bi2te3热电材料压缩与剪切性能的分子动力学分析word格式论文.docxVIP

AbstractThermoelectricmaterialisakindofnewfunctionalmaterial,andcanachieve directconversion between heatandelectricity.Thermoelectricdevicesaregreen,safe, andreliable,whichhaswideapplicationprospects.Inallkindsofthermoelectric materials,Bi2Te3isthefirstthermoelectricmaterialwhichhasalreadybeenusingin thecommercialapplication.Intheserviceenvironmentofthethermoelectricdevice, thethermoelectricmaterialisinevitablyinthelong-termcyclicloading,whichwill leadtothedeclinedmechanicalstabilityandfurtherleadtothefailureofthe thermoelectricmaterial.Thus, studyofmechanical propertiesofBi2Te3 thermoelectricmaterialisimportantforitsindustrialapplication.Compressionand shearpropertiesofBi2Te3areinvestigatedtorevealtheeffectofVanDerWaals BondingonmechanicalpropertiesofBi2Te3,providinganimportanttheoreticalbasis fordevelopingthe highlyefficientand stableBi2Te3thermoelectric devices.Alongthecaxisofcrystallattice,Bi2Te3 hasperiodicquintuplelayers“-Te1-Bi-Te2-Bi-Te1-”whichareconnectedbyVanderWaalsbonding.Inthispaper, themoleculardynamicsmethodhasbeenemployedtostudythemechanical properitesofcuboidsingle-crystalbulkBi2Te3undercompressiveandshearloads. TheemphasisareputontheeffectsoftheVanderWaalsbondingonthedeformation andfailuremechanism.TheresultsshowthattheVanderWaalsbondingplaysa dominantroleonthemechanismofdeformation,andfundamentallydeterminesthe compressiveultimatestressandfracturestrain.Furthermore,compressiveloadalong andperpendiculartothecaxiscanleadtoquitedifferentfailuremodes,whichcanbe distinguishedbytheirspecificeffectsonthedeformationoftheVanderWaals bonding.However,onlymodelswiththecompressiveloadperpendiculartothecaxis dramaticallydemonstratethestrainrateeffectonthestress–straincurves,just accordingtoitspoorstructuralstability.Differentfromcompression,itisevidentto findthestrainrateeffectinalltheshearmodelsbecauseoftheeasyslipofVander Waalsbonding,whichmayalsohintthepossibilityofbrittle-ductiletransition. Obviously, much more work should be done on the modification of mo