简介:对锂离子电池(LIB)正极材料尖晶石LiMn2O4和LiCoO2与LiBF4作溶质电解液的匹配性进行了研究。用X射线衍射法(XRD)对正极材料的结构进行了表征,采用循环伏安法测定了电解液的氧化分解电位,将充放电试验与傅里叶变换红外光谱测试(FTIR)相结合考察了LiMn2O4和LiCoO2与电解液的匹配性。结果表明:LiMn2O4对电解液的匹配性都很好,其第三循环放电容量(D3)最高可达122.1mAh/g。而LiCoO2对电解液则有一定的选择性:与LiBF4/EC+DMC(1∶1)匹配性较好,而与另两种的匹配性则很差,D3仅为73.9mAh/g、53.3mAh/g;FTIR测试表明充放电过程中LiCoO2表面与这两种电解液发生了激烈的反应。
简介:ThesinglecrystalgrowthofstoichiometrichostluminescentcrystalNa5Eu(WO4)4hasbeeninvestigated.UsingNa2WO4asaflux,theoptimumconditionstogrowapuresinglecrystalbyflux-slow-coolingmethodhavebeendetermined.Ahighopticalqualitysinglecrystalofdimention4.5mmhasbeengrown,whichisthelargestoneasweknowsofar.Themicro-hardnessofNa5Eu(WO4)4singlecrystalis3.46×103MPa.Itsrefractiveindexis1.81inwhitelightwavelengthregionandthespecificgravityis5.65g/cm3.Thefluorescentandexcitationspectrahavebeendeterminedandthereasonofthefluorescentquenchof5D2and5D1to7FjofEu3+canbeexplainedasmulti-phononnon-radiationtransition.
简介:ThephotoluminescencepropertiesofBiTaO4∶Pr3+andBiTaO4atroomtemperaturewerestudied,andtheinfraredtransmissionanddiffusionreflectionspectraofBiTaO4weremeasured.ThephotoluminescencespectrumofBiTaO4peaksatabout420,440and465nm.Therehasanobviousexcitationbandfrom330to370nm.ThephotoluminescencespectrumofBiTaO4∶Pr3+consistsofthecharacteristicemissionofPr3+,anditsmainpeakisat606nmfrom3P0→3H6transitionofPr3+.Itsexcitationspectrumconsistsofthewidebandwithmaximumat325nm,thewidebandintherangeof375~430nm,andthecharacteristicexcitationofPr3+.Thebandsat325nmand375~430nmmaybefromtheabsorptionofthechargetransfertransitionofthetantalategroupanddefectenergylevelsinitsforbiddenband,respectively.ThereisenergytransferfromhosttoPr3+.BecauseboththehostdensityandphotoluminescencepeakintensityofBiTaO4∶Pr3+aresuperiortoPbWO4,BiTaO4∶Pr3+maybeapotentialheavyscintillator.
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简介:Ca8Mg(SiO4)4Cl2:Eu2+phosphordopedwithSr2+cationforCa2+partially,wassynthesizedbysolid-statereactionathightemperatureunderreducingatmosphere,anditsluminescentpropertieswereinvestigated.TheexperimentalresultsindicatethattheemissionintensityofthephosphorincreasesafterbeingdopedwithafewamountofSr2+ion.Theemissionpeakofthephosphorblueshifttoabout464nmwhenthephosphorisdopedwithlargequantityofSr2+ions.TheexcitationspectrumindicatesthatthephosphorcanbewellexcitedbyUVandbluelightfrom300to460nm,andthephosphorwasfittedwellfortheexcitationbyUVorblue-LED.
简介:Trivalentdysprosium(Dy3+)activatednanocrystallineyttriumvanadate(YVO4)phosphorwassynthesizedviaco-precipitationmethod.ThepreparedsampleswerecharacterizedbyX-raydiffraction(XRD),Fouriertransforminfraredspectroscopy(FTIR),scanningelectronmicroscopy(SEM),opticalabsorptionandphotoluminescence(PL)techniques.TheXRDpatternsrevealthetetragonalcrystallinephase.SEMimagesrevealthatDydopedYVO4nanocrystalsareagglomerated.EDAXconfirmstheformationofYVO4:Dy.FTIRspectrumshowstwostrongabsorptionbandsat459and761cm-1.Opticalabsorptionspectrumshowedthesurfacedefectsintheas-preparedsamples.ThePLemissionspectrumshowstwocharacteristicemissionbandsat485and575nm.Thestrongyellowemissionpeakat575nmisassignedto4F9/2→6H13/2hypersensitivetransitionofDy3+ions,StudyofCIEchromaticitydiagramindicatesthesuitabilityofthephosphorforthedevelopmentofyellow-greenLEDs.
简介:TheextractionofCe(Ⅳ)inH2SO4/H3PO4systemwasinvestigatedsystematicallyusingbifunctionalionicliquidextractants(Bif-ILES)[A336][P507],[A336][P204]and[A336][C272]inn-heptane.TheeffectsofH2SO4concentration,extractantconcentrationandsalting-outagentconcentrationwereobservedindetail.TheextractionmechanismofCe(Ⅳ)inH2SO4/H3PO4systemwasobtained.ThecomparisonwithotherextractantssuchasCyanex923,TBPwasalsostudied.Thermodynamicfunctionsoftheextractionreactionwerecalculated,showingthattheextractionwasanexothermicprocess.TheseparationofCe(Ⅳ)fromRE(Ⅲ)andTh(Ⅳ)wasalsoinvestigated.TheresultindicatedthatCe(Ⅳ)couldbeselectivelyextractedinthissystem.CePO4nanoparticleswereobtainedintheprocessofstrippingusingH2O2inH2SO4/H3PO4system.X-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andspectroscopywereadoptedforthecharacterizationofthesample.