Preparation and Luminescence Properties of the New Long Phosphorescent Phosphors Ba_(1-x)Ca_xAl_2O_4∶Eu ~(2 ), Dy~(3 )

Inrecentyears ,SrAl2 O4 ∶Eu2 ,Dy3 ,CaAl2 O4 ∶Eu2 ,Nd3 [1～ 8] andBaAl2 O4 ∶Eu2 ,Dy3 [9]havebeenconsideredasusefulblueandgreenphos phorsbytheirlongdurationphosphorescence .Howev er ,toourknowledge ,thephosphorBa1-xCaxAl2 O4 ∶Eu2 ,Dy3 hasnotbeeninvestigated .TheluminescenceofEu2 isverystronglydepen dentonthehostlattice ,whichcanoccurfromtheul traviolettotheredregionoftheelectromagneticspec trum .Itiswellknownthatthepersistentluminescenceisduetothetrappingofenergyinthed…     

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

Gd2 O3∶Eu3+ isanefficientredemittinglumines centmaterial ,whichcanbeappliedindisplays[1,2 ] .TheconventionalcommercialGd2 O3∶Eu3+ ismainlysynthesizedbyhightemperaturesolid statereactionandchemicalco precipitationmethods .Anadvancedperformanceofdisplaysrequireshighqualityphospho rssuchashighbrightnessandefficiency ,monodisper sityandfinegrainsize .Muchresearchhasanticipatedthatsubmicrometer sizedandnanometerluminescentmaterialswillhavethesepotentialadvantages[3～ 8] ,sosubmicrometer sizedan…     

SrAl_2O_4∶Eu~(2+),Nd~(3+) and Dy~(3+) Long Afterglow Phosphor

Longafterglowphosphorabsorbingenergyfromsolar,lampandotherlightsourcesforashorttimestorestheenergyandexhibitsbrightandlong lastingphosphorescencewhichsuitsthevisualperceptionofthehumaneyewithminimumbrightness 0 32mcd·m- 2 andlastingtimemorethan 8h) .TheSrAl2 O4 ∶Eu2 +,Dy3+phosphorhasbeenknowntobeagreenlongafterglowphosphorwithanemissionpeakat 5 2 0nm[1～ 7] .ThepropertiesofthephosphorwerefurtherexaminedbythegroupofTangMingdaoandMatsuzawaTindetailin 1995and 1996respectively[1,2 ] .Inorde…     

Luminescence Properties of (Y, Gd)Al_3(BO_3)_4∶Eu ~(3 ) under VUV excitation

Thephosphorsasanimportantpartofplasmadis playpanel (PDP)deviceemitvisiblelightundervac uumultraviolet (VUV)excitationof 14 7nmand/or172nmfromXe/Hegasplasma[1] .Untilrecently ,Y2 O3∶Eu3 and (Y ,Gd)BO3∶Eu3 havebeenusedascommercialred emittingphosphorsforPDP[2 - 3] .Butthesematerialsstillhaveshortcomingstobeim proved :lowlightoutputofY2 O3∶Eu3 uponVUVex citationandbadcolorpurityof (Y ,Gd )BO3∶Eu3 [4～ 5] .AluminoborateshavestrongabsorptionintheVUVregion ,andexhibitexcellentma…     

Study on Spectra of La_2CaB_(10)O_(19)∶Eu~(3 ) in VUV-VIS Range

Manyboratesareexcellenthostsforrareearthlu minescence ,forexample ,nowbestredphosphorinplasmadisplaypanel (PDP )is (Y1-xGdx)BO3∶Eu[1] .Boratephosphorsdopedwithrareearthionshavebeenrichlystudiedinthepastfewdecades[2 ,3] .RecentlyWuYichengetal .[4 ] synthesizedanewbo rateLa2 CaB10 O19,whichispotentialnonlinearopticalmaterials.InthisworkweselectedLa2 CaB10 O19ashostofluminescencematerialsbecauseitprobablyisabetterhostforrareearthluminescence .Duetotherequirementofplasmadisplaypenal(PDP)…     

