简介:DirectextractionofmetalsfromsolidswithcomplexingagentsinsupercriticalCO2(SC-CO2)hasrecentlyattractedinterestsinseparation,purification,recovery,andanalysisofmetals.Inthepresentstudy,thestatic/dynamicextractionofrareearthelements(Nd,Ce)fromtheiroxides(Nd2O3,CeO2)withorganophosphoruscomplexeswithHNO3andH2OinSC-CO2wasinvestigated.ThestaticextractionefficiencyofNdfromNd2O3withthetri-n-butylphosphate(TBP)-HNO3complexcouldreach95%underoptimizedexperiment...
简介:Thesinglecrystalofthecomplex[Sc(NO3)3(H2O)2]·(15C5)hasbeenpreparedinacetonitrile.Thenewcomplexhasbeencharacterizedbyelementalanalysis,IRspectra,solubilityandmolarconductancemeasurements.ThestructureofthecomplexisdeterminedbysinglecrystalX-raydiffractionanalysis.
简介:NanosizedBaCeo.95Yo.o5O3-δpowderswiththehomogeneouscompositionweresynthesizedbyanewcombustionprocessbasedonthePechinimethod.Apolymericprecursorsolwasformedbyuseofcitricacidandethyleneglycolasthechelatingagentsofmetalions.Theperovskite-typeBaCeo.95Yo.o5O3-δpowderswithuniformshapeandsmallerthan40nminsizedwereobtainedthroughthecombustionofthepolymericprecursorsolattheexistenceofnitricacidandammoniumhydroxide.Itwasfoundtheparticlesizecouldbecontrolledbymodulatingthequantitiesofnitricacidandammoniumhydroxide,thequantitiesoftheresidue,carbonateionswerealsoaffectedbythequantitiesofthecitricacidandethyleneglycol.
简介:TheZrO2-Al2O3ceramiccompositeswerepreparedbyappropriatetechniqueswithcommercialZrO2andAl2O3powdersasrawmaterialsandY2O3asstabilizer.TheresultsindicatethatwiththeintroductionofAl2O3intotheZrO2matrixwherethequantityofadditiveY2O3is3.5%(molefraction),thegrowthofZrO2grainsisefficientlyinhibited,whichhelpstheZrO2grainsexistinametastabletetragonalmanner;thushigherstrengthandtoughnessareacquired.Whenthecontentofaluminais20%(massfraction),thebendingstrengthandfracturetoughnessofthecompositesare676.7MPaand10MPa·m1/2respectively,themechanicalbehaviorsareclosetothosepreparedwithZrO2andAl2O3powderssynthesizedthroughwetchemicalapproach.Themechanicalbehaviorsofthecompositesarewellimprovedowingtothedispersiontougheningofaluminagrainsandphasetransformationtougheningofzirconiagrains.
简介:基于国外定向凝固氧化物/氧化物共晶复合陶瓷的晶体生长动力学行为的研究成果,阐述其动力学机制,分析动力学因素对微观结构形态的影响,探讨晶体生长热力学、动力学行为与微观结构形态之间的关系,同时结合以燃烧合成、快速凝固技术制备的新型高强韧A12O3/ZrO2(Y2O3)共晶复合陶瓷,探讨共晶复合陶瓷在快速凝固条件下的晶体生长动力学行为。结合定向凝固与快速凝固两种晶体生长机制,得知过冷度、凝固界面前沿的温度梯度是影响晶体生长方式的重要因素,且受二者决定的凝固速率(即晶体生长速率)则决定材料的最终微观结构与形态。
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.
简介:为了减少锂离子电池正极材料与电解液的相互作用,用沉淀法在LiNi0.8Co0.2O2表面包覆一层Al2O3,并通过电化学测试、扫描电镜和X射线衍射研究其表面形貌和晶体结构。结果表明,经过表面包覆后,有效地抑制了电解液对正极材料的侵蚀,虽然初始放电容量略有降低,但循环性能明显改善;Al2O3包覆量对LiNi0.8Co0.2O2电化学性能存在影响,包覆量为0.7%(质量分数)的样品性能最优。
简介:以六水合氯化钴(CoCl2·6H2O)和水合三氯化钌(RuCl3·3H2O)为前驱体,采用胶体法制备超级电容器用(RuO2/Co3O4)·nH2O复合薄膜电极材料。用X射线衍射仪以及CHl660C电化学工作站对该复合薄膜的物相结构及电化学性能进行表征。结果表明:当COCl2'6H20和RuCl3·3H2O的物质的量比n(Co):n(Ru)为2:1时,于350℃下热处理2.5h制备的复合薄膜电极具有优良的性能,在浓度为0.5mol/L的H2S04电解液中其比电容达到512F/g,500次充放电循环后比电容量保持在充放电循环前的96.1%;充放电电流为0.01A时,内阻为1.2Ω。
简介:Inthiswork,boththethermalexpansionandelectricalconductivityofnanocrystallineLa2Mo2O9werestudied.ThenanocrystallinepowderofLa2Mo2O9wasobtainedbysol-gelmethod,andwiththehelpofSHP(superhighpressure)upto4.5×104atmat700℃forashorttime,andthenanocrystallinepowderwasdensifiedwithoutobviousparticlesizegrowth.TheelectricalconductivityofnanocrystallineLa2Mo2O9wasoneorderofmagnitudelowerthanthatofthemicrocrystallinesampleatthesametemperature.Owingtothephasetransition,themicrocrystallineLa2Mo2O9hasanabruptincreaseofthermalexpansionwithapeakvalueof48×10-6K-1at556℃.Forthenanocrystallinematerial,thepeakvalueincreasesto112×10-6K-1at520℃.Ontheotherhand,above600℃thesignificantgrowthofparticlesizeofthenanocrystallineLa2Mo2O9wasobserved,accompanyingbyatremendousincreaseofthermalexpansionwithapeakvalueofthirdhigherthanthatofLa2Mo2O9.
简介:Heterogeneousprecipitationmethodwasusedtopreparedsurfacecoatingonself-madeBaMgAl10O17:Euphosphor.Resultsillustratethatthecoatingfilmcanbesilicondioxideinamorphousstatewith50nminthickness.Photoluminescenceresultsindicatethatthecoatinglayerpresentsanobservableimprovedeffectontheenhancementofthermalstability.Whenbakedat600℃for1h,theluminanceofcoatedBAMkeepsat92%higherthanthatofuncoatedBAMby23%.ThisprotectiveeffectcanbeattributedtothehighcompactdegreeanduniformityofthisamorphousSiO2coatingfilmwhichisservedasadiffusionblocklayertoinbreakoxygenatom,thusreleasestheoxidationextentofEu2+effectively.