硅烯材料上原子吸附的第一性原理分析

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1、AbstractAdsorbingforeignatomsonsilicenehassignificanteffectonthepracticalapplications.Theadsorptionofmetalatomsprovidesaroutetomodifytheelectronicpropertiesofsilicene.Furthermore,theadsorptioncharacteristicoflithiumonsilicenealsoprovidesaguaranteeforsi

2、liceneasananodeoflithiumionbattery.However,theadsorptionanddiffusionofmetalatomsonsilicenearealwaysaffectedbyvariousenvironments,suchasstrainandhydrogenation.Motivatedbythis,inthisthesiswestudytheadsorptionanddiffusionofatomsonthesilicenewithdifferente

3、nvironmentsbyusingthefirst-principlesplane-wavepseudopotentialmethod.Ourworkismainlydividedintotwoparts:(1)StructuresandenergiesofLi-adsorbedsiliceneunderabiaxialstrainarestudied.Accordingtotheoptimizedstructures,theLi-adsorbedsilicenebasicallykeepthei

4、roriginalconfigurationswithoutdistortionwhenensileandcertaincompressivestrain(ε≥-4%)areapplied,whilethesiliceneplanebulgestowardstheLiatomwhenalargercompressivestrain(ε=-4.5%or-5%)isapplied.Itisfoundthatimaginaryfrequenciesappearinthephononspectrawhent

5、helargecompressivestrainsareappliedonsilicene.Theresultsofphononspectraindicatethattheinstabilityofsiliceneunderthecompressivestrainresultsinthesignificantdistortionofsiliceneafterthelithiumadsorption.(2)Adsorptionanddiffusionofalkalimetalatoms(Li,Na,K

6、)andalkaliearthmetalatoms(Be,Mg,Ca)onhydrogenatedsilicenearestudied.Andtheresultsofhydrogenatedsilicenearecomparedwiththoseofperfectsilicene.Ourcalculationsshowthatfortheatomsconsideredinourwork,theadsorptionenergiesonhydrogenatedsiliceneislargelysmall

7、erthanthoseonsilicene.Thediffusionenergiesofthealkalimetalatomsonsiliceneisinsensitivetothestatusofsilicene,namelyhydrogenatedorperfect.However,thediffusionenergiesofthealkaliearthmetalatomsonhydrogenatedsiliceneisalsosignificantlysmallerthanthoseonsil

8、icene.Keywords:silicene;strain;first-principles;adsorption;phononspectrumII目录摘要................................................................................................................................................IAbstract....