低热导率碲化物热电材料的制备及性能优化

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1、浙江大学硕士学位论文1．37，性能提高了10％左右。(5)．制备了(Gel．xPbxTe)ss(Ago．6Sbl．4Te2．4)15(沪0．2，0．24，0．28，O．32)系列含Pb的TAGS．85材料。实验发现，Pb含量小于28％样品中有(GePb)Te2次相，大于28％样品中次相则5勺(GePb3)Te4。固溶Pb后材料仍然能保持优异的电学性能，而材料的晶格热导率和总热导率却不至lJ(GeTe)s5(Ago．6Sbl．4Te2．4)15基体材料的二分之一。(Geo．8Pbo．2Te)85(Ago．6Sbl．4Te2．4)15样品具有最高Z丁值，在750K达到1．57，比本课题组前期

2、得到的(GeTe)85(Ago．6Sbl．4Te2．4)15的样品Z产1．35性能提高了20％左右。关键词：热电材料；A98GeTe6；GeTe—AgSbTe2；碲化物；低热导率Thermoelectric(TE)materialshavepromisingapplicationsinrefrigerationandpowergenerationfortheabilityofdirectthermal—electricalenergyconversion．Mostoftheresearchestodayfocusonthereductionofthermalconductivityint

3、heTEmaterials谢tllllighelectricaltransportproperties．Therearefewreportsabouthowtoimproveelectricaltransportpropertieswhilemaintainingthebeneficialthermalpropertiesoflowthermalconductivitymaterials．Inthispresentwork，twokindsoflowthermalconductivitythermoelectricmaterialsAgsGeTe6and(GeTe)ss(AgSbTe2)

4、15werechosen．Doping，nonstoichiometryandsolidsolutionwereperformedonthetwosystemstoimprovetheTEproperties．Theconclusionsarelistedbelow：(1)．TheAgself-dopedAgs吖GeTe6(萨0，O．008，0．016，0。032)bulkmaterialswereprepared．Theverylowthermalconductivitiesof<0．26Wm。1K．1wereobserved，comparablewiththeamorphouslim

5、itation．TheAgdeficiencyroughlyledtotheincreasedSeebeckcoefficient．Amaximum刀valueof0．4Wasobtainedataround570Kforx=0．008．(2)．TheSbdopedAgsGeSbxTe6-x@=0，0．012，0．024，0．060)bulkmaterialswereprepared．ThematerialissensitivetothenonstoichiometryofTeandtraceTelossledtotheprecipitationofsecondphaseA92Te．Th

6、ematerialiss仃engthend．SbsubstitutedGebutnotTeunexpectedlywhichdecreasedtheelectricalconductivity．TheSeebeckcoefficientvariesobviouslywi廿1differentSbdopingamount．TheZTvaluedecreasedafterSbdoping。(3)。TenonstoichiometricAgsGeTe细舻O，O．12，0．24)andAgsGeTe撕舻0，0．12，0．24，O．60)bulkmaterialswereprepared．InTe

7、losscase，AgETewasalsopresent．AstheTelossamountincreased，theelectricalconductivitydecreasedandthesignoftheSeebeckcoefficienttumedfrompositivetonegative．TheZTvalueofx=0．12improvedabout30％duetoitsclosepowerfactorbuta20-30