碳酸盐前驱体和CS_2硫化制备SrY_2S_4∶Eu~(2+)红色荧光粉及其表征

以Sr2+,Y3+和Eu3+的混合硝酸盐溶液为阳离子溶液,以(NH4)2CO3为沉淀剂,共沉淀法制备了碳酸盐前驱体,TG-DSC分析结果表明,随着(NH4)2CO3浓度的升高,前驱体组成由碱式碳酸盐向正盐转变。以CS2为硫化剂,高温煅烧前驱体合成了SrY2S4∶Eu2+红色荧光粉。XRD表明前驱体经800℃处理得到纯相SrY2S4。荧光光谱和SEM研究表明在[Sr(NO3)2+Eu(NO3)3]∶[Y(NO3)3]∶[(NH4)2CO3]=0.25∶0.50∶2.00(摩尔比)条件下制备前驱体,然后1050℃煅烧4 h所得荧光粉的发光强度最大,粒径小于1μm,粒子形貌呈椭球。Eu2+在SrY2S4基质中的最佳掺杂摩尔分数是0.6%。     

Effect of TSL and PSL in Al~(3+)-Doped BaFBr∶Eu~(2+) at Difference Synthesis Conditions

BaFBr∶Eu2 +,asphoto gatedholeburningmateri al[1] ,scintillatorcrystallinematerialandX rayimagestoragematerial ,iscalledphotostimulatedluminescence(PSL)material[2 ] .Theimagingplate (IP)madeofthesephosphorsisnowusedwidelyasdisplayoftwo dimen sionalimagescausedbyionizationradiation[3] .Thecommercialapplicationofthesematerialsbe ganin 1983.Becauseofapplicationofthesephospho rs ,theconventionalX rayfilmmaybereplacedbythescreenmadeofPSLphosphors (alsocalledimagingplate ,IP) [4 ] .IPhasnotab…     

静电纺丝技术制备Y2O3∶Eu3+ 纳米纤维

采用静电纺丝技术制备了PVP/[Y(NO3)3+Eu(NO3)3]复合纳米纤维,研究了反应体系的最佳组成,系统地讨论了静电纺丝工艺的影响,获得了最佳制备条件.将PVP/[Y(NO3)3+Eu(NO3)3]复合纳米纤维在900℃焙烧10h,获得了晶态的Y2O3∶Eu3+ 纳米纤维.XRD分析表明,PVP/[Y(NO3)3+Eu(NO3)3]复合纤维为无定型,Y2O3∶Eu3+ 发光纳米纤维属于体心立方晶系,空间群为Ia3.SEM分析表明,PVP/[Y(NO3)3+Eu(NO3)3]复合纳米纤维表面光滑,平均直径约为150nm;Y2O3∶Eu3+ 发光纳米纤维的直径约为50nm.     

Preparation, Structural Analysis and Luminescence Properties of Nanocrystalline Phosphor Gd_2O_3∶Eu

Gd2 O3isagoodhostmaterialforluminescenceandhasbeenstudiedwelltheseyears .Gd2 O3dopedwithrareearth (RE)ionsisanidealsystemforfunda mentalresearchsuchasenergytransfer[1] .Moreover ,Gd2 O3∶REhasextensiveuse .Especially ,asahighefficientred emissionluminescentmaterial ,cubicGd2 O3∶EuhasbeenwidelyusedinX rayscintillatormaterial ,highdefinitionprojectiontelevisions ,flatpaneldisplaysandphotoelectronicapparatus[2 ,3] .Inthepastcoupleofdecades ,therehasbeenadramaticgrowthofinterestinnanocrystal…     

Characterization of Y_2O_2S∶Eu ~(3+), Mg~(2+), Ti~(4+) Long-Lasting Phosphor Synthesized by Flux Method

