Optics and Spectral Investigation in Dy^(3+)-Doped Borate Glasses

Dy^3＋-doped borate glasses （LBLB） with high effective visible fluorescence emission were synthesized. The absorption spectrum and fluorescence spectrum of this glass were measured and analyzed. By using J-O theory, the oscillator strengths for some absorption transitions were calculated according to the absorption spectra. The intensity parameters Ω1 （t = 2, 4, 6） of Dy^3＋ were determined by using a least-squares fitting approach, and the values are 4.04 × 10^-20, 1.30 × 10^-20 and 1.82 × 10^-20 cm, respectively. The root-mean-square deviation δrma was calculated. Under UV light excitation, Dy^3＋-doped borate glasses （LBLB） emit intense yellowish white lights. The excitation spectrum indicates that argon laser is the effective excitation source in Dy^3＋-doped LBLB glasses

Crystal Structure and Luminescence Spectra of Ternary Europium（Ⅲ） Complex［Eu（DBM）_3（2，2＇－BIPY）］（HDBM）

The crystal structure of europium tri(dibenzoylmethanate) complex with 2.2'-bipyridyl,C70 H57 N2 O8 Eu, has been determined by X-ray diffraction. The complex crystallizes in the triclinic space group P1. The cell dimensions are a=1.3375(1) nm.b=1.8591(2) nm, c=1.1339(3) nm,α= 95.89(9) °,β=93.36(1)°,γ=85.48(1)° and Z=2. The total number of 5413 independent reflections with I>3σ(I) were used for the structure determination. The final calculated R value is 0.039. The central europium ion is octa-coordinated by six oxygen atoms and two nitrogen atoms forming a distorted square antipnsm (SAP) with the local symmetry C1. Using the Eu3+ ion as a luminescence probe. the high resolution excitation and emission spectra measured at 77 K indicate only one Eu3+ site existing in the complex. The emission spectra of 5D0→7Fj transition display the symmetry of the Eu3+ site is C1.

Study on Visible Photoluminescence and Absorption Spectra of Fergusonite Group Minerals

Visible photoluminescence and absorption spectra of the metamict and annealing-recrystallized fergusonite and brocenite, found in Bayun Obo ore deposit in China, were determined and discussed. The results show that the glow centers of the fergusonite group minerals are Er3+ and Eu3 + when 488.0 and 514.5 nm lasers are used as excitation sources. The luminescence of fergusonites results mainly from Er3+, whereas that of brocenites is produced by Er3+ and Eu3+. The absorption spectra indicate that Nd3 + may be an important sensitizer to the luminescence of Er3 + and Eu3+.

SYNTHESIS OF MeO-SiO_2:Eu^(3+),Bi^(3+)LUMINOPUORS BY THE SOL-GEL METHOD AND A STUDY OF THEIR LUMINESCENCE SPECTRA

The luminophors MeO-SiO_2:Eu^(3+),Bi^(3+)and MeO-SiO_2Bi^(3+)(Me=Mg.Sr)were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica.The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi^(3+)ions to the Eu^(3+)ions.

Eu^（3＋） Ion as Luminescent Probe：Eu^（3＋） Sites in Eu（PBI）_3·phen and ［Eu（PBI）_3·C_2H_5OH·H_2O］·H_2O Complexes

The luminescence of Eu￣(3+) in Eu(PBI)_3 phen and [Eu (PBI)_3 ·C_2H_5OH ·H_2O] ·H_2O(PBI: 3-phenyl-4-benzoyl isoxazate ,phen: 1, 10-phenanthroline) is reported. It is shown that theEu￣(3+) ions in Eu(PBI)_3 phen are positioned on the two sites and the various lines are assigned to eachsite. However, Eu￣(3+) ions occupy a single site in [Eu(PBI)_3 ·C_2H_5OH ·H_2O] ·H_2O and the crystal field splittings of the￣7F_(1￣4) levels are much larger than those in Eu (PBI)_3phen.

Influence of ligand architecture on the structure of coordination centre in dimeric europium carboxylates with 1,10-phenanthroline

Methods of optical spectroscopy and X-ray crystallography data were used to examine the effect of architecture of carboxylate anions on structure of the Eu3＋ coordination centre in europium earboxylates with 1,10-phenanthroline Eu（RCOO）3·Phen. Luminescence spectra of europium acetate, nitropropionate, benzoate, naphthylcarboxylates, phenylacetates, phenoxyacetate, triphenylpropionate were investigated. A few of europium carboxylates with 2,2＇-bipyridine Eu（RCOO）3·Bpy and europium salts Eu（RCOO）3·nH2O were also studied. Vibrational IR and Raman spectra of phenylacetate family were analyzed. The crystal structure of nitropropionate Eu（NO2C2H4COO）3·Phen was solved by X-my diffraction method. The predominant influence of steric hindrances on Eu^3＋ coordination centre was observed at increase of the size of aromatic flagment of carboxylate anions. It was demonstrated, that introduction of the methylene bridges between the carboxylic group and aromatic rings of ligand weakens the effect of steric factor.

