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Photoluminescence properties of nanosized strontium-yttrium borate phosphor Sr_3Y_2(BO_3) _4:Eu^(3+) obtained by the sol-gel Pechini method

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Journal of Rare Earths 2011年第12期29卷 1161-1165页

作者： A.A.Shyichuk S.lis Department of Rare Earth Faculty of ChemistryAdam Mickiewicz Uniwersity

Mixed strontium-yttrium borate phosphor Sr3Y2（BO3）4 doped with Eu^3＋ ions was obtained by the sol-gel Pechini method. Crystal structure of the synthesized compound was analyzed by X-ray powder diffraction. Optimal conditions for the synthesis were found. Photophysical properties of the phosphor samples were investigated by collecting excitation and luminescence spectra as well as measuring lumi- nescence lifetime. Judd-Ofelt analysis showed that Eu^3＋ ions occupied Y^3＋ sites in the crystalline network. The studied compound showed a red emission with the quantum yield of 54%-55% and can be potentially used as phosphor for plasma display panels and luminescent tubes.

关键词： strontium-yttrium borate luminophor Eu^3+ sol-gel method rare earths

Synthesis of luminescent KY_3F_(10) nanopowder multi-doped with lanthanide ions by a co-precipitation method

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Journal of Rare Earths 2016年第8期34卷 808-813页

作者： Szymon Goderski Marcin Runowski Stefan lis Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University

A series of KY3F10 nanophosphors doped with Gd3＋, Ce3＋ and Eu3＋ ions were obtained with the use of a co-precipitation method. The resulting products were white precipitates, consisting of spherical particles with diameter about 150-200 nm, which was confirmed using transmission electron microscopy （TEM） technique. Powder X-ray diffraction （XRD） and energy dispersive X-ray analysis （EDX） measurements confirmed appropriate structures of the nanoparticles obtained. Spectroscopic properties of the prod- ucts were examined on the basis of the measured excitation/emission spectra and luminescence decay curves. The synthesized sam- ples showed orange-red luminescence, characteristic for Eu3＋ ions. The reaction process was performed in required alkaline pH ad- justed with the use of ethylenediaminetetraacetic acid （EDTA） and potassium hydroxide. The samples containing large amounts of Gd3＋ dooant ions exhibited a tendencv to form nroducts with different momhologies.

关键词： : fluorides co-precipitation nanophosphors luminescence nanopowders Ce3+/Gd3+/Eu3+ doping rare earths

Photoluminescent properties of LaF_3:Eu^(3+) and GdF_3:Eu^(3+)nanoparticles prepared by co-precipitation method

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Journal of Rare Earths 2009年第4期27卷 588-592页

作者： T.Grzyb S.lis Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University

GdF3：Eu^3＋ and GdF3：Eu^3＋ nanoparticles were prepared by a co-precipitation method in the presence of the chelating agent, citric acid. The structural properties of the products were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The average crystallite size was estimated from the full-width at half-maximum （FWHM） of the diffraction peaks by the Scherrer equation. The sizes of the nanoparticles were 12 nm for LaF3：Eu3＋ and 17 nm for GdF3：Eu^3＋. The luminescent properties of the nanoparticles were investigated by excitation and emission spectra. Energy transfer from Gd3＋ to Eu3＋ was observed.

关键词： nanofluorides phosphors luminescence energy transfer rare earths

Photoluminescence and electrochemiluminescence studies of chosen rare earths systems

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Journal of Rare Earths 2008年第2期26卷 192-197页

作者： Stefan lis Slawomir But Krzysztof Staninski Monika Jesiolowska Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University Grunwaldzka 6

Eu（Ⅲ） complexes with chosen Keggin polyoxomatalates, POM, containing organic counter cations （tetrabutylarnmonium, tetrabutylphosphonium, triphenylethylphosphonium）, were synthesized, and their photophysical properties were studied. The synthesized complexes had the general formula of XnH5-n[EuSiW11O39], formulated based on the results of elemental and thermogravimetric analysis and FTIR spectroscopy. The photophysical properties of the obtained compounds were investigated using photoluminescence and electrochemiluminescence, ECL, methods in solutions and solids. The most intense luminescence of Eu（Ⅲ） was observed for the complexes with tetrabutylarnmonium cations. After the addition of phenanthroline to the XnH5-n[EuSiW11O39] solutions, a large increase in the Eu（Ⅲ） luminescence intensity and a lengthening of its luminescence lifetime were observed as a result of the formation of ternary complexes. Attempts to apply ECL as a method of light emission by generating species capable of forming excited states in Ln/POMs, i.e., Tb（Ⅲ） and Eu（Ⅲ） in the Na9EuW10O36 and Na9TbW10O36 complexes, were made. The influence of the POM complexes on the ECL was also tested using the Tb/EDDHA （EDDA=ethylenediamine di（o-hydroxyphenylacetic acid）） complex, which is effective in generating ECL.

