International Center of Condensed Matter Physis
Universidade de Bras
ilia
Bras
ilia - Brazil - September, 11 - 15, 2000
Chairpersons: ReginePerzynski (U.P.M.C.-Paris,Frane)
FranisoA.Tourinho (UnB-Bras
ilia,Brazil)
Organizingommittee:
Jer^omeDepeyrot (UnB-Bras
ilia)
MariaC.F.LimaeLara (UnB-Bras
ilia)
GeraldoJ.daSilva (UnB-Bras
ilia)
AntonioM.FigueiredoNeto (USP- S~aoPaulo)
JoseA.Miranda (UFPe-Reife)
HansD. Pfannes (UFMG-BeloHorizonte)
ClaudioSherrer (UFRGS-PortoAlegre)
Magneti uids (MF) are stable olloidal solutionsof magneti nanopartiles dispersed in a arrierthat an
be either a polar or a non-polar liquid. This arrier an also be a more omplex system, suh as a polymeri
solution, agel, ora liquid rystal. These materials are of interest for both hemists and physiists. Thanks to
theunusualassoiationbetweenthemagnetiandtheuidpropertiesofthearrier,theexperimentalisthasathis
disposal apowerfulexternalparameter,themagnetield. Thisis theoriginalfeature ofthe MFwith respet to
ordinaryuids. Thestrengthofthisexternalparameterleadstonumerousandvariousappliations,fromrotating
shaftsin theharddisksystemofmiroomputerstoassisteddampersoftrukseatsandoptialshutters ofmissile
pointers. All thesetehnialappliationsbringupalotofnewproblems. Averyativeommunityoftheoretiians
has undertakenthe taskto takle theseproblems. Conformationalinstabilities, whih leadto peaks,labyrinthine
patternsormagnetistarshes,aregoodexamplesofspei MF.
MFdonotexistinnature. Tobestableataolloidallevel,andtopreventtheagglomerationofthenanopartiles
undervanderWaalsmagnetidipolarinterations,itisneessarytoinvokeaertaindegreeofinterpartilerepulsion
inside theolloidal solution. This repulsion is either steri oreletrostati. It is produed either by asurfatant
oatingofthenanopartilesorbyasuperialdensityofeletrostatiharge. Thesematerialsarethustheprodut
of sophistiated olloidal syntheses. They have also apromising future in biohemial, biophysial and medial
appliations. They an be used as a drug arrier, as a ontrast agent in magneti resonane imaging, and in
magneto-thermaltherapiesofsomeaners.
Workson magnetiuidshavebegunin theUSAinthe earlysixties,withthe inventionofthese materialsby
ProfessorRonaldE.Rosensweigin theontextofaspatialprogram. Sinethen,theinternationalommunitythat
workswiththeseuidsystemshasbeengrowingregularly,inludingsientistsbelongingtothewesternworld(and
Japan)andtotheformerSovietUnion. Everythreeyears,largeonferenesbringtogetherthewholeinternational
ommunity. The main poles of researhonMF are loatedin the USA(California,Florida, Massahusets,
Penn-sylvania), Japan (Akita, Kyoto, Sendai, Tokyo), western Europe(Frane,Germany, Ireland, Netherland,Norway,
Spain,UnitedKingdom),easternEurope(Hungary,Latvia,Romania,Russia,Slovakia),Brazil,andIndia.
In Brazil, the MF ommunity extends all overthe ountry at dierent states (Bras
ilia, Goias, Minas Gerais,
Parana,Pernambuo,RiodeJaneiro,RioGrandedoSul,S~aoPaulo). Thisommunityinludeshemists,physiists
andbiophysiists. Theorganizationofaone-weekmeeting inBrazilappearsasanexeptionalopportunityforthe
whole Brazilian MF ommunity to gettogether and to establishloseontatswith theforeigninvited leturers.
The Workshop on Magneti Fluids hasbeen organizedby Prof. Regine Perzynski (U.P.MC., Paris,Frane) and
Prof. FranisoA.Tourinho(UnB,Bras
ilia,Brazil)inBras
ilia,fromSeptember11to15,2000. Itadoptedaformat
of one-hour presentations, allowing theletures to be detailed and pedagogial. Inthis respet, it was held in a
learlydierentspiritfrom theinternationalMFonferenes.
All the 26 oral presentations were invited talks (12 from Brazil, 14 from outsideBrazil). The followingnine
foreignsientistshavegiveoralpresentations: MihaelWidom,Pittsburgh,USA,BalahandranJeyadevan,Sendai,
Japan,StefanOdenbah,from Bremen,Germany,Jean-ClaudeBari,EmmanuelleDubois,andRegine Perzynski,
havebeenanelledat thelast moment(wearesorrythat RonaldRosensweig,from theUSA,and RosangelaItri,
fromBrazil,ouldnotattendthemeeting). ThereweretwelveBrazilianinvitedspeakers: Jer^omeDepeyrot,JoelC.
Rubim,andFranisoA.Tourinho,fromBras
ilia,BismarkV.daCosta,P.Liinio,andHans-DieterPfannes,from
BeloHorizonte,LuizR.Evangelista,fromMaringa,Parana,JoseA.Miranda,fromReife,ConstantinoTsallis,from
RiodeJaneiro,ClaudioSherrer,fromPortoAlegre,andAntonioM.FigueiredoNetoandHerilioR.Rehenberg,
from S~aoPaulo. A postersession hasbeeninluded,withabriefpresentationof the20postersontherstdayof
theworkshop.All theposterappliationstotheworkshophavebeenaepted,allowinganyonetopartiipateand
to presenthisownsientiwork.
