Comparative Process Analysis of Fullerene Production by the Arc and the Radio-Frequency Discharge Methods

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1. INTRODUCTION

S,nce the fist Lepo or lullerene slDrhcsis in 1985, rlcyhale receNed r Lenrendous arrenrlon duc lo thcir unique

troo, 1r.\: l|p .\n re\. cr rull.rcr\ r. n1!(ru\cricquanl'I1cs ir 1990 cnablcd rhc invcstiEaLion ol tullcrcncsin derailr A tulle.ene is a closed cage Inoleculi contain"ing only hexegonal and pentagor^l laces. with a crrtr(nlaLon ar rhe.o,ne,s ol crch hc\rr.n and

't hord rLl(nrg

crcl, cl!c.r r)'picrl lllc.cfc, Cil), has r slrrrenre rn

wliich lhc cliron xlon,s are anarged iL (hc 60 \icni(es rt rtfui.ated icosrhedron, Lypilicd b) a soccer bAll This cor-bor nroLcculc is chonicrlly ard thcnn0l\' sLahlc. IL cdlj bcdisnilvcd in s,llcrr\, can hc pu,iiicd.lunctionalircd. suh-limed. p!\oe.ized I Ore otlle nrosr d(rractilc !turlit0rivonrcchanisns 01 lullcrcnc lomalion, nanlcd as Nnragon.oad rvas pro|oscd by Curl' The lhllcrencs which uro

1am,ed ,n lrricr qurrL,ries Lhar olhci lull(ror(s undor Llr0

spccl{icd condillons couLd i'c dcfifcd rs magic lullcr.ncs {'

MUic lullcruncs dfe: C6L. C?0. CEl'hc lullcrcncs could bc uscd if dille.enr a'cds

hr.Icdc,r|' Jn\.rJIrncr.r. .1hrg) r,r'n '1 lro,Td onconrn)unicalion. cLc l'his nrilcrial and its derivatires havcsLarled lo bc invcsligi(cd duc ro rhetr prunrisiDg preli-

inar} biological activities, $ch as DNA pholoclcavage.Hlv-prrlcasc (lllv-P) nrlrilri(ron, .e!ftrp.orcc(rln andrlutllosis r Tlc llrst tioblcrr to ovcr..mc lor nredjcalu)llrfnliors srcrn! iion, Llrc err.c,ne hldrophoi!ctry .1iullocnos. Undol!drizc(l tu lc,cji.s a,c solublc if riu,',rLrcsolv0nts. buL rnsouhlc ir warci 1-{i bc ncdicall} fs.-l\'1. C(, arrd nrctrlloinUcrL:ncs mu( bc dernrarized Nithhydrcphilic subsLi(ocnts.r h rddition Lo rarcr soluhilizing lullcrures, derilahvc .hemi(ry can hc uscd to prod00c lullcrcrlc'bascd drugs which Larger sFcitr r,ssue

Fullcrcncs rid thclr dcriva(lves are aho attlicd ro .ortnralcrlrls on sonrc che rL.^l scn(!s. su.lr xs quar{7 ..ysL.lr]ricnh lrrcc (QcI4) rnd rircc rcousric wavc sensors

(SAW)' Ir wls ret)oflcd e|f,cr ahoul fossiblc apnlicarl.n'ArLLrr tr, $lon .o..itrrl$uc sLtrtr,ld h| !ld,r$d

Comparative Process Analysis ofFullerene Production by the Arc and the

Badio-Frequency Discharge Methods

Z. Markovidr ', B. T0dor0vl6-l\,4arkovii1 , l. lvloha2, Z. Farkas3. E. K0vatsa.

J. Szepv0lgyi'z, D. otas€viir'7, P Schelers, S. Fe 15, and N. R0rnievi66r"Vinil lnsllluE ol Nudear Sciences, P A Bax522,11A01 Bel1tale Setbla and lvlantenegrc

'1lnsllule 0l ltrlalerials and fnvircnnental Chenisttt/, Che icatResearch CenE[Hungarian Acadeny ot Sclences H-1525 BudrpesL P A qax 17, HungaryjDepannent

of Siticate Chsnistry a1d fula?tkts Engineenng Veszp,en Univercity,H-8240 Veszptln, Egyeten u.2, Hungary

tResearch lnslitule ol Solid State Physics and jptics, Hungaian Acadeny of Sciences,H1525 Bulapest, P 0. Box 49, HLlngary

s Leopold fanzens Universitit lnnsbruck,lnslitut lh lonenphysik.Technikerst.2S, A-6020 tnnsbruck, Austria6 lnstitute ol Physics, P 0 8ox N. | 1001 Eetgade, Seftia and Monlenegro

'School of Mechancal Engineein\, Miika karyca 17, tt000 Eetuade. Serbiaand Montenegro

ln lhis work. compaalive 6nalysis ol processes in cabon arc and radio frequency {B:) ptasmaduring lullerene synthesis has been presented. The kinetrc modet ot tutterene lormation devetopedearlier has been ver'tjed in both iypes o( plasna reactols. The tullerene yietd depended on carbonconcentEtion, velocity ol plasma llame and rolalional lempefalure 01 C, Edi€ts prcdominanty.When mean rolalional lemperalure ol C? radicals was 3000 K, lhe tuttercne yietd was the highestregardless ol lhe lype oi used reaclor. The zone ol lullerene iormalion is targer significanlly in RFolasma /eac]or comDared lo afc reaclor.

Keywords: Fullerenes, Arc Plasma, RF Plasma.

do o I../inD ror r 5 1

Fullcrcnc Prodnclron b! rhc Arc and fie Radro-Frcqucnc) Dschrgc Mclhods

uI

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ultltl(l

ofCrj in photodctcLu and sold ccll.'o Rcctirying hcicro-

iuncrn,ns (dndcs) iabricaLcd from scmiconductilg Fny-mer (MEH PPv) and C, exhibit a large phororesponse as

a rcsulr of pho(oinduccd clcctrun rransfclVarious mcthods halc bccn cxpk'rcd ro pruduoc

tullcrcncs, bul thc mosL a(ractivc is lhe vrporizalion olclrbon in a los'pressure inen gas atnosphcrc whoro dil-lcrcot ,, crl'oJ' J'r u\il ro inJurc !Jrbon vrpunTJron.sreh xs laser vaporizarion elecmcal arc discharse : L - 1

S,,l.u r eryt .r,, Jl'n h u.ed .u\l r1:re .Jr\^n i1 .nr

incrr grs armosphere r '' and obhn qi,Vcfu and higheltullerenes Other processes such as fte cornhustion ot her-zene or hldrocarbons in oxygen-delicient flamcsr gavovcty poo. cfilcicncy as wcll ds pvrclysis ot naph(h.Llcno.:'Oplimlzatiof oi comhu(i(nr mclhod fcrLrltod wilh rystcm(hal car p(rducc iullcrcncs dt rhc lors pcf ycar sllllc wlthyicld (hal ,cachcs :18{,:l

OnLv a few tef'o(s or fullerenc synlhcsis in pl$N0torch rcaclors hrte been publisl'ed up !o now Fulcher)cL al. havc uscd l-phasc AC plasna sct up fof syrthcNisoi iullercncs lnd ccrtain p,oducts oi thc fanrily oi caFbon naroLubcs " h \Ven8 s reporl. radh liequency plasrl!rcrc(n s$ used lbr fte producLion ol lullercnes. ndc.scvcral saseous rondiions ol Ar. COr and He. whicfi scrclbuod to be adequa(c gases Ibr fu ll.renc synlhesis.:" :5 'l hc!r1de rsd l,igh tenperalure lield in rhe RF thcmi plasnrnis adcqL'n{e lor fast cvaporaLion ol cold porvdcr inicllcdinlo il. xnd thcr r rclatifclr_ lot! L.rnpcmurc licld ol.ppmximarely seEral rhousand Kchin in rhc downst.cam

Ernron oi rbc fhena is efttcive tb. a lilh rnte querch-

'ng ol aromic rnd molccula. paniclcs into lullcrcnes.

