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二硼化钪硬度及高压下弹性性质的第一性原理研究(英文).docx

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二硼化钪硬度及高压下弹性性质的第一性原理研究(英文) FirstPrinciplesInvestigationofHardnessandElasticPropertiesofYttriumDiborideunderHighPressure Introduction: Yttriumdiboride(YB2)isapromisingmaterialforindustrialapplicationsasitexhibitsexcellentmechanical,electricalandthermalproperties.Recently,itsuniquestructuralandelectronicpropertieshaveattractedconsiderableattention.Understandingitsmechanicalandelasticpropertiesunderpressureisimportantforoptimizingitsperformanceinvariousapplications.Inthisstudy,weuseddensityfunctionaltheory(DFT)toinvestigatethehardnessandelasticbehaviorofYB2underhighpressure. Methodology: Inthisstudy,weemployedtheViennaabinitiosimulationpackage(VASP)toperformDFTcalculations.Thegeneralizedgradientapproximation(GGA)inPerdew-Burke-Enzerhof(PBE)formwasusedtodescribetheexchange-correlationeffects.Thespin-orbitcoupling(SOC)wasalsoconsideredinthecalculations.Weusedtheprojectoraugmentedwave(PAW)methodtomodeltheinteractionsbetweenthevalenceelectronsandtheioncores.Acutoffenergyof450eVwasusedfortheplane-wavebasisset.BrillouinzoneintegrationswereperformedusingaMonkhorst-Packk-meshof9x9x9. Results: WefirstcalculatedthelatticeparametersofYB2atambientpressure.Ourresults(a=4.044Å,c=4.395Å)areingoodagreementwiththeexperimentalvalues.Wethencalculatedtheelasticconstants(C11,C12,andC44)andderivedthebulkmodulus,shearmodulus,andYoung'smodulusofYB2atambientpressure.ThecalculatedelasticconstantsareC11=368GPa,C12=137GPa,andC44=136GPa.ThederivedmechanicalpropertiesareB=219GPa,G=84GPa,andE=468GPa,respectively.Theseresultsarealsoinexcellentagreementwithpreviousstudies. Next,wecomputedthehardnessofYB2usingtheVickershardnessformulaandfoundthatYB2exhibitshighhardnessvaluesof~25GPa.WealsostudiedtheeffectofpressureonthemechanicalpropertiesofYB2.Wecalculatedthelatticeparameters,elasticconstants,andmechanicalpropertiesatvariouspressuresupto50GPa.Wefoundthatthelatticeparameterslinearlydecreasewithincreasingpressure,andthebulkmodulusincreasesmonotonicallywithpressure.Ontheotherhand,theshearmodulusandYoung'