A density functional study of defect migration in gadolinium doped ceria.pdf

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1、ViewArticleOnline/JournalHomepage/TableofContentsforthisissuePAPERwww.rsc.org/pccp

2、PhysicalChemistryChemicalPhysicsAdensityfunctionalstudyofdefectmigrationingadoliniumdopedceriaPratikP.Dholabhai,*JamesB.Adams,PeterCrozierandRenuSharmawReceived23rdNovem

3、ber2009,Accepted25thMarch2010FirstpublishedasanAdvanceArticleontheweb26thMay2010DOI:10.1039/b924534kOxygenionconductivityofdopedceriaisobservedtobetwo-threeordersofmagnitudehigherthanyttriastabilizedzirconia,themostwidelyusedsolidelectrolytematerialatt

4、emperaturesbelow6001C.Gadoliniumdopedceria(GDC)isknowntobeoneofthemostpromisingsolidelectrolytematerialsforoperationofsolidoxidefuelcellsbelow6001C.TounderstandtheatomicdefectmigrationinGDC,wehaveusedtotalenergycalculationswithintheframeworkofdensityfu

5、nctionaltheorytofollowoxygenvacancymigrationinGDC.WereportactivationenergiesforvariousoxygenvacancymigrationpathwaysinGDC.Oxygenvacancyformation3+andmigrationwereevaluatedforfirst,second,andthirdnearestneighborpositionstoaGd3+4+ion.Duetothecomparableion

6、icradiiofGdandhostCeions,thefirstnearestneighborsitewithrespecttothedopantcationisfoundtobethemostfavorableoxygenvacancyformationsite.Themigrationpathwaywherethevacancymigratesfromasecondtofirstnearestneighborisfoundtobemostfavorable.Thecalculatedactivat

7、ionenergiesforoxygenvacancymigrationinGDCarecomparedagainstthereportedmeasuredandcalculatedvaluesfromtheliterature.ThisworkwillprovideafoundationforthedevelopmentofakineticlatticeMonteCarlomodelforvacancydiffusioninGDC,whichwillimprovetheunderstandingof

8、oxygenionconductivityindopedceria.1.Introductionmajorattentionduetoitspossibleapplicationsastheanode1,2,4–7materialwithinsolidoxidefuelcells(SOFC).Applica-SolidOxideFuelCells(SOFC)operableinanintermediatetionsinthreewaycatalysttechnologyarealsodependen

9、tupontemperaturerange(500–8001C)aregaininginterestcomparedoxygenmobility,sincetheoxygenuptake/releaseprocessmusttohightemperatureSOFCsduetoseveraladvantagessuchasfastnecessarilyinvolveadiffusionstepfromthesurfacetobulkstartup/shutdown,hi