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crystal structure and luminescence dynamics of highly pure liM(PO_(3))_(3):Eu^(3+)(M=Sr,ca) red phosphors for white light emitting diodes

饮用水安全控制会议暨中国土木工程学会水工业分会给水专业...

作者：马聪于水利 Heijman,S.G.J. rietveld,l.c. Shi Wenxin 天津工业大学同济大学污染控制与资源化研究国家重点实验室代尔夫特理工大学卫生工程系

本文主要对DEMIFlUSH工艺减轻地表水处理过程中膜污染的可行性进行了研究,并优化了中式运行条件。其减轻膜污染的主要原理为:低离子浓度、低电导率的RO出水反洗减弱了钙离子对NOM分子和超滤膜的电荷屏蔽作用与钙离子架桥作用,因此恢复了... 详细信息

本文主要对DEMIFlUSH工艺减轻地表水处理过程中膜污染的可行性进行了研究,并优化了中式运行条件。其减轻膜污染的主要原理为:低离子浓度、低电导率的RO出水反洗减弱了钙离子对NOM分子和超滤膜的电荷屏蔽作用与钙离子架桥作用,因此恢复了NOM分子与UF膜表面之间的排斥力,粘附在膜表面的NOM分子也更容易随反洗水被冲刷掉,从而膜污染得到减轻。实验结果表明:RO出水作为反洗水可以有效控制膜污染;过滤30分钟,通量为55 l/(m·h);反洗30秒,通量为250 l/(m·h)为最经济可行工况;不管采用新旧膜,处理低温(低于11度)地表水,每天1次EcB清洗(浸泡20分钟)可以有效减轻不可逆膜污染,保证DEMIFlUSH工艺长久稳定运行。

关键词：反洗 RO出水膜污染超滤地表水中式

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Journal of Rare Earths 2024年第8期42卷 1470-1478,I0002页

作者： Payal Khajuria M.Manhas A.K.Bedyal Ankush Vij H.c.Swart Vinay Kumar Department of Physics and Astronomical Sciences Central University of JammuRahy-Suchani.Samba1143J&KIndia Department of Physics School of SciencesCluster University of JammuCanal RoadJammu180001India Department of Physics University of Petroleum and Energy StudiesDehradunUttarakhand248007India Department of Physics University of the Free StateP.O.Box 339BloemfonteinZA 9300South Africa

Highly pure red phosphors liM(PO_(3))_(3):Eu^(3+)(M=Sr,ca) doped with Eu^(3+)(1 mol%) were synthesized via solution combustion method and their crystal structure and luminescence dynamics were studied to explore its suitability in white light emitting *** rietveld refinement analysis of the powder Xray diffraction patterns reveals that the phosphors belong to the pure triclinic phase of liSr(PO_(3))_(3) and l.c.(PO_(3)) with space group P-1(2).The scanning el.c.ron microscopy images showed the agglomerated *** photoluminescence emission spectra under 393 nm show an orange band at 594 nm and a red band at 613 nm ascribed to ^(5)D_(0)→^(7)F_(1).^(5)D_(0)→^(7)F_(2) transitions of Eu^(3+)ion in both the ***,the spectroscopic properties such as luminescence behaviour,and Stark splitting were used to examine the symmetry of Eu^(3+)ions in liM(PO_(3))_(3):Es^(3+)(M=Sr,ca) phosphors in terms of distortion induced upon *** Stark splitting shows that the actual site symmetry for Eu^(3+)ion was estimated to be D_(2) type for both *** photometric properties of l.c.(PO_(3))_(3):Eu^(3+)such as commission International de l'Eclairage coordinates(x=0.64,y=0.36) near to the standard one(red),high color purity(95%) and higher brightness reveal that the phosphor has the capability of acting as a red component in n-UV white light emitting diodes.

关键词： Photoluminescence Phosphate WlEDs Stark splitting Rare earths

rietveld refinement and optical properties of SrWO_4:Eu^(3+) powders prepared by the non-hydrolytic sol-gel method

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Journal of Rare Earths 2015年第2期33卷 113-128页

作者： P.F.S.Pereira I.c.Nogueira E.longo E.J.Nassar I.l.V.Rosa l.S.cavalcante chemistry Institute University of the State of Sao Paulo Julio de Mesquita Filho-UNESP Francisco DegniAraraquara-SP 14800-900 Brazil lIEc-chemistry Department Federal University of Sao Carlos Via Washington Luis Km 235Sao Carlos-SP 13565-905 Brazil University of Franca-UNIFRAN Via Dr.Armando Sales de OliveiraNo.201 Franca-SP 14404-600 Brazil ccN-DQ-GERATEc University of the State of Piauí Joao Cabral 2231 P.O.Box 391Terezina PI 64002-150 Brazil

We investigated the effect of annealing time on the structure and optical properties of Sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 *** and differential thermal analyses revealed that Sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and rietveld refinement data confirmed that all powders had a scheelite-type tetragonal ***-Raman and Fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]*** properties were investigated by ultraviolet-visible（UV-vis）diffuse refl.c.ance,and photoluminescence（Pl）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of Sr WO4：Eu^3＋ *** properties validated that the Eu^3＋ el.c.ric-dipole（^5D0→^7F2）transition in Pl emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7F2）/（^5D0→^7F1）]band ratios showed that Eu^3＋ ions were l.c.ted in a low symmetry *** Pl emission,ηandτproved the dependence on the annealing time in the behavior of Sr WO4：Eu3＋powders with a higher relative emission Pl intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h.

