简介:Inordertorealizetheco-firingwithAg/Pdelectrodesinmultilayerdevices,Pb(Zn1/3Nb2/3)1-,-yZrxTiyO3(0.25<x<0.35,0.25<y<0.35)piezoelectricceramics(hereafterdesignatedPZN-PZT)modifiedbyLa2O3hasbeenpreparedbyconventionaltechniquewithsinteringtemperaturefrom1100℃to1140℃.X-raydiffractionpatternsdemonstratedthatpureperovskitephasewasobtained.Secondaryelectronimage(SEI)showedthatcrystallinegrainsinceramicswerewellgrown.d33ofmanufacturedsamplewasashighas560×10-12C/N.kpwasabout0.61andtgδabout30×10-3.TheexistenceofliquidphaseexaminedbyelectrondiffractioninPZN-PZTsampleisbeneficialtosinteringoftheceramic.
简介:以3种煤沥青为研究对象,采用元素分析、平均分子量、核磁共振氢谱(1H—NMR)以及红外光谱分别对其进行表征和分析,使用改进Brown-Ladner法对煤沥青的结构参数进行计算,并构建出各煤沥青的平均分子结构模型。结果表明,煤沥青的基本结构单元是稠环芳烃连接烷基侧链并含杂原子,结构单元之间形成缔合体,缔合数为5~9。3种煤沥青的烷基侧链都很短,且均不包含环烷烃。构建的分子模型为煤沥青提供了形象的化学结构,有助于从分子水平加深对其认识和研究。
简介:WithFe(NO3)39H2OandBi(NO3)35H2Oasrawmaterials,differentsillenite-typecompoundsandelementalbismuthwerepreparedbyafacileone-potsolvothermalmethodusingH2O,C2H5OH,(CH2OH)2andC3H8O3assolvents,respec-tively.Thestructure,morphology,elementalcompositionsandpropertiesofsampleswereexaminedbyXRD,SEM,TEM,ICP,XPS,N2adsorptionanddesorption,UV-visDRSandPL.ThephotocatalyticactivitiesofdifferentsampleswereevaluatedbythephotodegradationofRhBundervisible-lightirradiation(λ>400nm),andresultsshowthatBi36Fe2O57preparedusingC2H5OHasthesolventownstheoptimumperformance.Inordertoexplorethereactionmechanism,anadditionalexperimentwasdesignedtoinvestigatethemainactivespeciesduringthephotodegradationprocessviadissolvingdifferenttrappingagentsinthereactionsolutionbeforelightirradiation.TheresultsshowthatsuperoxideradicalanionsplayamajorroleinthissystemsincetheRhBdegradationwassignificantlysuppressedaftertheadditionofbenzoquinone.