新型鈷基氧化物YCoO-,3-體系制備與熱電性能研究.pdf

1、中國科學(xué)院合肥物質(zhì)科學(xué)研究院博士學(xué)位論文新型鈷基氧化物YCoO體系制備與熱電性能研究姓名：劉義申請學(xué)位級別：博士專業(yè)：凝聚態(tài)物理指導(dǎo)教師：秦曉英20070501摘要FabricationandThermoelectricPropertiesofCobasedOxideYC003SystemAbstractInthethesis，novelCobased—oxideYC003systemWaspreparedbysolgelprocess

2、followedbyhigh—temperaturesinteIing，andtheeffectofdopingonitselectricaltransportandthermoelectriepropertiesweresystematicallyinvestigatedThemainresultsincluded：1Thermalandelectricaltransportpropertiesofalkalineearthmetal

3、dopedcompoundsYIxRxC003(R=CaSrBa)wereinvestigatedsystematicallyExperimentsrevealedthatuponheavydopingofCaMort’SlnpocTI／4lawappearedatlowtemperatures，indicatingoccurrenceofvariablerangehoppingconductionMoreoverbecauseofCa

4、2substitutionforY3holecarrierconcentrationincreasedgreatlywhichresultedindecreaseofelectricalresistivityandthermalconductivityandconsequentlyremarkableimprovementofhightemperaturethermoelectricpropertiesInadditionbycompa

5、risonwefoundthatitsthermoelectricpropertiescouldbeenhancedmuchmoreeffectivelybydopingofCawithsmallerionicradiusHoweverwefoundthathigh—temperatureSeebeckcoefficientofalltheY1xRxC003compoundsapproachedalimitvalue～150ItV／Ka

6、t～800K，indicatingthattheirhigh—temperaturethermopowermainlycamefromtheconfigurationentropyofCo一3delectrons2ThecompoundsYC01xMx03(M=Cr’Mn，F(xiàn)e，NiandMo)withsubstitutionoftransitionelementsforCositewerefirstpreparedsuccessful

7、lyandtheirhigh—temperaturethermoelectricpropertieswereinvestigatedsystematicallyItWasfoundthatitspowerfactorwasimprovedinthetemperaturerangefrom300Kto720KbyNidopingInterestinglyanovelphenomenonWasobservedintheMn(orMo)lig

8、htlydopedcompound：Seebeckcoefficientofthedopedcompound(s)possessedverylargenegativemagnitude(570“wi()，beingincontrasttopositivevalueforYC003，whoseunderlyingmechanismwasdiscussed3ThesynthesisofZn，Ag，BiandPbdopedYC003compo