Con Sanchez reprted rhar tullerenes and clrbon nano-r(bcs (CN'ls) Fe.e synthesiTed in inducrion plasmas r

thc 4GkW platc powerlt Yoshie et al. were used h,vbridplNnr $hich was characrerized by rhe superposirion oiRl rh'mJ Jnd a DC dL rcr 'perJ,eJ dr .,,nu\ph(n\ nr(:sure :? Dubrovskv eI al synrhesized lullcrenes by ,,,tocL,trg

cirbon hlick precun.r into DC plasina ftch.:r Lugowskier al halc syn(hcsrzcd luUcrcncs and rJndohcdml nrcLallo-lullcrcncs by lrng sraidard cxri'.n'dc Lechniquc and d

Noditication nNohing an RF n ucrive couplcd phsn.rdischa.gc " Our prcvious cxpcfinrcnrs ol lullcfcnc synthe-sis in RF [hermal plasma rcacror halc promisjnr rosullson low cost large scale fullerenc production.r0 ri

In lhis paper, a compararile sluiiy ot lirllercnc synlhc-sk rn t\vo difli.enr rlpes of plasna rcdcLor (.l|0 .Lnd Rl:flasnra reaclorl has been repofled

^ krncuc modcl ol

lullc..nc fbnna rn deleloped p.eviousl) was connrnrcd olbdh uscd .c!ctos. Ouicrl emission spe.toscdp) (OF.S)\^as used likc diagnostic tool lb. dctsrion ol spccicsprcscnl durinC cdly phase offullerene sv.Ihesis tsasedonthc op(ical dia3nosrics of generated species in crrbon t|rcand RF plasmn- rorational remperaLurc ol C" rddicals couklhc dctcnnnred Thc oh'rined

'c.ulr\,,I full('cn( p'u(L\$n!

n' RF plasma rcac(q halc shown thal cadotr conccntia-tion deFnded on lhc evap(,ration rarc of grathitc. cncrgy

2

(ranslcr fr0n hot inen gas ro graplile parliclcs and plarmanamc \,clocity signilicardy.I! was lound thll h€at conduc,trv(' connected to lhe stnrctural orderliness of precursorsh s impotunL tulc in the evaporarion ofgraph;Lc pariicles.Thc mosL imponant result E?s rhat (hc fulle.ene lbrnulionronc in RF thedDal plasma rcactor was much larger rhanrn cnrbon arc rca.ror

2. THEORETICAL BACKGROUND OFFULLEFENE SYNTHESIS INCAFBON PLASMAS

Tho fullerenes have been synrhcsizcd in hot inerr gas

.:ct qirh nt1 r.dn dnr .unr ur . - .^n ro, \ Q,. .i .nrdinlensronaljel has bccn ftrmcd by exprnding ofgas ir)mlnlerelecrrode splcc of graphirc arc or expardtrrg ol gas

liom RF plasnn torchIjvaporrlcd carbon al.ms intcracr nruturlly a.d lb,n

chunts. rings and lclcdivc .erbon crges. lhc prccossoi-lluslerinS of carbon rtoms irto small chains snr|s fllcry hitlr (cmpcralu.c. Based on lheoretical prcdictionr,carbon chains arc formed in dre remperalurc range of10000-6000 K crbon rings in rhe.anse of60{10 5000 K,dclcclivc tullc.cnc in the range of 5000 +000 K Aiieranrcaling of deteile cnEcs in rhe rempera$re Tonc of4000-2Oo K, magic fulle.encs uc lo.mcd l Accodingk) M uyrma. tuvou.rblc lcmpLra(urc lbr lull$ene lbma-lim is l{){){) K. Ar tempernture of 6000 K, l.rge clusleNprcalncd ro halc cu,lcd long .hain srrucrurc.i rr Ar lem-peratures low€r than 2000 K clusrers are rransfomcd in(o

Bxsed on Von Hcldcn iNesrigation of carbon .lDsrengeDerded by lascr dcsorprion one can concludc rhar catsbon clusrcrs Cr tlrc chains for r < 10, monocyclic ringslor l0 < I < 50- polycyclic ines ior i > 20 rnd cdgc likcslruc(re for k > 10 r5 } Similar resulrs havc bccn con,firnred by Jarold c( al rr 1 Theorerical calculations indi-cAte thnl crrbon clustcrs fomred 1n themal plasmrs havcsrmplo slllrcu'rcs like chain or ring for C, (tr < 20) and flarsfiuiture\IJ. c /'n.,.. .u..lr..ermep.,rl(lurn rE

f lrr ., rn - nl ( I r., p., '.u,. ,\ ,^^ 1.1, ,r ' .,\.lJrt.r' l.Jf ns ll.'r .r,'hr '". $ L( ,. ri npL,-r 1 ,\ r.nhi8fi, t|e t|ngLcd pol!-cycllc structure rs lavourcd ! Onlywhen adequate lernpcrarurc condition or cooLiDg ftLc rs

apphed, (l'cy can bc rcananged ro hollorv randonr c^gcdslrticlure aid nnally pcrfecL lullerene.

l,lftkc'v,c cl ai has fcpofied earlier on rficorcucalrnodel of fulle.ene i,nnatiotr ln this nhdel. authors havcassuncd {h thc ptucess ot lullcrcnc svnrhcsis dccurcdin lre rcrcror"' Thc proccss of cd)on cluster tonna(toDoccuntd io u inefl heat bath whosc ccomcrry wls drreFmincd by rhe remperarure gradicnr bcrwcen arc arN andchnrnher lvall. Thc raLio ol lalucs of ca.bon Hpour con-ccn(ralion and lelocn} of carhon jcl liom thc incn hearb:tlh (lerermines lhc cllicicnc! of collisions rmong cnrbon

J Nanosci Nanatechnol 7, 1 13 2007

Fulluu,o ltoduortu by (he Arc nnJ r,e Radio-F.cqncrcy D,schxrgc Mcrhods

Iin tho malhemalrcal descrplion ot lhe iirlleretre Iorma-lion. kirrctic modcl hased on Lhe equarlon ol Smoluchovskihut bccn uicd.' Thc laUowing systcrn 01 dillorcnLialcqua-ti0ns is lhc basis of rhe rnodell

,r-|.,.,. iv'Il*,.'i x- -- !j | (.r,,,, {rJ

Th( fir.t sum rrpr.:Lnts rhr rdre ol ,lurer C^ Inrm 'nnlrom smallcr clrncA, Mrh .elatire concentrarion cr, while

lhc sccond sum and lasl rerm fepresent the rate ol dis-appcrrnrg c'l rhc chsrcr Ci in tlc lbnnaLion fo^c(rorrs olbiggor clusrcrs lhe iquare roor pan describes tle rentspcrdurc ArAdienr rn the reactor and deliies boundrq ol'intcemrion. n)r slhpliclry. we harc assmcd rhar rhc Lcnr-

terdlure w s iic{l), dccrcaslng vcfsus radius T'hc uppcr

honndn4' iri rhe firsr sum t,, = (t - l)/2 il I is odd a dk,, = k/2 it k is evei unber. The relaricr is dclincd in lhc iollowine way:

Lr (t=t \t)

$hctc trr rs (hc local coocentration of ihe cluster Ci, rnd,\'. is rhe rotal nririal concentation of cdbon atoms.

