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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

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

Determination of Poly(Diallyldimethylammonium Chloride)via Spectrophotometric Titration with Coomassie Brilliant Blue G Dye

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光谱学与光谱分析 2016年第2期36卷 583-587页

作者： Alexander shyichuk Dorota Ziókowska Jan Lamkiewicz UTP University of Science and Technology Faculty of Chemical Technology and Engineering

Poly(diallyldimethylammonium chloride)(PDDA)is used as organic coagulant in water purification and auxiliary agent in paper *** of PDDA in aqueous solutions is carried out usually by means of polyelectrolyte titration using streaming current detector or o-Toluidine Blue dye for endpoint *** proposed method of PDDA assay takes advantage of Coomassie Brilliant Blue G dye having strong affinity to cationic *** of PDDA solution with the dye is carried out measuring absorbance at *** points of the obtained zigzag photometric curves have good repeatability provided that titration rate is low enough to attain endpoint for 1hour or *** method assures rectilinear calibration(R2=0.999 5)in the broad range of PDDA concentrations from 0.3to 9.6mg·dm^(-3).

关键词： PDADMAC PolyDADMAC Cationic polyelectrolyte Colloid titration