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1、MaterialsScience-Poland,Vol.24,No.1,2006Somestructuralaspectsofionicconductivityinzirconiastabilisedbyyttriaandcalcia*M.M.BUĆKOAGHUniversityofScienceandTechnology,FacultyofMaterialsScienceandCeramics,al.Mickiewicza30,30-519Cracow,PolandNanopowderswithnominalconst
2、antoxygenvacancyconcentrationsof8,10,and12mol%werepreparedintheternaryZrO2–CaO–Y2O3system.Theconstantoxygenvacancyconcentrationswereob-tainedbyincorporatingcalciaandyttriaintozirconiasolidsolutionsatdifferentratios.TheRietveldrefinementmethodwasusedtocharacterise
3、thestructuralchangesinthezirconiasolidsolution.X-raydiffractionanalysiswasalsousedtocharacterisethephasecompositionofthesamplesandlatticepa-rametersofthecubicphase.Thefour-probemethodwasappliedfordeterminingelectricalpropertiesofthesamples.Theconductionproperties
4、ofthesampleswerecharacterisedwithrespecttotheirstructuralfeatures.Keywords:zirconia;ionicconductivity1.IntroductionFullystabilizedcubiczirconiahasbeenactivelyinvestigatedasanoxideioncon-ductorinsolidoxidefuelcells(SOFC),oxygensensors,orelectrochemicaloxygenpumps[
5、1,2].Consequently,severalapproacheshavebeentakentoimprovetheelec-tricalpropertiesofzirconiamaterials.Structuralmodificationofcubiczirconiaisoneofpromisingwaystoamelioratetheionicconductivityofzirconia-basedelectrolytes.Theionicconductivityofzirconiasolidsolutions
6、(s.s.)isstrictlyrelatedtotheionicradiusandvalencyofcationsincorporatedintothezirconiastructure[3,4].Itiswellknownthatforfluorite-structureoxidestheconductivityisoptimisedbymatchingthesizeofthedopantandstructuralions[5].Aspecialformofionsiteinstabilityoccurs,howev
7、er,whenacompoundisonthevergeofatransitionbetweentwophases,oneofwhichisaslightdistortionoftheother.Insuchacase,anunstablestructureshouldhaveitsmaximumionicconductivityattheminimumstabilizingdopantconcentration_________*Correspondingauthor,e-mail:bucko@uci.agh.edu.
8、pl40M.M.BUĆKO[6].Structuralstressandtheformationofcomplexdefects(e.g.,ahostordopantcationwithanoxygenvacancy)shouldalsobetakenintoconsiderationwhenexplain-ingt