TheWorkshoponMagnetiFluidswasheldintheInternationalCenterofCondensedMatterPhysisinBras
ilia.
TheCenterhasprovidedaveryprofessionalassistane. Inpartiular,wethankProf. HugoNazareno,hairmanof
theCenter,forallhis supporttothesientiandtehnialorganizationofthemeeting.
Weheartily thankallthe sponsorsthat haveprovidedtheorganizingommittee withnanialsupportto the
workshop,namely,theBrazilianageniesCAPES-COFECUB,CNPq,FAPDF,FUBRA,theAmbassadedeFrane
and, veryspeially, Prof. LauroMorhy,Retorof theUniversityofBras
ilia. Wealsodeeplythankallthereferees
fortheirworkwithoutwhihtheseproeedingsouldnothaveappeared.
Fromasientipointofviewthesopeoftheonfereneanbedividedintovedierentthematiparts:
-Nanopartilesynthesis. Twodierentkindsofsynthesiswerepresentedanddisussed: (i)hemialsynthesis
of ioniMF (E. DuboisandF. Tourinho); (ii)mehanialsynthesisbyball milling(H. R. Rehenberg); 3posters
wererelatedtothistopi.
-Colloidal stability, struture and rheology. There were severalexperimental worksusing various
teh-niques, suhassmallangleneutronsattering(E.Dubois),statianddynamiallightsattering(B.Jeyadevan,P.
Liinio),rheologialmeasurements(S.Odenbah)toprobetheexistene,dependingoftheexperimentalsituation,
ofthree-dimensionalstruturesinsidetheolloid. Struturesintheviinityofawallell,duetothewettingofthe
MF,werealsodisussed(A.FigueiredoNeto). MonteCarlosimulations(B.daCosta)gaveasupplementaryvision
oftheloalstruturesthatMFmaydevelopinanappliedeld;2postersand3artileswererelatedtothesepoints.
-Magneti properties - statis and dynamis. Experimental studies usingvarious tehniques havebeen
presented: magnetization measurements, Mossbauer spetrosopy, and Raman spetrosopy. They have given a
good insight into the internal struture of nanopartiles (J. Depeyrot, H-D Pfannes, H. R. Rehenberg , and J.
Rubim). Several theoretial works were direted to enlighten thedesription of magneto-dipolar systemsfrom a
thermostatistialpointofview(Yu. Raikher,C.Sherrer,C.Tsallis,andM.Widom)andtoaddressheatandmass
transferproperties(E.Blums); 8postersand8artileswererelatedtothesetopis.
-2D-patternsandinstabilities. Theinterestingtopiof2D-patternsinHele-Shawellsinamagnetieldwas
illustratedbyseveraltheoretialtalks(A.Cebers,J.Miranda,andM.Widom). Severalaspetsofmagnetodynami
instabilities havebeenillustratedbyexperimental worksonsurfaewavesat aninterfae(R.Perzynski)anddrop
instabilities; 2 posters and 4 artileswere related to the topis. Fromthe pointof view of omplex subsystems,
there werealso presentationson liquidrystals(L. Evangelista), magneto-liposomes(R. Perzynski), and areview
onbiologialappliations(J.C.Bari);5posterswererelatedtothese experimental topis.
In onlusion,this workshop wasagreat suess. It has brought together sientists working on MF from all
around the world. It has given an extended viewon the various ways to approah the study of MF, bothfrom
the experimental andfrom thetheoretialpointofview,analytiallyandalso by meansofnumerialsimulations.
Suh eventsare very important, in partiular for students. They giverise to the establishmentof ontats and
ollaborations. Theyare alsothe plae to onfront various sienti approahesof similar problems, by dierent
teams. Newresultsandanalyseshavebeenpresentedondierentproblems,suh as:
-the spatial strutureof the phaseseparatedMF solutions at the sale of afew m; it appearsto be dierent,
dependingontheolloidalonditions,andleadingeithertoanaggregationortoaliquid-gaslikephaseseparation;
- the internal struture of the nanopartiles at a sale lower than 10 nm; the simplemonodomain strutures
seemtofail forthesmallestnanopartiles,anon-magnetisurfaelayerbeomingobviouslyimportant.
Awealthofnewexperimentshavebeenproposedbythetheoretiians. Inpartiular,theobservationofnew
two-dimensionaldynamialpatternsorofamagnetistohastiresonaneinnanopartiles. Also,biologialappliations
of MF appear as an enormous perspetive for the future, full of rih potentialities. We antiipate impressive
aomplishmentsbyollaborationsamonghemists,physiistsand biologists.
During the 9th International Conferene on Magneti Fluids (held in July 2001, in Bremen, Germany) the
InternationalSteeringCommitteehasproposedthatthenextICMF(ICMF10)willbeheldinBrazil(intheresort
town of Guaruja, S~ao Paulo) in July, 2004, under thejoint responsibility of Antonio M. FigueiredoNeto (USP),
Jer^omeDepeyrot-(UnB,Brasilia,Brazil)
ReginePerzynski -(U.P.M.C.,Paris,Frane)
FranisoA. Tourinho-(UnB,Bras
ilia,Brazil)