关键词： SrWO4 rietveld refinement optical band gap Eu^(3+) +-rare earth luminescence

Phase Homogeneity and crystal Structure of Sb_(88)Te_(12) Synthesized by Melt-quench Method

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Acta Metallurgica Sinica(English letters) 2013年第4期26卷 441-446页

作者： c.Rangasami Department of Physics Erode Sengunthar Engineering College

Phase homogeneity and crystal structure of SbsaTe12 alloy synthesized by melt-quench method have been analyzed using X-ray diffraction （XRD） and Raman spectroscopy. rietveld refinement of crystal structure of Sb8sTe12 has revealed the formation of SbsTe3 and Sb phases respectively with 11R and A7 structures （space group is R3m）. Phase fractions of the phases SbsTe3 and Sb have been determined to be 44.44% and 55.56% respectively. Raman spectrum of SbssTe12 has showed a highest intensity peak at 156 cm-1 and another peak at 151.1 cm-1, which correspond to Alg modes of SbsTe3 and element Sb, respectively. Analysis of Raman spectrum has substantiated the results obtained from structure refinement regarding the presence of two different phases.

关键词： SbssTe12 alloy Melt-quench method XRD rietveld refinement Raman spectroscopy Multiphase formation

Experimental.c.arge density distribution and its correlation to structural and optical properties of Sm^3＋ doped Nd2O3 nanophosphors

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Journal of Rare Earths 2017年第11期35卷 1102-1114页

作者： Morris Marieli Antoinette S. Israel G. Sathya Arlin Jose Amali John l. Berchmans K. Sujatha c. Anzline R. Niranjana Devi Post Graduate and Research Department of Physics Tile American College Madurai 625 002 Tamilnadu India El.c.ro-Pyrometallurgy Division CS1R-Central Electrochemical Research Institute Karaikudi 630003 Tamilnadu India School of chemistry Madurai Kamaraj University Madurai 625021 Tamilnadu India

Pure and Smdoped NdOnanophosphors were synthesized using modified Pechini method. The phase formation with symmetry of the sample is confirmed by the rietveld refinement of the powder Xray diffraction(PXRD) data. The surface morphology and the crystallite size were examined using scanning el.c.ron microscopy(SEM) and transmission el.c.ron microscopy(TEM) and the results confirmed that the synthesized particles are in nanosize. The energy-dispersive X-ray(EDX) analysis was done to confirm the purity of the sample. The optical properties of the sample were studied using ultraviolet-visible range(UV-Vis) spectroscopic analysis and photoluminescence studies. The calculated band gap of the synthesized NdOwas found to be higher than that of bulk NdO. The photoluminescence(Pl) of the prepared samples reveals that doping with Sm3+ ion has influenced the optical properties. Quantitative investigation on charge density distribution was done by analysing the 3-dimensional and 2-dimensional.c.arge density maps drawn along the bonding directions. The maximum entropy method(MEM)/rietveld analysis was used for the first time to analyse the charge density in the chosen system. charge density arrangement in the unit cell is correlated to the analysed photoluminescent(Pl) properties. The spectral behaviour of the samples has been explained through charge ordering which are verified using experimental data obtained. The studies on these materials have shown that these nanophosphors will provide promising appl.c.tion for near-ultraviolet lightemitting diodes(n-UV-lEDs).

关键词： Modified Pechini method Photoluminescence MEM/rietveld charge density

Preparation and characterization of ce_(1-x)Dy_(x-y)Sr_yO_(2-δ) system

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Transactions of Nonferrous Metals Society of china 2014年第2期24卷 393-400页

作者： S.RAMESH K.c.JAMES RAJU c.VISHNUVARDHAN REDDY School of Physics University of Hyderabad Department of Physics Osmania University

The effect of dysprosium and strontium on the total ionic conductivity of ceria in the system ce1-xDyx-ySryO2-δ was studied. In this system, few compositions were prepared with x=0.15, y=0.015, 0.03 and 0.045 by modified sol-gel process using maltose and pectin as organic precursors. rietveld refinement of XRD patterns confirms the cubic structure with space group Fm3m . SEM images show relatively uniform grains with clean and distinct grain boundaries. Four probe Ac impedance measurements were carried out to evaluate the total ionic conductivity in the temperature range of 150-500 ℃ and frequency range of 40 Hz-1 MHz. The composition ce0.85Dy0.12Sr0.03O2-δshows higher el.c.rical.c.nductivity than single-doped ceria samples.