Long lastingphosphorescence(LLP)isaproper tyofphosphorswithlongdecaytime,rangingfroma fewminutestotensofhours[1].Inrecentyears,LLP materialshavebeenwidelyusedinmanyfieldssuch asroadsigns,emergencylighting,graphicarts,inte riordecoration,automobileinstrument,andoptical datastorage[2～4].Buttodate,theprogressonred phosphorescenceisveryslow.TheredLLPmaterialbasedonsulfide(CaS∶Eu3+)hasnearly3hafterglow.However,itisex tremelysensitivetomoistureandthuschemicallyun stable[5].CaTiO3∶Pr3+,BaT…     

Characterization of Y2O2S:Eu3+, Mg2+, Ti4+ Long-Lasting Phosphor Synthesized by Flux Method

Long-lasting phosphor Y2O2S∶Eu3 , Mg2 , Ti4 was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu2O3 content in Y2O2S∶Eu3 x(0.01≤x≤0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y2O2S∶ Eu3 crystal structure, Eu3 ions only replaced Y3 ions′ places in which it posited center position of c axis. With the increase of Eu2O3 content, the position of the strongest emission peak changed from 540 nm (5D1→7F2 transition) to 626 nm (5D0→7F2 transition), and the maximum intensity was obtained when x=0.09 in Y2O2S∶Eu3 x(0.01≤x≤0.10). This is due to the environment of trivalent europium in the crystal structure of Y2O2S. Doping with Mg2 or Ti4 ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg2 and Ti4 ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd*m-2). Thus the LLP mechanism was analyzed.     

Gd3+,Eu3+在介孔Y2O3中的能量传递

通过模板法与溶胶-凝胶法相结合,在温和的条件下制备了介孔Y2O3.再采用水热反应法制得Eu3+、Gd3+单掺杂及Eu3+,Gd3+双掺杂的三种介孔Y2O3组装体(介孔Y2O3∶Eu3+,介孔Y2O3∶Gd3+,介孔Y2O3∶Eu3+,Gd3+).利用广角和小角X射线衍射(XRD)、透射电子显微镜(TEM)对介孔Y2O3进行了表征,结果表明,所制备的介孔Y2O3为立方相,具有六方孔道结构,孔径约10nm.对介孔Y2O3和组装体系进行了荧光光谱(PL)分析,发现在550℃热扩散处理后,介孔Y2O3∶Eu3+的发光存在基质对Eu3+的能量传递,Y2O3∶Eu3+,Gd3+体系中Gd3+对Eu3+也有能量传递作用.     

Preparation,Structural Analysis and Luminescence Properties of Nanocrystalline Phosphor Gd2O3∶Eu

Nanocrystalline monoclinic and cubic Gd2O3∶Eu with different Eu3 concentration were prepared using glycine-nitrate combustion synthesis. By changing the ratio of glycine to nitrate and proper heat treatment, pure monoclinic and cubic Gd2O3∶Eu with particle size less than 40 nm can be easily formed. Under ultraviolet excitation, main emission of Eu3 (5D0→7F2) locates at 624 nm in monoclinic Gd2O3∶Eu and 611 nm in cubic sample. In excitation spectrum two broad bands corresponding to the host absorption and charge transfer state(CTS) and f-f transitions of Gd3 and Eu3 were observed and discussed. The quenching concentration of monoclinic and cubic Gd2O3∶Eu is 10% and 15%, respectively, both of which are much higher than that of bulk Gd2O3∶Eu.     