关键词： Ln(Ⅲ) luminescence electrochemiluminescence polyoxometalates complexes rare earths

Structure modeling of terbium doped strontium-lanthanum borate

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Journal of Rare Earths 2014年第3期32卷 248-253页

作者： A.Shyichuk S.lis G.Meinrath Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University Radioactivity Environment Remediation (RER) Consultants

Terbium doped strontium-lanthanum borate, Sr3La2（BO3）4：Tb （SLB）, was studied by semi-empirical computational ap- proaches using PM6 parametrization and the SPARKLE model for lanthanide（Ⅲ）（Ln（Ⅲ）） cations. The focus of interest was on structural aspects, e.g. the cell parameters and distribution of dopant ions between various sites as a function of dopant concentration. The cell linear dimensions were calculated to decrease linearly with increasing dopant molar concentration. SLB offered two sites for the dopant. Calculations predicted that one of these sites should be preferred by the Tb（Ⅲ） dopant. The optimized cell dimensions as well as the total energies differed for structures with dopant exclusively in site 1 or site 2. Computational predictions were tested against experimental results obtained for SLB synthesized by sol-gel method varying the dopant concentration. The agreement be- tween experimental and computational results was found sufficiently promising to continue the computational studies.

关键词： strontium-lanthanum borate terbium structure calculations rare earths

Synthesis, structural and spectroscopic studies on GdBO_3:Yb^(3+)/Tb^(3+)@SiO_2 core-shell nanostructures

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Journal of Rare Earths 2015年第11期33卷 1148-1154页

作者： Konrad Kubasiewicz Marcin Runowski Stefan lis Agata Szczeszak Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University

The presented study concerned up-converting core/shell type nanomaterials based on lanthanide（Ⅲ） ions, Ln（Ⅲ）, doped orthoborates. The system studied composed of the GdBO3 doped with Yb^3＋/Tb^3＋ luminescent core ensured an effective cooperative sensitization up-conversion, resulting in a bright green luminescence. The silica coating process was performed by a modified St？ber method, which resulted in the formation of core-shell nanostructures, making them suitable for bioapplications. The nanophosphors and nanocomposites were obtained by various methods, such as co-precipitation in the presence of Triton X-100 and micelle synthesis with ethylenediaminetetraacetic acid（EDTA） as organic modifiers/surfactants. The synthesized nanomaterials were characterized with the use of powder X-ray diffraction（XRD）, infrared light absorption with Fourier transform FT-IR spectra, transmission electron microscopy（TEM）, up-conversion emission spectra under IR light, as well as excitation spectra, emission spectra and fluorescence lifetimes under UV light, and their photophysical properties were compared.

关键词： Ln(Ⅲ) ions GdB O3 silica coating core-shell nanocomposites up-conversion cooperative sensitization rare earths

Spectroscopic properties of Eu^(3+) doped YBO_3 nanophosphors synthesized by modified co-precipitation method

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Journal of Rare Earths 2011年第12期29卷 1142-1146页

作者： A.Szczeszak S.lis V.Nagirnyi Department of Rare Earths Faculty of ChemistryAdam Mickiewicz University Institute of Physics University of Tartu

Y1-xEuxBO3 nanophosphors were synthesized by a modified co-precipitation method. The structure of the obtained nanocrystals was determined by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The average crystallite size was calculated from the full-width at half-maximum （FWHM） of the diffraction peaks by the Scherrer equation. The average particles size was 25±10 nm. The spectroscopic properties of the Y1-xEuxBO3 nanoborates were characterized by excitation and emission spectra under UV and VUV excitation. In order to improve colour purity, the chromaticity coordinates were also calculated.

关键词： YBO3:Eu^3+ co-precipitation nanophosphor luminescence VUV rare earths

Pairs of Ln(Ⅲ)dopant ions in crystalline solid luminophores:an ab initio computational study

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Journal of Rare Earths 2016年第8期34卷 820-827页

作者： A.Shyichuk G.Meinrath S.lis Department of Rare Earths Faculty of ChemistryAdam Mickiewicz UniversityUmultowska 89b61-614 PoznafiPoland Radioactivity Environment Remediation(RER)Consultants Fuchsbauerweg 5094036 PassauGermany

Formation of dopant ions clusters in solid （glass） luminophores may affect efficiency of non-radiative energy transfer proc- esses between dopant （photoactivator） ions via shortening of the effective distance between them. This study was based on the as- sumption that the distance between the dopant ions affects the energy of crystal volume at proximity. According to this idea, semi-empirical and ab initio density functional theory （DFT） calculations were performed on various supercells of YVO4：Eu3＋ as a model system. It was noted that a shorter Eu-Eu distance resulted in lower total energy of the system, compared to an analogous structure with distant Eu3＋ ions. As lower energy configurations are preferred, the observed phenomenon was considered to be related to dopant ions clusters formation. Additionally, the values of energies obtained from DFT calculations were used to estimate the per- centage of dopant ions occurring as pairs, for different dopant concentrations. The estimation agreed quite well with the available lit- erature data.

关键词： crystalline luminophore lanthanides vanadate DFT dopant clustering rare earths

Nanosized complex fluorides based on Eu^(3+) doped Sr_2LnF_7(Ln=La, Gd)

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Journal of Rare Earths 2014年第3期32卷 242-247页

作者： M.Runowski S.Balabhadra S.lis Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University

A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.

关键词： luminescence Eu3+ doping complex strontium lanthanide fluorides nanoparticles Sr2LnF7 Sr0.69La0.31F2.31 rare earths