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纳米晶MnZn功率铁氧体烧结工艺及液相掺杂机理研究.docx

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纳米晶MnZn功率铁氧体烧结工艺及液相掺杂机理研究 摘要： 本文研究了纳米晶MnZn功率铁氧体的烧结工艺以及液相掺杂机理。首先，通过将气相沉积和高温固相反应相结合的方法制备出了一种MnZn纳米晶铁氧体，具有高强度、高饱和磁通密度和低损耗等优点。然后，运用热重分析、X射线衍射、扫描电子显微镜和电子探针等手段详细地研究了纳米晶MnZn铁氧体的烧结工艺，并探讨了影响烧结过程的各种因素。最后，我们对纳米晶MnZn铁氧体进行了液相掺杂，进一步改善了其性能。 关键词：纳米晶MnZn铁氧体；烧结工艺；液相掺杂机理 Introduction MnZnferriteshavebeenwidelyusedinpowerapplicationduetotheirhighpermeability,highQ-factorandlowcoreloss.Inrecentyears,withthedevelopmentofnanotechnology,nanocrystallineMnZnferriteshavebeenreceivedmuchattentioninpowerapplicationsbecauseoftheirhighmagneticinduction,lowcoercivity,andhighresistivity.However,thesinteringprocessofnanocrystallineMnZnferriteismoredifficultthanthatofconventionalMnZnferrites,becauseofitshighersurfaceareaandlargersurfaceenergy. Therefore,itisnecessarytoinvestigatethesinteringprocessofnanocrystallineMnZnferriteandexploretheliquidphasedopingmechanismtoimproveitsproperties. Experimentalprocedure TheMnZnnanocrystallineferritewaspreparedbyacombinationofgas-phasedepositionandhigh-temperaturesolid-statereaction.Thespecificpreparationprocessisasfollows:first,MnZnmixedpowderwaspreparedbyaddingMnO,ZnOandFe2O3powdersaccordingtothestoichiometricratio.Then,themixedpowderwassinteredat1200°Cfor12hoursinavacuumfurnacetoobtainMnZnferriteprecursor.Subsequently,theprecursorwascrushedandgroundintonanometer-sizedpowderbyballmilling. ThenanocrystallineMnZnferritewasdensifiedbytwo-stepsinteringprocess.Thefirstsinteringstepwascarriedoutat1100°Cto1250°Cfor1hourtodensifytheparticles,andthesecondsinteringstepwascarriedoutat1300°Cfor3hourstoobtainthefinalbulkstructure.ThedensificationbehaviorofnanocrystallineMnZnferritewascharacterizedbythermogravimetricanalysis(TGA),X-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andelectronprobemicroanalyzer(EPMA). TheliquidphasedopingwascarriedoutusingCo,Ni,Zn,andCuasdopants.Thedopantswereaddedtotheprecursorpowderandmixedbyhigh-energyballmilling.Themixturewasthensinteredandcharacterizedasmentionedbefore. ResultsandDiscussion TheXRDpatternsofthenanocrystallineMnZnferrites