(Sr1-xMx)Al2O4(M=Ca,Ba)∶Eu发光材料的研究

以SrAl2O4∶Eu发光材料为基础,通过对基质的部分修饰,合成了(Sr1-xMx)Al2O4(M=Ca,Ba)∶Eu磷光体,并利用XRD对其晶体结构进行了研究,结果表明:加入Ca后,原来在室温下稳定存在的属于单斜晶系的鳞石英结构SrAl2O4相逐渐变成六方晶系,证明Ca有稳定六方相的作用,而加入Ba晶形则不发生改变。同时研究了该发光粉的发射光谱,讨论了Ca和Ba的引入对发光性能的影响。     

Luminescence and Energy Transfer Properties of Ca_2Gd_8(SiO_4)_6O_2∶A(A=Pb~(2 ), Tm~(3 ))Phosphors

Compoundswiththeapatitestructureareverysuit ablehostlatticesforvariousluminescentions .ThemostwellknownexampleisSb3 andMn2 coactivatedcalci umhalophosphateCa5(PO4 ) 3(F ,Cl)∶Sb ,Mn ,whichhasfoundapplicationsinfluorescentlampsforalongtime[1] .Ca2 R8(SiO4 ) 6 O2 (R =Y ,Gd ,La)isakindofternaryrare earth metalsilicatewiththeoxyapatitestructure ,whichhasbeenusedashostmaterialsfortheluminescenceofvariousrareearthandmercury likeions[2～ 4 ] .Themostprominentstructuralcharacteristicisthetwos…     

Synthesis of Long Afterglow Phosphors MAl_2O_4∶Eu~(2 ), Dy~ (3 )(M=Ca, Sr, Ba) by Microemulsion Method and Their Luminescent Properties

LongafterglowphosphorsMAl2O4∶Eu2 ,Dy3 (M=Ca,Sr,Ba)haveattractedmuchinterestsfrom1990sowingtotheirexcellentpropertiessuchaslight andheatendurance,chemicalstability,highlumines centintensity,longafterglowtime,containingno poi sonouselementandsoon[1～6].Tra…     

Synthesis and luminescence properties of a novel phosphor Ca2–x/2Si1–xPxO4:Eu2+for near UV-excited white-light-emitting diodes

A novel green-emitting phosphor,Eu2+-doped Ca2-x/2 Si1-x Px O4(0.25≤x≤0.30),was prepared through a conventional solidstate reaction.X-ray diffraction(XRD),photoluminescence(PL) and decay studies were employed to characterize the sample,which was assigned to P63mc space group in the hexagonal system.The effect of P-doping on the α-Ca2 SiO4 was studied and P2 O5 broken down by the raw material of(NH4)2 HPO4 played an important role in stabilizing α-Ca2 SiO4 which can only be stable at high temperature.The XRD patterns of the Ca2-x/2 Si1-x Px O4 host were found pure and optimized when the mole fraction of P2 O5 was 14.5%.The diffuse reflectance spectra of the Ca1.855 Si0.71 P0.29 O4 and Ca1.845 Si0.71 P0.29 O4 :0.01Eu2+covered the spectral region of 230-400 nm,implying that the phosphor was suitable for UV or near-UV LED excitation.The phosphor could be effectively excited in the near UV region with the maximum at 372 nm.The emission spectrum of the Ca1.845 Si0.71 P0.29 O4 :0.01Eu2+phosphor showed an asymmetrical single intensive band centered at 513 nm,which corresponded to the 4f65d1→4f7transition of Eu2+.Eu2+ions might occupy two types of Ca2+sites in the Ca1.855 Si0.71 P0.29 O4 lattice and form two corresponding emission centers,which led to the asymmetrical emission of Eu2+in Ca1.855 Si0.71 P0.29 O4.The effects of Eu2+-doped concentration in Ca1.855-x Si0.71 P0.29 O4 :xEu2+on the PL were also discussed,the optimum doping concentration of Eu2+was 1 mol.% and the critical distance of the energy transfer was also calculated by the concentration-quenching method.The non-radiative energy transfer between Eu2+seemed to be caused by the multipole-multipole interaction.The fluorescence lifetime of Eu2+was found to be 0.55711 μs.The results suggested that these phosphors might be promising candidates used for near UV light excited white LEDs.     

