

Optical spectroscopy properties and charge compensation of BaLiF3 doped with Ce3+

The excitation and emission spectra of the BaLiF3:Ce3+ phosphors synthesized through solid state reaction have been measured. By investigating the properties of the excitation spectra we point out that the variation in the excitation spectra with the amount of CeF3 dopant results from the different patterns of charge compensation in the matrices. The vacancies of Li+ ions are the favorable charge compensation pattern at low concentration of CeF3 doped, but interstitial F- ions are the major charge compensation pattern when the concentration of CeF3 doped goes beyond a certain value. (C) 2000 Academic Press

Mild hydrothermal synthesis and optical properties of the complex fluoride KMgF3 doped with Eu

KMgF3 doped with Eu was synthesized by mild hydrothermal method at 240 degreesC for the first time. The excitation and emission spectra of the KMgF3 : Eu2+ phosphor were measured. Comparing with the sample synthesized through solid state reaction, the variation in the excitation spectra at 360 nm resulted from the existences of V-K color centers; the low emission intensity was due to Eu2+ having transferred part energy to V-K color centers.

A comparative study on the electroluminescence properties of some terbium beta-diketonate complexes

By comparing the phosphorescence spectra of Gd(acac)(3) (acac=acetylacetone), Gd(TFacac)3 (TFacac=1,1,1-trifluoroacetylacetone), the effects of fluorine replacement of hydrogen on the triplet state energy of the ligands were revealed. Fluorine can lower the triplet state energy of Hacac and make it more suitable for energy transfer towards the D-5(4) state of terbium. Organic electroluminescent devices (OELDs) with the corresponding trivalent terbium complexes as emissive layers were fabricated. Triple-layer-type devices with a structure of glass substrate/ITO (indium tin oxide)/PVK [poly(N-vinylcarbazole)]/PVK : Tb complex: PBD [2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole]/PBD/Al exhibit bright green luminescence upon applying a dc voltage. The luminance of a device with Tb(TFacac)(3)phen (1,10-phenanthroline) and Tb( TFacac) 3 as emissive layer is higher than that of the corresponding devices with Tb(acac)(3)(phen) and Tb(acac)(3) as emissive layers. The EL device with Tb(TFacac)(3)(phen) as emitter exhibits characteristic emission of Tb3+ ions with a maximum luminance of 58 cd m(-2) at 25 V.

Preparation, characterization and luminescent properties of MCM-41 type materials impregnated with rare earth complex

Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.

Preparation and luminescence properties of lanthanide complexes and their silica-based composites

Binary complexes of europium and terbium with N-propyl-4-carboxyphthalimide (NP) were prepared and characterized. The luminescence behaviors of the lanthanide complexes as well as their doped silica-based composites were investigated by fluorescence spectra. The results indicated that the lanthanide complexes showed fewer emission lines and slightly lower intensities in silica matrix than that of corresponding pure complexes. The lifetimes of the lanthanide complexes became longer when they were incorporated in silica matrix. (C) 2001 Elsevier Science B.V. All rights reserved.