Propositum
Usedtomanufacturehomotropicmagneticsteel,magneticfilm,andtoys.
Crystalcharacteristicsofbariumferrite
Bariumferrite(BaFe12O19) isahardThemagneticmaterialbelongstotheM-typemagnetoplumbite,whichisarelativelysimplemagnetoplumbiteferritewithhexagonalsymmetryandbelongstothehexagonalcrystalsystem.Itscrystalstructureisdifferentfromspinelferrite,becauseitcontainsbarium(Ba)andlead(Pb)plasma,anditsradiusissimilartooxygenions(1.32nm),soitcannotenterthegapformedbyoxygenionsItsradiusissimilartothatofoxygenion(1.32nm)andcanonlybeinthesamelayerwithoxygenion.Itscrystalstructureisnotcubicsymmetrybuthexagonalsymmetry.Thesymmetryofthehexagonalcrystalislowerthanthatofthehexagonalcrystal,soitsmagnetocrystallineanisotropyisextraordinarilylarge.EachBaFe12O19unitcellincludestwomolecules,whichcanbedividedinto10oxygenionlayers.Theclose-packedarrangementofoxygenionsinthec-axisdirectioncanbedividedintoseverallayersandblocks.TheoxygenionlayerincludingBa2+iscalledthebariumlayerandisrepresentedbyB1.ThisB1layerappearseveryfouroxygenionlayers.EachB1layerincludesaBa2+,3Fe3+,ofwhich2occupiestheBpositionandoneoccupiesthesix-sidedpositioncomposedoffiveoxygenions,AlsoknownasEposition.
Theimportanceofmagnetoplumbite-typeferriteisthatithascertaincharacteristicsduetoitscrystalsymmetrythattheothertwotypesofferriteswithcubicsymmetrydonothave.
Praeparationmethodofbariumferrite
Becausebariumferriteiswidelyusedinpermanentmagneticmaterialsandperpendicularrecordingmaterials,ithassmallsyntheticparticlesize,uniformchemicalcompositionandhighperformanceThebariumferriteultrafinepowderisthemaindirectionofmagneticmaterialsresearchnowadays.Therearemanymethodsforsynthesizingbariumferriteultrafinepowder,themainmethodsare:co-precipitation,hydrothermalcrystallization,metalorganichydrolysis,glasscrystallization,organicresin,sol-gel,andspraypyrolysisWait.
Summary
Nanomagnetictechnologyisthedominanttechnologyinthefirst20yearsofthiscentury.Nanomagneticmaterialsarethecoreofnanomagnetictechnology.Itisthemostpromisingmaterialinthe21stcenturyandalsonanomagnetic.Oneofthefoundationsoftechnologyapplication.Thedevelopmentofnano-magnetictechnologyhasbroughtmajoropportunitiesandchallengesforthetraditionalmagneticindustrytodevelopbyleapsandbounds.Thedevelopmentandresearchofnano-scalemagneticmaterialsisaninevitabledirectionforthedevelopmentofmagneticmaterials.Researchonnano-magneticmodificationofexistingmaterialsinordertocomprehensivelyimprovethetechnicallevelandcompetitivenessofenterprises,andestablishthebanneroftheChinesenationamongthenationsoftheworld.