Syntheses and Crystal Structure of Nine-Coordinate Mononuclear Na[ EuⅢ (edta)(H2O)3] · 4H2O and Binuclear Na4[Eu2Ⅲ(Httha)2]·10H2O Complexes

The crystal and molecular structures of the Na[Eu Ⅲ (edta) ( H2 O) 3] · 4H2O ( edta = ethylenediaminetetraacetic acid) and Na4[Eu2Ⅲ (Httha)2] · 10H2 O ( ttha = triethylenetetraminehexaacetic acid) complexes were determined by single-crystal X-ray structure analyses.The crystal of Na[ EuⅢ (edta) (H2O)3] · 4H2O belongs to orthorhombic crystal system and Fdd2 space group.The crystal data are as follows: a = 1.9415 (15)nm, b = 3.544(3 )nm, c = 1.203(9)nm, V = 8.327(5)nm3, Z = 16, M = 589.27, Dc= 1.880 g· cm-3, μ= 3.108mm-1 and F(000) = 4704.The final R and wR values are 0.0312 and 0.0750 for 2091[I ＞ 2.0σ (I)] reflections, and 0.0344and 0.0766 for all 3932 unique reflections, respectively.The[EuⅢ (edta) (H2O) 3] - anion has a nine-coordinate pseudo-monocapped square antiprismatic structure in which the nine coordinate atoms, two N and seven O, are from one edta ligand and three water molecules.The crystal of Na4[Eu2Ⅲ (Httha)2] · 10H2O belongs to orthorhombic system and Pccn space group.The crystal data are as follows: a = 2.610(3)nm, b = 2.089(3)nm, c = 2.239(3)nm, V =12.208 ( 28 ) nm3, Z = 8, M = 1548.92, Dc= 1.686g·cm-3,μ = 2.115 mm-1andF(000) = 6272.Thefinal R and wR are 0.0625 and 0.1091 for 9834[I ＞ 2.0σ(I)] reflections, and 0.1608 and 0.1471 for all 37818 unique reflections, respectively.The whole complex molecule is composed of two close parts in which each one has a nine-coordinate structure with distorted monocapped square antiprismatic prism.The ttha ligand in the[Eu2Ⅲ (Httha)2] 4- anion coordinates to one Eu Ⅲ ion with three N atoms and four O atoms and to the other Eu Ⅲ ion with two O atoms.     

Investigations on Valence-Change Behaviors of Europium Ions in Eu-Doped Aluminate and Silicate Phosphors

Compounds of Sr3Al2O6∶Eu, Sr4Al14O25∶Eu, and BaZnSiO4∶Eu were synthesized by high-temperature solid state reactions. The doping Eu3 ions were partially reduced to Eu2 in Sr4Al14O25∶Eu and BaZnSiO4∶Eu prepared in an oxidizing atmosphere, N2 O2. However, such an abnormal reduction process could not be performed in Sr3Al2O6∶Eu, which was also prepared in an atmosphere of N2 O2. Moreover, even though Sr3Al2O6∶Eu was synthesized in a reducing condition CO, only part of the Eu3 ions was reduced to Eu2 . The existence of trivalent and divalent europium ions was confirmed by photoluminescent spectra. The different valence-change behaviors of europium ions in the hosts were attributed to the difference in host crystal structures. The higher the crystal structure stiffness, the easier the reduction process from Eu3 to Eu2 .     

Sr_2MgSi_2O_7∶Eu,Nd体系中Eu~(2+)向Nd~(3+)的能量传递

通过高温固相法合成了Sr2MgSi2O7∶Eu2+,Nd3+发光材料,测试了样品的物相结构、可见和近红外激发和发射光谱、荧光寿命等,研究了Eu2+对Nd3+的近红外发光性能的影响及近红外发光相对强度变化的规律,考察了煅烧温度、煅烧时间对近红外发光性能的影响。结果表明,1200℃下煅烧的Sr2MgSi2O7∶0.02Eu2+,0.01Nd3+样品近红外发光强度最强,Eu2+对Nd3+的近红外发光敏化效果最好。证实了在Sr2MgSi2O7∶Nd3+,Eu2+体系中Eu2+通过无辐射传递的模式向Nd3+有效传递了能量。