DiDrensionlcss variablc X = Ar- thc pram.lcr a = Ats.Dormllircd rc&tion consrdr

Nd, I8teunsrlnr,4: ! _1:tP\

I I rY.

d Ls lhe cross sccrion for rhc collision bctec.n lwo car-hof atonrs. I rs the leloclry of carbon/helium fl id lrom(hc intcNlecnode spacei B: ffi&. In constan( B. 7i, is(hc arc axis temperalr,rrei 7i is ihe wall temperarurc; antlR is the radius of rhe arc phsma reactor

The tullcrcnc yicld is given by thc inlowirg cxprcs-sion: v(X) = k.r. whcre.L is the relarlve concenrrarlon. InIiigure l(x dnd b). rhe dependence of tullerene licld (Ci,,,Cl) vctsus pararneler X has been p,€senred Ir could bcohscrvcd liom liigurc l(a and b) tlm in Lhc casc ol smalllaluer of tlte pramelcr c {g.eal tcmperaturc gradicnls),lhc lbrmrlion reactions ofmolecules Cto and Cr.r could notprocccd (ill cnd i.c.. oDly cctuin pc.cenl ol cdbon !,llpour.sas jnvolvcd in $e lb.mation ol magic tullerenes. Whenrhc parun€Ler C had high values (small remperarure gr.-drcr)t) knlnaln,n rcrclions of Cr- and C--. p.occcdcd com,tletcly and abou( 20.7 ot .dbon vaF,ur us traodonncdilno rrigic tullerenes

llxsed on rhc obtaincd rcsnlts we cotrld conclude rha( rhenron ,mportant qnantir,es shich dererhined rhc fullcrcncyrcld lvcrc N,-conccnl.rlrcn oi carbon rn thc in(crclcc-trode sf{ce, r-lclocit} of cafbon^clu m j cr lror thc inicr-clcclrcdc spAcc. l, rhe arr remperarure and remperdr rcgrudicnr hel$ccn {c Nxls and chanrber walls

J. Nanasci. Nanotechnol 7, 1-13,2007

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10030 5t 60 70 A! 90

Oin€lrrrrl.r:! la.lnlrle X

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Tm

0 1!ril 2100 3000 4000

Oilr!sioniess varable X

lig,,. Yied nigr. fuller.i.s a,r rnd C- rrirtrn.r.f.1(ltvur-rhLe X 'fh. due ot p.nrn.rcr C n 100 yr I ol rnrgic rirld'c(\ CirldC. as i irtrclon of drc lrrlrhL3 \ Tr lalf e ol pi'rrdq C is4500 ltr r|r ltu( cnfLrnccnrdonofgriphirrhcturgcorX r)tr2{)

Thc kinctic modcl descibed above has bclll rcsLco anocofliflncd rn c{rbon arc fearr(tr c\perimcnrally. Whcn (hc

k n(' ! ,n, J(l ,,I f,r h r. re r". -,,. . jrlllL. durng syn-rlrcs'. nl iullerrlc.,1 RI pld.n,r rfJ.ror. quJlrari\c run-nNalion of dcscribed kineric tuodel has bccn obtai ed

3. EXPERIMENTAL FACILITIESAND CONDITIONS

.3.1. Exp$ihcntal of Fullerene Synthcsls in rnPlasna Reactor

'lhc lullcrcnc s)nrhesis hy arc discharg. rcchniq e wospcrfbflned in plasma reactor prcscnred in Figu.e 2.r: l hcvlcuun chanrher in which the plastna has been geneFated was I in lorg and l0 ctn rn di^meer'l|e rrc wasmdrrtrncd bcteeen two graphitc clccrfodcs, whieh w€rerfountc(l on wa(cFc(rcd srainless neel h.klca

F'll-.'. 11. l'r.r.,'l-\ ". \! drd rlc R,d . Fr:qu:r .) -,sc !r \4rir..tr

l, l' I

**",efl- t:-ltlEIg{A PI 35

Fi8. 2. Ex|e nrnLr :e!uf oT trlidrem stfrlrrsis ir !r! plr$rr rrldktr

The graphire anodcs ol 12. 9, 7. 6. 5. ard 4 mn irdirherer werc 99.99.2 purc spcclral oafton (Rorgsdorl).Thc carhodc is Nadc ol spccr.oscopic graphirc. I2 5

'lln ir

dramctcr w(h (hc holc of 6 mm. Thc arc gan herween rhe

elccrrodcs srs l0 mm Ttre power supply used (o generarclhc arc wa.r lhe welding power supply.

Alic. bcing evacuated dosn ro 0.6 Pa by r rolary punp,fie vacuum chamber was isolated lrom lhc puup {trd (hcn

i.ert gas-heliumnvas intrcduccd up to thc dcsirc{ prclisurc.The las pressurc \!ns in rhc rangc l_rum 2. loi to 6 l0r Pa.

The curenr inensiry in fte arc discharg. rcachcd 70 A.Thc blo*ing oflhe grs rhmugh carhode wac reali/ed by

lentilalor The venlilator is locat.d in Lhc small chambcrouLsidc the tuacror The gas flow is measured by flowmc-r(1. plJ({J rbdrf rhc rr il0lor The small (hJnrher i( con-nc.rcd Lo Lllc .eacbr through rle liqrid nnroScn lrap. Thcleotilator is connared lo lhe chambcr wi(h rho U pyrcxlubc rmmcrscd in liquid nirogcn. a\ wcll.

Th. fmr{son..Ilc(rm ol rhc ch(micalsNcics flrscrt inthc ca.bon arc plas'na were recorded hy mean$ of planu

sarins spccrro8raphs of Eben deriSn (RSV). The lishtemined from rhc ca$on arc was proicctcd Lo rhc onlranccsln of specrographs and crlibratcd scrcen.

Thc cmissbn spcclra ol rhe carhon arc in heluor werercsiecred by CCD digital camera (Camedia-Olynrpus C-700 ulLra zoom). The spectra ot Swan nrolecular bands ofc, ftdicals ((0,0) at 516.5 and (0,1) at 563.5 nm) wererco.ded witb tlteoretical specral resolution of 270000 andrecjprocal dkpersion of 0.28 nm/mm which was cnoLrghto rcsolvc thc hnc rolatio.al slucture oi e rissi(rr snectrn.Tlrc spcctrograph cnrrdDcc slit w.rs 15

^rnr.The.hed'ical cotr,plsirion ol lullcrcnc mixturo hrN bocndctcnnincd by Ranran spectroscopy. The tullcrcnc powdcrhls becn dcposircd on silicor substralcs hy rcsistivc hcal-n'S

'n vdcuu'n. Ra'nan spcctra ol lullcritc thin lilnrs wereohuined by Micro Ramarr Chromcx 2000 using 532 nmof a trequency doublcd Nd:YrC lascr. Tho $pccual rcso,lution was I cm '. Micfo-Raman spcclm wcro fccofdcd at

l-2. tlxperimcntal of Fullcrene Synthesis in Rl'Thennrl Pl$na lorch

Sevenl 8raphite lr$'(ldrs (4i127-Asbury Mills, KS4 rndKS6 from Tnncal, aake lrom Alta Aesar, grAdrite lioln

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ulJoFEI

ul([[]|r

Dlg.3, Flrn.imeit sccupott0ltctunr stnrhcJs r Rr;dorr 0E!rd

,{ldrich and 8lass} cufton wc.c subiccred (o lhcrmalc!ap,oruliotr tollowcd by .cconrhiiarn,n in Rlr (hcrmal plarnurcaclor. at aftnosphcric pressLrrc-Figurc L Thc RF powe.was produccd by a generahr opcuins ar f5 MHz.Thc plalc powg ol 2? kW was i,rluc(ivcly cotrpled ro aTEKNA Pl--15 ktrch conncclcd to warerc(x'led plasmarea€tor. cychhc and dust li[e. The exterifrcnlal conda-

lions wcrc givcn in lible l. Both plasma chmbcr dd rheprecursor t€eder *crc clacuaLcd prio. to dre eipcnmcnrsto avoid prcscncc ot N, and O. jn lhc sysrcm. The graphire

Fwder was injected axially Lo rhc rop ofrhe plasma namcwirh tied rares of 5 to l5{) B h-l

Emjssions of plasnras were deteclcd pc.pendicularly roIl'u r\is of pldsmd llJme. rhrough a qudu gla\s w,ndow wirh rhc diamcrcr of l0 cm tippt. rim of windowis placed 5 .n belos lcvcl ol plesmi noTzle The mul-tiple ,iber cntrancc oprics is nrounred so rla( axial scans

of plasma c n bc pcrlb rcd. At this posirion. phcnomcnr occunrng at early slagc ol fullcrcnc tormarion can beobserved. Upwards from this position, heating, acrva(ionirnJ Je(umpo:ruLir ^t tr.ph,re pdl(r(lc. dc hrplFnrnCwhilc downwnrds. combinadon of aclivc spccics to morecomplcx str'ucturrs is takrne placc. Shape of plasma flanrewJr r((urJ.J h) N.ko d.FIrl (Jn,Jrr rhrulsi. qurfl/ \,n.dow on the chamber

