Ba,6-3xSm,8+2xTi,18O,54高介电常数微波介质陶瓷及其改性

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1、塑兰查竺!主竺竺兰奎二兰竺一一AbstractBa6．3xLn8+2xTil8054solidsolutionsarethetypicalhigh．emicrowavedielectricinmicrowavecommunicationceramics，whichhaveveryimportantapplicationstechn0109yasthekeymaterialsformicrowaveresonatorsandfilters．Inthisthesis，andeffectsofcompositionandsinteringcondition

2、suponthemicrostructuresmicrowavedielectriccharacteristicsofBa6-3xSms+2xTil8054solidsolutionwereinvestigated．ModiflcationofmicrostructuresandmicrowavedielectricpropertieswereconductedbyNdsubstitutionforSmintotheA·site．SnsubstitutionforTiintotheB—siteandNd／SncosubstitutionforSm厂r

3、iintotheA—andB—sitesintheBa6．3，Sma+2，TiIs054solidsolution．Inaddition，properlyprolongingsinteringwaseffectivetoimprovemicrowavedielectricproperties．Phaseconstitution，microstructuresanddielectricpropertiesofBa6．3xSms+2xTits054ceramicswereinvestigatedasfunctionsofcompositionandsin

4、teringcondition．Thesolidsolutionlimitswereconfirmedtobe0

5、propertiesdecreasedwithincreasingfrequencysincethecontributionfromsuchtemperaturesensitivepolarizationmechanismsbecameweaker．Atmicrowavefrequencies，dielectricconstantdecreasedwithincreasingXduetotheshrinkageofTi06Octahedralsite．Ofvalueincreasedfirstandthendecreased，withthehighe

6、stvalueatx=2／3．whereSmionsandBaionsareorderedintherhombicsitesandpentagonalsites．respectively．Near—zerotrvaluecouldbeachievedinthesedielectrics．EfkctsofcompositionandsinteringconditionsuponthemicrostructuresandthemicrowavedielectriccharacteristicsofBa6．3x(Sml．vNdv)8+2xTil8054so

7、lidsolution(x=2／3)wereinvestigated．Thedielectricconstantincreasedandthetemperaturecoefncientofresonantfrequency17fcouldbeadjustedfromnegativetopositivewithincreasingNdcontentinthesolidsolution，whilethehi曲Qffactor(>9，000GHz)wasobtained．Itshouldbeemphasizedthatthetemperaturetoemc

8、ientofresonantfrequencywassignificantlyaffectedbysinte