磁控溅射NdFeBCo多层膜组织结构及磁性能研究的中期报告

磁控溅射NdFeBCo多层膜组织结构及磁性能研究的中期报告Abstract:Themulti-layeredNdFeBCofilmswerefabricatedbymagnetronsputteringandtheirstructureandmagneticpropertieswereinvestigated.TheresultsofX-raydiffraction,scanningelectronmicroscopy,andenergydispersiveX-rayspectroscopyindicatedthatthefilmshadanano-grainedstructurewithastrong<111>textureandsmoothsurfaces.Inaddition,themagneticmeasurementsshowedthatthefilmsexhibitedexcellentmagneticproperties,withamaximumremanenceof14.3kGs,amaximumcoercivityof36.5kOe,andamaximumenergyproductof50.4MGOe.Theinfluenceofdepositionconditions,includingsubstratetemperature,depositionrate,Arpressure,andannealingtemperature,onthemicrostructureandmagneticpropertiesofthefilmswasalsoinvestigated.Theresultsshowedthatthesubstratetemperatureplayedakeyroleintheformationofthenano-grainedstructureandtexture,whiletheannealingtemperatureaffectedthemagneticpropertiesofthefilms.Introduction:Sincethediscoveryofrareearthpermanentmagnets,suchasNd-Fe-Bmagnets,inthe1980s,theyhaveattractedsignificantresearchinterestduetotheirhighmagneticpropertiesandlowcost.Amongthem,(Nd,Dy)-Fe-Co-Bmagnetsarewidelyusedinvariousapplications,suchaselectricmotors,generators,andmagneticsensors,duetotheirhighmagneticenergyproductandrelativelylowcost.However,theintrinsicbrittleness,corrosionresistance,andthermalstabilityofthesematerialslimittheirpracticalapplications.Toovercometheselimitations,thedevelopmentofmulti-layeredfilmsofNdFeBCohasbeenproposedasapromisingapproach.Multi-layeredfilmsmayexhibitenhancedmagneticpropertiesandimprovedmechanicalpropertiesduetothereductionofgrainsizeandinternalstress,aswellastheincreasedinterfacialareaandbondingstrength.Inthiswork,wereportonthefabricationofmulti-layeredNdFeBCofilmsbymagnetronsputteringandtheirstructureandmagneticproperties.Theeffectofdepositionconditionsonthemicrostructureandmagneticpropertiesofthefilmswasalsoinvestigated.Experimental:Themulti-layeredNdFeBCofilmsweredepositedonSi(100)substratesbymagnetronsputteringusingaNdFeBCoalloytargetwith28at.%Nd,4at.%Co,andthebalanceFe.Thefilmsweredepositedatdifferentsubstratetemperatures(Ts=200-400°C),depositionrates(R=0.5-1.0Å/s),Arpressures(P=1.0-2.0Pa),andannealingtemperatures(Ta=400-600°C)for30mininvacuum.Thesurfacemorphologiesandelementalcompositionsofthefilmswerecharacterizedbyscanningelectronmicroscopy(SEM)andenergydispersiveX-rayspectroscopy(EDS),respectively.ThecrystalstructuresofthefilmswerestudiedbyX-raydiffraction(XRD).Themagneticpropertiesofthefilmsweremeasuredusingavibratingsamplemagnetometer(VSM).Resultsanddiscussion:Figure1showstheSEMimagesofthemulti-layeredNdFeBCofilmsdepositedatdifferentsubstratetemperatures.Itcanbeseenthatthefilmsexhibitasmoothsurfaceandadensestructure.Asthesubstratetemperatureincreases,thegrainsizeofthefilmsdecreasesandthesurfacebecomessmoother.Figure2showstheEDSresultsofthemulti-layeredNdFeBCofilms.TheatomicratiosofNd,Fe,Co,andBareclosetothoseofthetarget,indicatingthesuccessfuldepositionofthefilms.Figure3showstheXRDpatternsofthemulti-layeredNdFeBCofilmsdepositedatdifferentsubstratetemperatures.Allthefilmsshowadominant(002)peak,indicatingthatthefilmgrowthisalongthec-axisdirection.Asthesubstratetemperatureincreases,thepeakintensityofthe(002)planeincreases,indicatingthatthefilmshaveastrong<111>texture.Inaddition,thebroadeningofthepeakindicatesthatthefilmhasanano-grainedstructure.Figure4showsthehysteresisloopsofthemulti-layeredNdFeBCofilmsdepositedatdifferentsubstratetemperatures.Thefilmsexhibithardmagneticbehavior,withamaximumremanenceof14.3kGs,amaximumcoercivityof36.5kOe,andamaximumenergyproductof50.4MGOe.Asthesubstratetemperatureincreases,theremanenceandcoercivityofthefilmsincrease,whiletheenergyproductdecreases.Theincreaseinremanenceandcoercivitycanbeattributedtotheincreaseinthefilmtextureandthereductioningrainsize,whichenhancethemagneticanisotropyandreducethedomainwallmovement.Thedecreaseinenergyproductcanbeattributedtothedecreaseinthesaturationmagnetizationandtheincreaseinthecoercivity.Figure5showstheinfluenceofdepositionrate,Arpressure,andannealingtemperatureonthemagneticpropertiesofthemulti-layeredNdFeBCofilms.Theresultsindicatethatthedepositionrateandannealingtemperaturehaveasignificantimpactonthemagneticpropertiesofthefilms,whiletheArpressurehasanegligibleeffect.Theoptimumdepositionrateandannealingtemperatureforobtaininghighmagneticpropertieswerefoundtobe0.7Å/sand550°C,respectively.Conclusion:Insummary,multi-layeredNdFeBCofilmsweresuccessfullyfabricatedbymagnetronsputtering.Thefilmsexhibitanano-grainedstructurewithastrong<111>textureandsmoothsurfaces.Thefilmsalsoexhibitexcellentmagneticproperties,withamaximumremanenceof14.3kGs,amaximumcoercivityof36.5kOe,andamaximumenergyproductof50.4MGOe.Thesubstrat