Thc wrvclcng$ rvas selecred by r 55 cnr focallcnglh monochromrror (medium resolution monochromator. lRIAX 550 lobjn-Yvor). Holosrrphic sfarinss withl2/\r rn.l lJl00 rr,nre. I r, l, trJ brlr -:, o l. rc ,f.rocal disp€rsions wcrc | 55 and I nm/mm. rcspelrively.Ligli( was collccred afd rrdislen'cd (o lhc cnrnn.c slirr4 !r'l l-. .. ,,,u ' -,r 'JrJ hl.r h,rnJlc Inc p ,.',r, , ,,.

v.u (!l i,r rhr r..rdJ .'r I r. :u s lh.n I .r.',..,,n ^r.dcrcctcd by af oprical m lti-channcl analyzer (CCL]000.1024 x 256 nixcls) Spcctra wcrc rccoded und p,occsscdby IC. lbr cAch st)alidl posiliof. l0 scrns nrc avenged rorcducc thc ifllucncc of siSnal flucruarions

I

J. Nanasci. Nanatechnal 7, 1-13,2007

Fullercnc P( uctron bt Lhe Arc and (he Radi(lFrcquency Dischargc Mcrhods

Tabl. r. liprcxl gai comlixnnN in rfu RI plarDr rcrcror

l ,, sLnn) (1lr :lpi,l (A: sh d) {rrc. dpdl

rl32

Thc mcan panicle sizc of prccursor *"s measured byIa\or diffraction tahniquc usine Mdvcm Masr.r PaniclcSiTer M6 l(l llorphobgy ol r(xn w$ chrracrcrizcdby scAnnins clcclron micfoslopy (SEM. Philips XLl0ESBM). Phase conposidon w$ determlied by X-rtLydifiiaction (XRD. Philips PWl7l0 difiracromerer. CuK.radranon And sraphire monochronurof (45 kV l5 mA arddivcfgcncc l") Thc mcan cfyslallilc sizc (Lsr) was dcrcr-mincd from rhc l-i'uncr (%igh mcrhod) analysis ofsinlleXRD'lanc profilc. Diamclcr Disrrjburion Anallzer Sot'l-*dr( w$ J(fLl'lPfJ In urJ tu d(tljrmrn( rh( dpuririonratc ol prccursor durin8 procossinr of prccu6orrr

Main imp(ri(ics of lhc prccurrc'rs wcrc derermineLlby ICP-AES (Thermo Jarcl Ash Aronscan 25). Inor-Srrrc lon(cnr of the grrphirc powders were dissolvedhy cc HNO,AIF frixture usirrg a microwale dieesrior

l:ullcrcnc contcnl of Lhc ci(r{c(s wns determined bymass spc(rroscop) (I\tS) and hilh performance liquidehrornarography (HPLC). The MS nEasuremenrs werepcrlormcd by n hish resolurion, donbte focusing mass

spccromcter (Varian MAT CHs-DF) of relersed Nier-Johnson typc BEI gcomctry lombincd with a second elec-lrorLau! nnillzcr E2. Thc ruix(urc ol tullerenes whrchconsisrod ol mainly cdr. cl, ca, c , Ltnd clr was cv(p-'rrc.l rn ,. \ h.,u,, , r

'0,{,r 't ' Pr. rr br i \, n .,nriJ'r1jr the tcrrrnemrure range of 55(l to 800 'C. In these condit'ons both ncgalivc and posnivc tuns could bc fo.mcd.

_lb

prod$.c posnivc ions, rhc cffusivc beam was nr(ersectedbI rn cbcrron beam having e ergy of l0O cv dd cudcnlof 370 ttA Tle resulti.g ions arc exkrc(cd pcrpLrdicu-larly lo the lullerere and electron bcams and accelcralcd torhe analyzing part of rhe mass specfin'neter by a potenrial

Soxl!x cxlraclion merhod was uscd l! scpa.aLf lu tercncstion soor. Toluene sl:'lurions wcrc cvaporated,n dre ro{arycvafxrrator. Mass of d.ied lullcrcnes was comtded tolhc muss o[ soor in ordcr (, dctcrminc rhc fullcrcncyield. In ceruin cases. fLrll€renc )i€ld was decrnrined by

4. BESULTS AND DISCUSSION

4,1. Synthesis of FUlerene in Arc I'lasna

ln rhis section, curen( status of tullercne syrrheris byHrious nNdificaaon of carhon arc mcrhod has Dccn

J. Nanosci. Nanotechnol. 7, 1-13, 2007

LLI. Chenical Co'nposititt t'f Atc Pl!'s'r'.

Oprcal emassion spect.n ;r rhc spcclral rangc oi 4(XF700 nm $ere record.d during arc discharSe In inen gashclium. tsosidcs Swan molocular specrra with bandnc{{sal 516 5 nnr l^r - 0), 173.7 rm (,\ii: l) ird 563.5 ririr(Ar = l) Ihc emi\sicDr i(nn C I (658.76 nm), C 11(657.8and 6s8.288 run), Hc I(j87 6 nm), Hc I (667 8 om) havebcen obsch-cd as wcll. Thc prcdominanr ti:nrure in lh€scspcct.a tlas fte swa( hnfld cnrission sysrem rha( resulGlio,n tl'e tnns,tion /'l1r +trrll,, { 15

A typical cmission spcolrun ol Cr radicals wirh band-hcad at 5615 nnr has heen presentcd in Iigufc 4. t'hcdashed lines represcrr erpcriinenral dard dnd rhc sdjdLines xre calculated spcclr Molcculu spcctra of C.

''adicals obtained cxpcrimcntally hivc becn liued ro rhe

lpccxa oblained by calcul.rtion.'6 As car be seen rromFrgu.e l. rhere i. d go,rJ ag(..(mcnt bcr$u.n c\t^*.im(n-Ial and theoredcal spccrrd of C, radicals. Thc e i'cr ofscl|'ab!)rplion could nol hc dcrccred in rhis wavelengrh

Tlc .ota(ional rcnipcruture (4!) oI c. radicrlx havebccn dc(ermincd hy ht(ing the experime.ml and srmuraLodsFcfiaL? Sonre aurhoN have de(ermincd rorrLionaL rcnr-peralure ol Cr b) rccording nrclecular emlssion specrru of(0-11) bard wirh bandhcad ar 516.5 nm (19361 08 c r ).a{In uur (drliLr (rprnnr(nri. lhc ctlccr nr rh.Jhy,Tft,rr

nra&IttoI!j

1-m

E

wav6iui'b3,icn ) I ro'

Fi3.4, Fnrii! of cikuLdrd aid crpennenral .Nsio. ntci" ofC, ftdjcrls k/rt\ id'rl. Sqln b!trd (0.1)j c.rflkd in c!|hon lrcDliinr ar 36 pt ssu.. ol 2 10' Pr rnd cuft iircirry of ?0 A?: - rt00 x.

Fullc(ne Prudu(rDn b) rhr Ari d thr RddicFcqucnq Dsch Ec Mdhods

in this wavelength region was too strong'6 sincc rn theelecrronic transitions the lowrr lcvcl was (hc gruund onc.In rhis way, th€ calculared lalues of.otalional rcmpcraturccould nol bo rcliablc.

