Revisiting the Temperature Dependent Ionic Conductivity of Yttria Stabilized Zirconia (YSZ)

By C. Ahamer, A. Opitz, G. Rupp, Juergen Fleig. 2017

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The temperature dependent conductivity of yttria stabilized zirconia (YSZ) exhibits a bending in Arrhenius’ plots which is frequently discussedintermsoffreeandassociatedoxygenvacancies.However,theveryhighdopingconcentrationinYSZleadstosuchastrongdefectinteractionthattheconceptoffreevacanciesbecomeshighlyquestionable.Therefore,thetemperaturedependentconductivityofYSZisreconsidered.TheconductivityofYSZwithdifferentdopingconcentrationwasmeasuredinabroadtemperaturerange.ThedataareanalyzedintermsoftwodifferentbarrierheightsthathavetobepassedalonganaveragepathofanoxygenvacancyinYSZ(twobarriermodel).For8–10mol%yttria,thetwobarriersareintherangeof0.6eVand1.1–1.2eV,respectively.Theconductivityandthusthebarrierheightsalsodependonthecoolingrateafterahightemperaturepre-treatment.Thisindicatesthatdifferentfrozen-indistributionsofdopantsaffectthevacancymotionbydifferentenergylandscapes.Temporarilyexistingdefectconﬁgurations,possiblywithastrongeffectofrepulsiveoxygenvacancyinteraction,aresuggestedasthereasonofhighbarriers.Futuredynamicab-initiocalculationsmayrevealwhetherthismodiﬁedmodeloftheYSZconductivityismechanisticallymeaningful.©TheAuthor(s)2017.PublishedbyECS.ThisisanopenaccessarticledistributedunderthetermsoftheCreativeCommonsAttribution4.0License(CCBY,http://creativecommons.org/licenses/by/4.0/),whichpermitsunrestrictedreuseoftheworkinanymedium,providedtheoriginalworkisproperlycited.[DOI:10.1149/2.0641707jes]Allrightsreserved. stabilized zirconia (YSZ) is among the most important ion conducting solids and acts as a kind of model material representing fast oxide ion conductors. Owing to this model character of YSZ, but also due to its application in solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs) and oxygen sensors, a vast amount of papers can be found dealing with its oxide ion conduction. The ionic conductivity is based on the motion of oxygen vacancies, introduced by Y 3 + ions replacing Zr 4 + . For concentrations above ca. 8 mol%, yttria doping also stabilizes the cubic structure down to room temper- ature. A detailed review of the science of YSZ and related materials

Subfields: Catalysis, Materials Chemistry

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