关键词： el.c.rolyte Sr-Dy doping impedance spectroscopy conductivity

Properties of Al_2O_3-Sm_2O_3-ceO_2 el.c.rolyte

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Transactions of Nonferrous Metals Society of china 2012年第6期22卷 1486-1494页

作者： S.RAMESH K.c.J.RAJU c.V.REDDY School of Physics University of HyderabadHyderabad 500046India Department of Physics Osmania UniversityHyderabad 500007India

cel-xSmxO2 （x=0, 0.1, 0.2 and 0.3） and Sm-doped ceria＋（2%-8%）Al2O3 were synthesized through sol-gel process followed by low temperature combustion. The synthesis, structure, densification, conductivity and thermal expansion were studied, and the structure and phase were confirmed by XRD. Dense ceramics were obtained through sintering the pellets at 1300 ℃. 2% and 4% Al2O3 were added into ce0.8Sm0.2O2 to promote the densification at 1250 ℃. The surface morphology of the sintered pellets was analyzed using SEM. A two-probe Ac impedance spectroscopy was used to study the total ionic conductivity.

关键词： sol-gel process XRD-rietveld impedance spectroscopy ionic conductivity el.c.rolyte ceramics

预测感染性结膜炎的致病菌:联合症状与体征的队列研究

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世界核心医学期刊文摘（眼科学分册） 2005年第1期1卷 2-3页

作者：肖颖 rietveld R.P Ter Riet G Bindels P.J.E Department of General Pra c -tice Academic Medical CenterUniv ersity of Ams -terdamMeiberg dreef 151105AZAm sterdamNetherlands

Objective:To find an efficient set o f diagnostic indicators that are optimally informative in th e diagnosis of a bacterial origin of acute infectious ***:cohort study involving consecutive patien *** of index tests and reference standard were coll.c.ed independently from each ***:25Dutch health ***:184adults presenting with a red eye a nd either(muco)purulent discharge or glued eyelid(s),not wearing contact *** outcome measures:Prob ability of a positive bacterial.c.lture,given different combinations of index test results;area under receiver operating characteristics ***:logistic regression analysis showed optimal diagnostic discrimination for the c ombination of early morn-ing glued eye(s),itch,and a history of *** first of these indicators increased the likelihood of a bac-terial.c.use,whereas the other two d ecreased it The area under the receiver operating characteristics curve for this combination of symptoms was 0.74(95%confidence in-terval 0.63to 0.80).The overall prevalence of bacteria l involvement of 32%could be lowered t o 4%or raised to77%,depending on the pattern of index test ***:A bacterial origin of co mplaints indicative of acute infectious conjunctivitis can be made much more likely or unlikely by the answers to t hree simple questions posed during clinical history takin g(possibly by tele-phone).These results may have consequences for more targeted prescription of ocular ant ibiotics.

关键词：感染性结膜炎队列研究培养阳性率细菌感染睑粘连角膜接触镜最佳信息测试指标佩戴者脓性分泌物

Effect of Sn on synthesis of nanocrystalline Ti-based alloy with fcc structure

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Transactions of Nonferrous Metals Society of china 2020年第8期30卷 2119-2131页

作者： c.AGUIlAR E.PIO A.MEDINA c.PARRA R.MANGAlARAJA P.MARTIN I.AlFONSO K.TEllO Departamento de Ingeniería Metalúrgica y de Materiales Departamento de Física(+)Universidad Técnica Federico Santa MaríaValparaísoChile Instituto de Investigación en Metalurgia y Materiales Universidad Michoacana de San Nicolás de HidalgoMoreliaMéxico laboratorio de cerámicos Avanzados y Nanotecnologia Departamento de Ingeniería de MaterialesUniversidad de ConcepciónConcepciónChile Instituto de Investigaciones en Materiales Universidad Nacional Autónoma de MéxicoCampus Morelia UNAMMoreliaMéxico

The effect of the amount of Sn on the formation of fcc phase in Ti-13 Ta-x Sn(x=3,6,9 and 12,at.%)alloys was *** alloys were synthesized by mechanical alloying using a planetary mill,jar and balls of stabilized *** rietveld refinement,it was found that the obtained fcc phase has crystallite size smaller than 10 nm and microstrain larger than *** conditions are required to form an fcc phase in Ti-based *** all samples,the microstructure of the fcc phase consists of equiaxial.c.ystallites with sizes smaller than 10 *** largest presence of fcc phase in the studied Ti alloy was found with 6 at.%Sn,because this alloy exhibits the largest microstrain(1.5×10-2)and crystallite size of 6.5 *** data reveal that a solid solution and an amorphous phase were formed during *** necessary conditions to promote the formation of solid solution and amorphous phases were determined using thermodynamic *** the amount of Sn increases,the energy required to form an amorphous phase varies from approximately 10 to approximately-5 k J/mol for 3 and 12 at.%Sn,*** thermodynamic calculations are in agreement with XRD patterns analysis and HRTEM results.

关键词： Ti-based alloy phase transformation fcc phase rietveld analysis mechanical alloying