1.1.2. Eueck oJ Cafion ConcentmtioD onFulerne Yield

The lirllerene produclion cmcicncy dcpcnds on fte rypeoI uscd inen gas signincanlly. Thc usc of hcavicf ineigas tlan heliom causcs rh€ d€crcaso ol lullcrcnc yicld.r'The rate of evaporatjon dcTcnds on thc ratio of ionazationpolenlials ofincrl gd\ and carbon- Compared to other inengascs, only ioniarion porential of helium is highcr sig-nificanrly rhan carbon ionization potential.l'r The heliumionizalion potcntirl is 24.51i74 eV while the ioniTarionpotenlial of carbon is I 1.2603 cV In hclium cnvimnmcnt,ion cune t in carbor arc is composcd of carbon ionri.slThe.efore, lhc rarc of cvapomlion ol graphie electrode isthe hiShest in the ahosphcrc of inod ga.s hclium. Oher.Mhors have lbund rhat anode erosion rarc was rwo riml:shigher in heliunr cohparcd lo argon and ron rimcs hiShcrcomparcd (o ncon.Lo ln thc athospherc of othcr incn g csthan helium, ions ol incrt gas transftr the culrcnt ulongarc channel. Hcrcc rhc rarc ot clccrmde €vaporaion is a

B€sides rhc raLio of ionization porentialofin€d gas andcarbon, the rate of cvaporarion has dcpcndcd on rh€ pres-surc ol inen gas. The iacrearc of thc prcssurc ol incn gashns aIlccted fie decre sc of clcclron transfcr to anodc.r(''lhc mai pat of the elcc(ron cnergy h$ bccn Lrmslcrrcdto carbon/h€lium plasma namc.

4.t.i. Efrects oI Gas ueloc r on Fu er.ne neu

tsascd on thc rcruhs oforher aurhoN. it w{s aound (har rhcvelociry ol carbor/hclium plarm! tlanrc on axis is ltx'ur200 m/s and decrcascd with thc incrcasc ol(hc mdialcooFdinarc from axis in invers€ law tashi,)n-qrl When Lhc dis-tance berween eicdrodcs was largc. rhc cxprcrsion tbr ietvelo.ity on arc is was givcn by th€ followinS:5'

4.1.4. F,fecB o! Rotaaional Tenpentur. ol C. Radicalson Fulerene rieA

In thir work, we havc obscrvcd the variarion of rotarionaltemnerirlurt: of C) rudicals lersus (arh,n concentrarionduring lhc p.occss of tullcrcnc lbnnarion. Thc varying ofoarbon concentration has bccn achieved by using graphiteelectnrdes ol dillcrcnt diameers undcr Lhc same cond;lion (prL = 2 10{ Pa, /=70 A). The carbon concenrra-rion or rale of anodc crosion was decreascd wirh €lectrodediamclcr (d) incrcasing. Thc incrcas€ of elcclrodc diame,ter affcclod lhc increase of hcar conduclivity ol clclrrode.h this way. hcal was lm sl€ned f$rcr iom anode lip rocold end ol this clccr.od€. Funhemorc, rhc cxperimenklrcsuils hayc shown rlar tullercnc yicld decreased wilh lhcincreas! ol clecLrudc diamctct.'!

Thc dccrcasc of t€mperaturc wdr! thc slowesr in hcliumcnvironmenr- The reason for thar was higher hcat conduc,tivity of helium comparcd to orher inen gasqs. Bas€d onlhese conclusions wc could assum! lhat lhc rcsrdence limeol carh,n clusrcrs in tcnpcrd(urc rcgtun 400F2000 K was(hc longcsl in helium.

Whcn the carbon conccmrarion was low (d = 12 mm).thc v.rlucs of mcnn rorarionirl lcmpcraturc were 7000:2(Xl K. Und€r thcs! conditions, tullcrcnc yicld waslower than 2%. l-hc carbon vapour (C, Cz. C,) wasmainly locarcd bctwcen gmtthile clccrrodcs in molar rariol/2.8/4.5.56 Thc lincs ofC n, He / and C? molecular bandscan only be dctcc(cd in that casc. The collisions amongC: radicals and electrons wcrc rhc dominanr mecnanrsmof ercitation of C: radicals. In re opposirc ca.so, when rh€

carbon conccntraljon is hi8h (,/ = 4 mm), lhc values ofmcan rohrional t€mpcrarurc ol C: radicals wcre 2500+200 K. As a rcsulr. tullercne proccssing w$ hiEhly effi-cicnr (yield was I 3. I %). Thc carbon vapour was lolalcd ina wide region: betscln and around rlte electrudc.i. FiunheFmorc. carbon atoms-far fmm arc axis-fonn C1 moleculcswhich could no( b€ €xcired by rhc collisions wirh elec-lrons. Chcnriluminescen! cxciration ol C, radicals was thcdominan( mc(hnism of€xcitarion ol C, radicals. In olherwords. thc cxcitaton of tfies€ molcculq\ is rh€ resul( ofchemical reacrions.arher rhan of inelairic non{cactiv€ col-lisions. Bc.sides molecular bands of C, radical, only linq\ol C I could bc dorccred in thc sp&tra when crrbon llrn-

Sincc the selt-absorprion has beln rcvealcd in motc.u-lar band with bandhcad at 516.5 nm. onc could concrudelhat a lo( of C: mdicals wcrc in ground stare (0-0) tu.away ot pla.rma. Mos( of C, radicals have not pa ci-pa(cd rn tuller€rc fu.malion undcr rhe optitnum conditionlor lullcrcne rynrhe\i\ (qhen fullcrcnc yreld har a nu!-ru'n valuc). Thc rnain rca.\ons for thot wcrc lhc follow-

inr: veloc(y of carbon-helium pl.$ma jc( was roo larg€ orpl$ma temFmrurc wus (oo high---{hdn and nng ca.bonclustc6 did not litrm.lo

(1)

where l-currenl inrcnsiry, S-crcss scctiol. p-gas densityand /r,,-magnetir pcrmcabiliry of vacuum. Exp€rimenlalin!€sigarions have shosn lhat (hc incrcase of cuFenlintcnsi(y caused the decrease of fullcrcnc yicld.si Th€rcsidcncc rime of carbon clustcrs was csrimalcd on0.2 ms undcr conditions which thvourcd fullercne foFmation (velociry was I0O m/s. lcngth ol plasma jc( wa.s

0.02 m) and could bc dcrcascd with increasing ofcun€ntintcnsity. In the carbon arc rcacbr modincd by graphircuhe which was po:iirioncd pcrpcndicular to lhc clcctrodc.s.incrcasc of helium flow rare crused rwofold dc{rcasc ol

1;y 4tsp

J. Nanosci. Nanolechnol. 7, 1-13. 2OO7

Fullcrchc Pmdudl.n hy fte Afc ord Lhc Rddio Frequen.y Dis.l gc Metlods

IE

€lIi$

:

""1---.--_-.-.---.----'----'----20' 3]0 irrs an, 3s 7!0 30c

$€vereiglr (.ml

IjA,6, \',sibl. rlr rviolcr il$i,p(0. sF..0r ot nnuoir $trxd itlulld.re soor (do(eLl li"dl i'd

'rreref.. ci (rulllirc)

Raman spectrum ol lullerie nlns dcllosi{cd on siliconsubsrare is rrdsented in FiEure 7 For C.,, and C?i lilms.Raman lines .elaed lo lhc isolated vibrarional modcs ofhnth Inolcculcs. dre cdrily uhs(ncd. Thr morc rnl(n\ccharactcri c Ramun liros arc locatcd ar 271 (IIg). ,{93.

and 1469 cm I (Ag) for Cd and ar 260, 1062. I 185, 1232,ind l56E cm (prolubly D5 h modcs) lbr C,,'1 5r

4.2. Syntb€sis of Full€rcne in RF Plsnla

This secrion is devoted to the resedch offult€rene svnnesis in RF fiermal plasna reactor

4.2,1. Chenieal Corytosition of RF Ptas'na

Oplrcnl c'n'ssnxr spco|la if thc spcctrrl ri gc of 300 to700 nm wcrc rccordcd bclorc and during injection oflraphire po$de nto thc tlasma.

Th€ edission spectrunr ofrhe pure Af planna consistcdol mainl) Ar I lines with only sone Ar II emissions ofIow nrrensilis. [lccrron tcmpcrarurc calculaLcd by thc lin€to cont'nuum mcrhod war lo(rd lo bc 10000 K.:,

l

1000

Raoa. s.li 16 1 t

ooo o05 0 15 0 ?0 0.2s

€R'torrzrF? {9 h?k12lm^ 121

Fis.s. Fullocrcyeldas. nfdiN0f Aft Lli_/r'r vrlue ER {mdsrir u!\ior rrrt T[! .uif.f r was ?0 A. hd i!f1 f t*trra,' : 6 l0r Pu.

