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点缺陷对β--FeSi2基热电材料结构与性能影响的第一性原理研究.docx

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点缺陷对β--FeSi2基热电材料结构与性能影响的第一性原理研究 Title:First-PrinciplesStudyontheImpactofPointDefectsontheStructureandPropertiesofβ--FeSi2-basedThermoelectricMaterials Introduction: Thermoelectricmaterialshaveattractedsignificantattentionduetotheirabilitytodirectlyconvertwasteheatintousableelectricpower.Amongvariousthermoelectricmaterials,β--FeSi2hasemergedasapromisingcandidateforhigh-temperatureapplicationsduetoitsexcellentthermoelectricproperties.However,understandingtheinfluenceofpointdefectsonthestructureandpropertiesofβ--FeSi2iscrucialforoptimizingitsthermoelectricperformance.Inthispaper,wepresentafirst-principlesstudyontheimpactofpointdefectsonthestructureandpropertiesofβ--FeSi2-basedthermoelectricmaterials. Methods: First-principlescalculationsbasedondensityfunctionaltheory(DFT)areemployedtoinvestigatetheeffectsofpointdefectsontheelectronicstructure,latticeparameters,thermalconductivity,andelectricaltransportpropertiesofβ--FeSi2.TheViennaAbinitioSimulationPackage(VASP)isusedfortheDFTcalculations,andthegeneralizedgradientapproximation(GGA)isemployedtotreatexchange-correlationeffects. ResultsandDiscussion: 1.ElectronicStructure:Wefirstexaminetheelectronicstructureofβ--FeSi2inthepresenceofpointdefects.Specifically,weconsidervacancies,interstitials,andsubstitutionaldefectsinvolvingdifferentelements.Ourcalculationsrevealthatpointdefectsinducelocalizedelectronicstateswithinthebandgap,leadingtochangesintheelectronicpropertiesofβ--FeSi2.Thedensityofstates(DOS)analysisprovidesinsightsintotheroleofpointdefectsinmodifyingtheelectronictransportproperties. 2.LatticeParameters:Theimpactofpointdefectsonthelatticeparametersofβ--FeSi2isinvestigated.Itisfoundthatvacancies,interstitials,andsubstitutionaldefectscaninfluencetheatomicpositionsandbondlengths,resultinginlatticedistortions.Moreover,thepresenceofpointdefectscanalsoaffectthestabilityofβ--FeSi2,asindicatedbythecalculatedformationenergies. 3.ThermalConductivity:Pointdefectscanscatterphononsandtherebyreducethethermalconductivityofβ--FeSi