MA-SPS制备CoSb_,3_和RE_,x_Co_,4_Sb_,12_的热电性能及其(5)

时间:2025-07-06

北京工业大学工学博士学位论文

thetemperaturerisingandhavedimensionlessthermoelectricfigureofmeritZTlessthan0.0571.

CexC04Sbl2thermoelectricmaterialswerepreparedbyMA—SPSforthefirsttime,thedependenceoftheirthermoelectricpropertieswithtemperatureandCecontentwereinvestigatedsystemicallyandtheeffectsofLa,CeandNdonthermoelectricpropertiesofRExC04Sbl2sampleswerecompared:(1)DopedCemakestheresistivitydecreasetoalowermagnitudeandincreaseselectricconductingpropertygreatly;TheresistivitiesofsamplesdecreasewiththeCecontentincreasingwhenx20.7~2.0.theincreasingCecontentdoesnotevidentlydecreasetheresistivitywhenx>1.25;(2)Thesampleswithpositive甜arePtypewhenx=0.1,O3and0.5andthehigherCecontentsampleswithnegative口arentypewhenx=0,7~2.O;(3)ThethermoelectricpowerfactorsofCe。C04Sbl2getthemaximumof15.30~23.70×10。4wK~m~at100~500。Cwhenx=1.25;(4)Ce05C04Sbl2hasthelowestthermalconductivityof1,922~1.609Wm‘1K-1at100~500。ClowerthanthatofCoSb3inthesamegroup.ThethermalconductivityofCe20C04Sbl2isseveraltimesthanthoseofthelowerCecontentsamplesandmoreCedopedmakesthethermalconductivityincrease;(5)ThehighestZTfigureofptypeis0.1739at500。Cwhenx=0.5;TheZTfiguresofntypeCexC04Sbl2(x20.7~2.0)increasefirstandthendecreasewiththeCecontentincreasing,Whenx=1.0itgetsthehighestfiguresof01675~0.374-at100~500℃inwhichthemaximumiSO.374at400℃thatiSthehighestZTfigureinntypesamplesandalsointheexperimentsofthispaper.(6)PhasesaresimilarinRF,xC04Sbl2withthesameREcontent(La,Ce,orNd)respectivelyandCel0C04Sbl2hasthehighestZT,ItisshownthatCeistheoptimumdopedelementandx=1.0istheoptimumCecontentintheexperimentalconditionsofthispaper.

CoSb3andCexC04Sbl2sinteredatthetemperature650℃havethesameaveragecrystalgrainsizeobservedbyTEM,thereforerareearthelementCedoesnotchangetheircrystalgrainsizesSOthattheeffectofcrystalsizeonthermalconductivityshouldbeonthesamelevel;ResultsofneuronandX—raydiffractionfittedbytheRietveldmethodshowthatonlyasmallquantityofCeatomswerefilledincrystalcellvoidsofCexC048b12andtheeffectofCeelementsismainlyⅣ

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