Synthesis and Luminescence Properties of Gd_2O_3∶Eu^(3+) Phosphors

Gd 2O 3∶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 Gd 2O 3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd 2O 3∶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 of Eu(MBA)_2NO_3Phen Complexes

At 77 K excitation spectra,luminescence and time-resolved spectra of Eu(o-MBA)2NO3 Phen and Eu(m-MBA)2NO3 Phen (MBA:methylbenzoate,Phen 1,10-phenanthroline) complexes were measured. Spectral data show that because of steric effect of ortho-methyl substituent there occur two Eu3+ sites with slightly different chemical environment in the Eu(o-MBA)2NO3Phen complex.The local symmetnes for the central metal ions are C2v and C1,C2 or Cs,respectively.However,there is only one Eu3+ site in the Eut(m-MBA)2NO3Phen complex which is similar to the C2v Eu3+ site of the previous complex.This demonstrates that the Eu3+ ion can be used as a conformational probe in the solid state compounds.

Structural, Morphological and Optical Properties of ZnO Thin Films Grown on γ-LiA1O_2 Substrate by Pulsed Laser Deposition

ZnO thin films were deposited on the substrates of （100） γ-LiAlO2 at 400,550 and 700℃ using pulsed laser deposition （PLD） with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is 400℃, the grain size of the film is less than 1μm observed by Leitz microscope and measured by X-ray diffraction （XRD）. As the substrate temperature increases to 550℃, highly-preferred c-orientation and high-quality ZnO film can be attained.While the substrate temperature rises to 700℃, more defects appears on the surface of film and the ZnO films become polycrystalline again possibly because more Li of the substrate diffused into the ZnO film at high substrate temperature. The photoluminescence （PL） spectra of ZnO films at room temperature show the blue emission peaks centered at 430 nm. We suggest that the blue emission corresponds to the electron transition from the level of interstitial Zn to the valence band. Meanwhile, the films grown on γ-LiAl02 （LAO） exhibit green emission centered at 540 nm, which seemed to be ascribed to excess zinc and/or oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition.

Sm^(3+) ions doped Sm_(2)Si_(2)O_(7)-based glass ceramics:Crystallization,luminescence and energy transfer process through heat treatment

Sm^(3+) ions incorporated Sm_(2)Si_(2)O_(7) crystalline phase formed in the aluminoborosilicate glass matrix synthesized via melting quenching technique followed by heat-treatment process is reported herewith.The preliminary confirmation on the obtained glass ceramics was made through X-ray diffration(XRD) studies.Formation of non-bridging oxygens(NBOs) in the glass network and the modes of vibrations of network units we re analyzed through Fourier transform infrared spectroscopy(FTIR) studies.Surface morphology of heat-treated samples at varying temperatures was determined via a field emission scanning electron microscope(FESEM).The absorption studies on heat-treated samples signify the low bandgap values and high Urbach energy values due to improved crystallinity in the glass network.Judd-Ofelt intensity parameters identified for visible absorption transitions follow the trend of Ω_(4)>Ω_(2)>Ω_(6).Excitation and emission studies on heat-treated samples show improvement in their intensities compared to the unheated base glass.The thermal quenching is observed at higher temperatures(540 and 580℃ for 3 h) of heat-treated samples.Calculations based on luminescence spectra including radiative transition probability,stimulated emission cross-section and branching ratio show good results for glass ceramics prior to precursor glass.Longer lifetimes of Sm^(3+) ions(milliseconds) in the level ^(4)G_(5/2) are seen for glass ceramics.Color coordinates suggest the reddish-orange emissions from prepared glass ceramics.Thus,Sm^(3+) doped Sm_(2)Si_(2)O_(7) glass ceramics are favorable materials for solid-state lighting and laser applications.

Synthesis of Eu(III) and Tb(III) Complexes with Two New Amide Type Podands and Their Luminescence Properties

Two new amide type podands L 1 and L 2(L 1=1,1,1 tris{[(2 benzylaminoformyl)phenoxyl]methyl}propane, L 2=1,3,5 trimethyl 2,4,6 tris{[(2 benzylaminoformyl)phenoxyl]methyl}benzene) and their europium and terbium nitrates complexes were synthesized. The luminescence properties of these complexes were also studied.