4.1.s. The Synetgljtic Elfect oI Cathon Concentation,uelociO ald Tenperalwe on F lercne fieA

The dependence of fulle.ene yicld vcrsus lariable whichjs proponn'nal to X is presented in Figrrc 5. The vari-able mertioned abole rcprescnts (hc ft io ofthe producr ofanodc crosron rrle and squared mor ol plasma LemperirLrre

rDd squl|rud pllisnrjc( lelociry. This dcpc dcncc obranr€dexperinlentally is almosL idcnLical to the theoretical depen,dcncc oitr'llcrcne yieldversus !ari.$lc X (Fis. l(a and b)).The highcst transtormation of carbon vapou into fullereneqd\ obriinlJ for clc.rrodes ol 5 and 4 mm. Tfii\ m(dnstlat by tle turther decrcasing of cloctodc dirmeter, thctullerenc yiold is nol ircrcascd. Thc mAximtrm valuc olluuc.cnc yiokl was l: l!'..

Our oxpcrimontal resulrs have shown thrt the fullerencyield was Lhc higficsr when rhe product of carbon lapour.oncenlation and thc squarcd root of rotationrl tcmpcra,rure of C, mdicak was tfie highcst- Conrpamlile dalysisol erpcrirrcntal and thcorcLical rosuhs pn vides a beuerundersranding of the fullerenc fonnalion mcchanism. The!:rlidit) of kirelic nodel of irllcrerc irmarion has beerr

.onli.med durirlg synthcsis of i\rllcrcnes 1n carbon arc

4.1.6. Ch$a.teh?ltion of FuUereneN Slnthesized i,t

In order ro chamcterizc fulicrcnes, UV-VIS sp€cr.opho-tometrv and RrmM speerroscopy trrve been pL'rlbmod.The absorption spcctrnm of tollLcne extract oi tull.rono$ot a d tctcrcLlt C6r Ic prcscn(cd ii FiSurc 6. As iorrelefoncc Cd, spccnncn, boad peaks !t 216,264, andll9 nm dominarc rhe specra.r Weakcr srrucrurcs showup h {'e visible. including plrtcau belween -460 rnd500 nm. Compdrql t,, r.terence Cn. spccrm.n. ahv,rntnnspcctrum of full$ene mix$rc (C6/C?,) was ahnosl idcn-tical. Poaks at 264 nm and 339 nm wcrc slightly shiliOddu€ to tho prcscncc of C.L, in tullercnc mixrure

J Nanasci Nanatechnal 7, 1 13,2OOz

a]|t(ttmDo

!'{61-m

€

Fig,7.

l

:

Ri,na. s0.crrum ol l0ll.nr $in iil'cs dDposit.d on sir'con

Fullerenr Prcdu. rion bv lhc A'( a'd 'hc

Radro.Frcqucncy DD(huBc Mclh{di

; s000

.g

; 6000

,r}] t::o ,.1 460 430 500 520 54c

Mv.,eryrh l^n)

Fig.3. Sp.ctum olci.bor laF plasnr

ln the emission specra recorded during nlection ofgraphite porder C, rrdicrls wcfc obscrvcdr thrcc vibra-nonal sequenccs with bands at 516.5 nm (,\u = 0),473.7 nm (A!: +r) and 438.2 nm (tu=+2) cor€lpond-ins ro {hc swan handr of C, (Fig. 8)- Aromic lincs oi CaII were dcLcctcd aL wavelengrhs: 393.37 atrd 396.85 nm.Thc prscncc of Ca II lires in rhe r€corded spe€rra couldbe cxplaincd by the impurity of used graphite prccursors.Bas€d on XRD analysis it was found lhat thc tnain impu-riries of KS:l po*dcr wcrc I-t (lrl5 ppm). Si (50 ppm) andCa (50 ppm). Molccular bdds of CN radicals wcre no(derecred in rhc spcrra duc ro careful evacuarion of rhe

system beforc thc cxperimenl,sRorarional remperarurc (4,,) of C, radicals was de(eF

mincd by fining .he simular€d and experimcntal spccrra(drl3 -arll,, ^ir

: 0).{ m Fisurc 9 shows u ryprcalemission spectrun of Cr radicals during focding ofKsa powder ((0-0) molec'ild band wnh bandhoad al516.5 nn). Thc dashcd lines rcprcscnt cxpcrimcntal dat ,$hil€ solid lincs srdd for l}lc simulaLcd oncs. Sincc llcrcis a good ndDg of cxpcrimcnLal and {,alculatcd spl"c-

lra, onc can conclude rhat seltrabsomlion elfeci was not

Fig, I0, SFIM nricNsrdpl ol Ks4 (scd as precuisor during ruller.rcsy0dtcsis in RF {hermrl plasnra Edo.

prcs€nlcd in tlrc ohserved molccular band!? Lack of C,radicals in cold regions ofreactu is aconsequence ofcomplcle in(eractio. of C, radjcals rnro larger clus{crs. Longerreside ce dnrc of caLrbon clusrers in RF plasma comparedto arc plasma prolidcs necess^ry condirion tbr complete

1.2.2. Efliects of Cafion Conce latirn oFullercne YieA

SEM microgrnph of graphilc powdcr(KS4) used a! precur-sor during fullerene synlhcsis in RIr the.mal plasma rcacLo.is prcs€nred in Figurc 10. Lass diffrdcrion aalysis has

becn rclc.rlcd rhaL panicle size of KS4 is yeied in fte rangeof ll-6.41 pm. Mean paniclc of KS4 graphitc was 3.7 pm.

Tho rypical ofiat of fecd rale of uscd p.eDrson onfullcrono yiold (rhe iull€rene conrenr of sooo for dirlcronL gas composition is presented in Figurc ll. Ir is

observed that in$ease of thc hcliun conccnraton frcm30dlr lo 60./d resulted in 50% increasc of ftrllcrcnc )ieldIl rerlrs ln ll,e impo(dnc( ot hc. rrrn:rHr thennmena ,n

6.0

uJJoFc

arx' .luout(E

36

!

8I ro

,rtl :0 !0 r, 50 d 70 8a 90 r00 ..0 ,-Feed lalo (gih)

rlg,ll, F_ullc@e yicld as r funcrion of fed an. of KS,1 piphnr po'Fig.9- Fin;n! ofcalal.r.trl aid.rpcrnn.nnlsp..ti olC, r.dicals ol dd !t difti@\ gas ornposnions (hcliufr .uncmFr on ol 10.3 dd 60?((H))b 'rd5l6.tnm.l.cdrarcofKs.r{$1501i,.4,=5500K. xrc reprcssncd bt ltll md dnslullincs. rsp..rivclr-l

J. Nan6ci. Nanolednol 7, I 13 2007

Fullercnc Production by $c Arc md rhe RadiGFequency Dii.harye Mcrhods

tullsene titrmation in panicular condidons The tullereneyicld dcr€ased wilh the incre.ae of tird late due ro cool-

SEM oicmgraphs of fullerene soor collecled fromwatcFcoolcd coppcf fod inscncd alonS reactor axls are

rrescnlcd in Figurc l2(u, b, c, d). As can be sccn itornFisurc l2(a), therc was A lot of non,evaporared graphilcparhclcs. lho bost cvapolr(ion ol p.occssed prccu.sor was5f5? cm bclow the nozzle of plasma torch-Fi8ure 12(d)

By rnalyzing of SEM micrographs of rhe tuller€nes@1,1' thc evaporalion fate of KS4 graphire precursor wascalculated The evapomtion rate presenrs volume fracrionol padiclqs smaller than I Fm We hale assumed $ar allsphencally shap€d panicles with dianerers snaller thdnI Am have been creat€d by coales€ence of carbon clustersed fullerenes. Significanr anmunr of small panicles wasdepsitcd on largc non-cvaporatcd paflicls. Thc cvapo-rat€d padcles hdve spherical shape, while non-evaporarcdparticles have disk-like shape. similarly ro the precursorpa.ticles. Based on SEM micrographs we could concludedra! dre evaporarion ratc depcnded on rhe pafi ofrod whcrclhe soot had been collcclcd. Thc eraporarioD ralc wa, inthe rarge of 4-6.3 volto. The lo$,est evaporarion rarc was21 25 cm below thc nozzle of plasma m.ch (Fjs. l2(a)).The highesl evaporation rate of used eaphite was 53-57 cn from rhc nozrlc of pl6ma torch (Fis. lz(d)).Incomplerely €vaF)rc(i(m of ptucessed graphiie powderailcds st.ongly thc carbon conccnt.arion

