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1.IntroductionCrystallinealignmentinmaterialscanbecontrolledbyimpositionofahighmagneticfield.Thisprinciplecanbeappliedtonon-magneticmaterialswithasymmetricunitcells.1–11)Whenmaterialsareplacedinamagneticfield,thecrystalsexhibitinganisotropicmagneticsusceptibilityori-entthemselvestothedirectionofthemaximumsusceptibil-ityparalleltothemagneticfield.Inthisreviewpaper,theprincipleisdescribedandthere-centdevelopmentofthemagneticcrystallinealignmentofinorganicmaterialsissummarized.2.ThePrincipleofMagneticCrystalOrientationWhenanon-magneticsubstanceismagnetizedinamag-neticfield,theenergyformagnetizationofthesubstanceUisgivenbyEq.(1).......................(1)whereMisthemagnetization,BandBintheimposedmag-neticfluxdensityandthemagneticfluxdensityinthesubstance,respectively,m0thepermeabilityinvacuum(4p107[H/m]).Theprincipletocontrolthecrystallinealignmentusingamagneticfieldisthatamagnetictorquerotatescrystalstotakethestablecrystallinealignmentsoastodecreasethemagnetizationenergy.Letusconsideracrystalofthehexagonalstructurewithamagneticanisotropy,thatis,themagneticsusceptibilityisdifferentineachcrystaldirection.Thevalueofthemagne-tizationenergygivenbyEq.(2)thatisderivedfromEq.(1),determinesthepreferredcrystaldirectiondependingonthemagneticsusceptibilityofeachcrystalaxis............(2)whereccandca,barethec-axisanda-orb-axisofamag-neticsusceptibility,respectively.qtheanglebetweenthedirectionsofamagneticfieldandthec-axisofacrystal.Whenccca,b,i.e.UcUa,b,thec-axisofcrystalsisthepreferredaxisinparalleltothedirectionofthemagneticfield.Incontrast,whenccca,b,i.e.UcUa,b,thea-orb-axisofcrystalsisthepreferredaxisinparalleltothemag-neticfield.Thatis,thec-axisofcrystalsalignstoallofthedirectionsintheplaneperpendiculartotheimposedmag-neticfield.3.MagneticCrystallineAlignment3.1.SizeClassification12)Inacolloidalprocess,thecrystallinealignmentisgreatlyaffectedbyBrownianmotionforceandgravityforce,andeachdominantregionislargelydependingonparticlesize.Foralargecrystal,thegravityforcemustbetakenintocon-sideration,whiletheBrownianmotionforcecanbeig-nored.Andwhenaparticleissmall,thesituationisviceverse.Whenahighmagneticfieldisapplied,theeffectiveparticlesizerangeforthecrystallinealignmentcanfurtherbeclassifiedasfollows:1)wheretheBrownianmotionismoreactivethanthegravitymotion.Thatis,duringalignmentofcrystallineparticlessizedinthisrange,wedonotneedtoconsiderthegravityforcebutonlymagneticfieldeffect.3224380232227(),minrkTBrrkTeg≡≡µπχηπρρρ∆cripplUBBabcabχµχχµθ,,()cos22022022UMdBB000in/(/)µµ∫519©2007ISIJMagneticCrystallineAlignmentShigeoASAILaboratoryofElectromagneticProcessingofMaterials,DepartmentofProcessingEngineering,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603Japan.(ReceivedonDecember28,2006;acceptedonFebruary5,2007)Anewtechnologyrelatingtocrystallinealignmentandtexturecontrolhasemergedbythedevelopmentofsuperconductingtechnologies.Itsprinciplebasedonmagnetizationforcecanbeappliedtonon-magneticmaterialswithasymmetricunitcells.Inthispaper,theprincipleisdescribedandtherecentdevelopmentofthemagneticcrystallinealignmentofinorganicmaterialsissummarized.KEYWORDS:magneticcrystallinealignment;highmagneticfield;electromagneticprocessingofmaterials;materialsprocessing.ISIJInternational,Vol.47(2007),No.4,pp.519–522Review2)wherethegravityforceismoreactivethanBrownianmo-tionforce.Inotherwords,bothofthegravityforceandmagnetizationforceshouldbetakenintoconsideration.3.2.SlipCastingFormagneticcrystallinealignment,thefollowingthreeconditionsarerequired13):(1)crystalshaveananisotropicmagneticsusceptibilityand(2)existinaweaklycon-strainedmedium,and(3)thecrystalsizeisinasuitablerangeasmentionedinSec.3.1.Thefunctionofdifferentkindofmagneticfieldsisgiveninthefollowings.3.2.1.StaticMagneticFieldAnovelprocesswhereahighstaticmagneticfieldisim-posedduringslipcastingwasproposedtofabricatehighlycrystal-orientatedceramics.14,15)Letusdefinethemagneticfieldswhichareimposedinparallelandperpendiculartothedirectionofslipcasting,asPaandPemagneticfields,respectively.Thesurfacesoftop,side1andside2inaspecimenaredefinedasFig.1.WhenthePamagneticfieldisimposed,theside1andside2be-comesamesothattheyrefertothesidesurface.Whenthegravityforcecanbeneglected,theexpectedcrystallinealignmentofmaterialsinaslipcastingunderthePeandPamagneticfieldsisgiveninTable1.Inthistable,a,bandcindicatethecrystallineplanesofmaterials.Itcanbeseenthatifccca,b,itisrelativelyeasytogetahighcrystallinealignmentbecauseofnofreedominthec-axisdirection.IfthePemagneticfieldisimposed,thetopandside1surfacesshowthea,bplaneandtheside2surfacedoesthecplane.IfthePamagneticfieldisimposed,thetopsurfaceshowsthecplaneandtheothersdothea,bplane.Incontrast,ifccca,b,itisdifficulttogetthehighcrystallinealignmentbecauseofthefreedominthec-axisdirection.IfthePemagneticfieldisimposed,thea,bandcplanesappearinthetopandside1surfaces,althoughthea,bplanewhichdistributesrandomlyappearsontheside2surface.IfthePamagneticfieldimposed,thea,bandcplanesappearonthebothsidesurfacesandrandomlydistributeda,bplaneap-pearsonthetopsurface.3.2.2.RotatingMagneticFi