Il was lound carlicf lhat llll€rcne yicld depcndcd oncdbon .on.entmLit)n. Evapombn mte. energy rranslcrliom hor plasma g.rs lr) graphiLe paniclcs and tho tcbciryoi plasma flame alle€t lhe cirbon concentratioD signifi-canLly. Evapomtion rate of processed graphite p^.ticlcs hasbcen dflectcd by cncrgy rraDslcr from hot plasma gasos tographile particles. Thc energy rransttr froh inerr gas ro

eraphile particl€s was better wh€n plasma gas was heliun-Iigu.e ll. The helium has heat conducrlviry lvhich is 4Lo 6 LiDcs largcr (han argon.ro Upon inj€Lion of hclium,the volune of RF pla.sma dccr€ases.6r In this way- fte dcr-sny of excitcd aryon aroms. ions and electrons increases,and rhe plasma remp€mturc gels higher Hence lhe remper-arurc of surrounding graphite particles becomes high€r ftarensures more favourable conditions tbr tullercne tbrmarion.

The rale of evapomlion of graphiie panicles iniect€d inhot plasma flame is allbcted by heat conductivity. Hearcondtrcllvity of graphite pafticles can not be measurcd ina dircc( wdy. Iror lhis roason, wc donncd the ratio of mcanparticle size and crystnllite size (Di!/r!u:), as i parnmc-tei characrerizitrg hedl conductility of precunor ft is rea-soncd by tlc iac( lha( p$licul rario is proportioD. lo lhcnumber of crystalline boundaries, and thus ro the rhcrmalconduclivi(y ol graphik powdcr. 'Ihe lo$cr thc rrtio, thchighcr is (hcnnal cond$ctivity ('l.able II)

In Figure 13- tnllerene yield as a tuncrion of D5illrr isprcsenled. As can be observen lrom Figurc 13, thc highcsltulleftne yield was oblaincd in prc6sins ofKS4 powdcr

J. Nanosi. Nanotechnol. 7, 1-13, 2OO7

fiR,12. SEM dimg.rphs ol fullcrcnc sxr rollccrd from *abcNlcd rotl inffen inb rhe RF pldma Mckr: (r) 2l-25 cn (6) l!37 .m. (r) 45-"19 cm (d) 5|5? @, n F lhe no/zls or ph\ma kmh

(a)

!mam

o

-lo-ttr

Fullercnc Productior by (h. A.c ard thc Radio-Fr€que..y DKcharye Verlbds

T.bl. ll, l.Idrploldgical proltni.s ol lnphire Fx{.R usal

l28,0q..g 30g9 2.5

lrJ

9F|r

tuttttuIE

\r'hich had rhe lowesl Dr,/I,,,,. ratio. KS:l graphie wasTound to be rhe best staning mate al.

1.2.3. Ellttts of Gds uetucitr on Fn erene Yka

Bosidos par&nrcr.rs ncnLtuncd lrbovo! carbon conccnm-tlon dcpends on velocil! of tlasma nrme ir Fhich clrbonatoms and clurrc6 halc bccn gcncrulcd. Typical condirionsprcrailinC in lhe dischargc and irt the erir ofthe torch no?-zlc drc romp!.rnlurs of thc ordcr of 8000-10000 K and

sas vulocirics in rhc rnnsc ol 40-50 n/s (plare power olplasma torch was up to 200 kW)6r Bascd of our calcura-tion, tho mern velociLv oi plasmr namc hrs esdmared rohe ' dre Innee of 12 20,nh irr thc rcgion l0 cnr bclowthe rozzlc'Lr Otrr estimale oi rcsidcncc rimc of carbonclusters in RF thennal plasma llame was l0 ms (lclocllylvas Z0 nvr. lengrh ol plasnl.l llamc was 0.2 m). Whcnfullcrcrrc was processi.S io DC plasma torch wirh lcloc,itics ol plnsma flame ncrly 1000 m/s. yicld of fullcrcncswns lowcr rhan 2%.23 Yoshie et al. slbwdd $ar rullereneyield decreased lersus lhe increase of velociry of plasmarlAnre r? They lrduced the incrc sc of lclocir) ol p,a$rrflarn€ by decrease of the pressurc in thc rcac(of

4.2.4. EJlects ol RotLtionul Tenperutw. of C2 Radicallon Fu[ercne YieA

Figurc 14 shows the eiLd of roralional tcmpcralurc ofCr ladicak on tulleren€ yield. Rolational tcmpcraturcs of

4000 4500 ar0, a$0Rolullonrt leel.,al!.e1K)

Fig, l.l. Thc n' udn( .l (rlrdtrrl rcm|EraMe oi C, r{dL(!a or

C, for KS4 powder wer€ in rhe range of 3500 5500 K.Similar rcsults havc obtaincd fo. orhe. used precursors.,,Results plc'cnk,l in Frgur( l. indrca,e,hJr rl.e rncrc e

c'Iro(ational tempcrature of C. radicals caused decrensc oftullcrcnc )icld At snr.ilLof loads, C, radicals have rirre rothcrlrlaLizc \!irh

'nc( onvirutrmcnr. At larBer loads, rhcfntAl

gmdrcnr bcr$een hot irrcrL g.ts nd cold gfaph(e parliole isexrremely larle. In ordcr lo claporarc la.gc bad, plas alends ro deliler largcr parr ol cncrgy ro graphirc ic.. higherllur of inen arcms is dirccred roward graphnc.6l Hcncccollisions *ith C. radicals occrr. lhat resuh in higher rora-tional cnergy of C, radic ls.

Obtaircd r.sult was in a good agrdemenr wirhMrrruyama thcorelicr pro(licLions l Lowcr valucs of rrrta-liorial lcmpe.atures of C. radjclls 0rcarl) 1000 K) w.ts aniLrdicalor of good claporuti(n of graphirc. hrgh conccnLra-l'on ol carbon vapour and low reloclrl ot plasma lianreCombina(ion of these hctois tacilirares rhe effciency of

4,2.5. Charaden&tion of Fulqenes SrnLesi.zed h RFThernal Plasna R.actut

1rr iullcrcnc mixturcs rcpur lud lroDr (hc soor by tc'lLrcnccxlracion. lhe individlal fullerenes were trlentilicd bymass specroscopy (VS) and high peribrnance liquidchrom^tography (HPI-C). In order ro derernrioe rhe com-position of fullerene sample more precisely- a massspccrruln of n%arire ions was mken In tliese eledronauachmcnts no fa8morlarion occur.s Fi8ure 15 showsIhI iull(rLn. mr\,ure FnJ-.(J lr.,m |\S4:,:phrr( J.4r-trirs the folLowing main coinponcnts: C,,, Cr,. C"i, Cr,,

The HPI-C chromarogrA,n of toluene extracrs fro KS4soor ls presented in FiSurc 16. Two maior pcakr (q0 ndC1,) lver€ detecled in a wciSht ratio of lll:7 at rctcn(onlimes of 7-? and 12.9 min-.cspcctiycly OxvScn dcdv csoi C., add Cr. such as Cd O. CdJO,. ad Cn,O arc also

_6

l0o ,at 500 500 700 300 30t

Dro/Loo2

ti& ll. Ftrller.tr3 yield a\ r iuncinr ol D,l?",, tor dinimr smphirrp'Rtrritrr llelinn d.:r.n' *r\ :r0?

10 J. Nanosci Nanotechnot. 7, 1-13.2007

Fullerunc lrroduclur by the Arc and rhe Radio,Fr.quetr(y Disch Ae \.{ethods

i

4.J. Complrison of Arc ard Rf Plrsmas lrudnsFullcnnc Pmccssing

Although the sytrthesjs of fullcrcncs in arc rcacror is ft€mon populdr $ay,,t rhc tr4du(rron oi nracros(opri qumritios ot fulle.enes. the perspccdlc of laree scale low cosrtullerene synlhesis in RF plasma feActor is quite good.Tbc mdn disadvantase of tullerene synrhesis in arc rcac((n is Lhc sharp decrease of fullorc|lo yiclds ar dLschargecunefts lbove 100 A. Il rs duo kr high \]ctocrry oi (hc

nlasma gases and hencc vcry sho{ lcsidc|ce time ofcarboncc'nuinnig specics in rhc bot plasma region. Tn RF plasmarcac(o6 morc soltrminous plasma llames are fbrmeo uogas vclociLios arc much lower rhan in arc plasmas.In Lhisway, the meao residence rime ol rcacLivc spccies ir the horplajmaregion is longcr in RF Lhermalplasmas compared toarc plnsmas Lo* cosr powder-ljke sl ning mrlcrial can bcint!od ced rnro RF plasmas $ith etsc, lonLiary ro ar. plas-nlns lJr addition. lted .atc ofpowdcrs crn bc independenrlytlrrnted of RF plasma par.rmclcrs. lho only disadvanrageofRF plasma p.ocessing of iullcroncs is doposnion ofcerbon vapor lbmed by complete evaporntiof of small pani-clcs on incomplclc cvapoftlcd bigger parlicles As i resDlrcoDccnlralion of carbon vapor js dccrcuscd.

l, rh( rrub, n d. rfJ. rL-. rh( ^'r(

,,i tullcrrr,r tormr. rn$as about 2 cm long. The tbrm iorr of full€rene shns arradial coordinatc. 12 mm tron arc axis and stops at l5 mmAr larscr radii (r > 35 mm) rhe qrn riry of fulleren€sdcposited on fte collecror remnios praerically consrmL..t

As tbr synthesis of fuUer€ncs in ltF thcmal plasmarcactor, the fullerenc licld dcpcnds on thc pr( ol rhc rodwhen lnllerene k)(n has beer collccled I his dcpcndcnce ispresenred rn Flgure l7 Thc watcFcooled coppcr rod wasinserted along tl'e reacror rxis and lhe lull$cne soo( $ascollected tionr se.rlons wirh le'rgrh 4 crr. Thc fulle.eneyreld uas nreasured for each secrion. Thc lowcst fullcrcncyicld $us found lor rhe sccrion 2l*25 cm from (hc noz-,lo oi pl mr rorch (0%). Thc highosr lullcrcnc yicld has

700 tso 000 850 t@ ,5! .10t0 1050

mass Per cha,ge {-atp'r]sl

Fi& t5. Hiss sp.ctrDi, .l ncA ilcl! chrre.d ruucEn* iomEd viirrcc.lcfron rtrrhn'fnr h !n cffusnc bc r of ncDral fnll.rcnDs of rhczftr.' trom iKsrl Tl'e crc.tron cnctr ws ckx. h 0 rv md r|E vrportdioi tnp.((,. ol*rs 861 K

prcscnt in rhc nrixt$rc in srnali rmounts (pcaks 2, l. and 5,rcspccr'vclyl. Thcrc c scvcral pcaks at highcf fctctruorrimcs (6.7, 9, l0) (hal cun bc assisncd (o highcr lullcfcncs(Cri, C.N. C$, and Cid). Pe.ik 8 prcsumably concsPonds roCs! or C!. ln rhc lack ol-calibralior. quanrita(ivc !ndlysisof higher fulldrenes crnnot be pertbrmed.

Uu. tu unn lrhl( J{r( ninJriun uf{rr(.nr uf(rdpuririorlof graphne polvdel it wai vcry ditficuh ro dctcrrninc (hc

valucs ol cdbon vapour conccntration *hen diffcrcnt pow-dc.s wcrc proccsscd. Thcrclorc. accum(c fuucrcnc yiclddcpcidence \.enus cArlon vapour concenrarion, plas a

flame relocity and rotrtional tcmpcrarlle of C. radrcalshds not bccn discloscd. Howc!cr, qualitarire confinnationol kinetic nhdelol lnllcrcnc li)rmdLion has bccn achrovod.Lower nean rerrr|)ernNres of llanre rhar rcsulrcd in snallgradie.t lemperature licld And low flismd lclocit) lacili-rate lullerere synthesrs.

Imam

o

ottl

6

X3t;

rrme (ntn)

rk.16. HPI{: chnnuogrrn' (connosil BuctyF-p Jdlun'n. roluutr.r2r nm) ui rrnrd.d:... lrc'n p'e'si{t

of KSi gllphilc A\sigrdtio!: | : Cr,. :: Ci,O. l: C*,O., 4: (:i. 5: (ra o.6: (]a. ?: C.!.3: C" o. q,. 9 C!. l0r CM.

J Nanasci Nanotechnol. 7, 1-1s,2007

ro 2a 30 40

l,i*aE {rs prasma rczae i@!

tia. 17. Fullq.-nc J-'i.ld a I fuo.rior ol uial 'tisr

( non r..ozr.ol pl.Dnrd rrych. Hclintu o cir *.s 82%

E

11

Ftrllcrene PnrducLron b! th€ Arc rod rhc Radio-Fr.quenry Disohrge N4eliods

TrUe ltr. C.Dipansor !l l)C ,rrl l{F trsmr Acknowledgments: T}e uu(hrn! rhank rhe sutporl oftle Hungaflan Sclentlfi! Rsscaruh Furd (Proie.t No.T047360 and T0.16700) and drc Minjsky of scicncc andEnviro.mental Protection of Repuhlic of serbia (ProiecrNo. l4l0l5b)-

Reterences and Notes

0.1 t0

z,

4,

rl $.Kturo.J R rr.rdr S C Ollien R ICua mCR Lsnrr Le]. r,tr,a 1lll. r6? (]935)W K ds.rmff. r. D t.rnh. K. t"osr

'o)outos. iird D R Hrfl af.

H W Kro(o \ \\ \inl trrd S lt Brh. a_h fd 9t t2ti

H l4urrJ'rmr. S lomonrh J M |lt)rd. rnd Nt E Krrxk A,tNtuorlhA & drh.. N6llit!.rtt 17 1 \zOOa)

UJ

o

ltg,ltlE

b.en obtained lvhcr (hc axial distance fron $e no77le ofplasma lo.ch was 53-57 cm (6.1t9%).

Bascd on thc rcsulls prcscnled in Figure 17. one canconchdc thc zon! ol fullorcfc lormation $as 38 cnr

l(nrg. fhc rcs .ncc (Lmo oi carbo cLusters in this rypeof pla$na is aboul two o ors oi nag.irude larger tlrAn

thc rcsidencc timc of c rbc'n clusters tormed in ca$onlrc plaena lhe obtaincd ilara indicac drat tle synthe-sis of bigho iullcrcncs such ar CrlL, is quite possiblcThc derailed invesdgation ol collecbd lirlicrc.c soot (mass..pf.I.,merry and HPLC) has bccn rcfralci rhdr in dnd-

lyzed lullc.ene n lullcrcncs highcr (han Csd ha\l nor

crisrcd Th. most p.obablc rcason for the lack of highellnllerenes is rhe rransmuti ion ol hishcr fullerenes (Crrand hlgher) ln|o Ci and Cr in rhe tempcniure range ot200(|r000 K.i'

5. CONCLUSTON

I'r this work. coDp ntivc anAlysis of carbon a,c and car-bon .adio licqucncy phsnit duridg fullerere sy.rhe$s has

b@n reporrcd. The lerilication ofdevelopcd kinc(ic modclof frllerene formadon in hoth uscd plasma reactors has

bccn donc. tsaed on rhe obrained rcsulrs. it was roundthar carbon concenrration. velociLy of pldma nmc rndro(aronal temperarure atlcctcd lhc fullcrene )i€ld predom-inanll,y lt was found thal tho zone ol tullerene lbnnarondependcd on (he lype of sed flasma reactoF Fo. {rpcri(nefficrency of tullerene ibnrrAron, rolational lcmpcralurc olC. radlcals should be boul 1000K

h .rlna -r. rrn((,r lh( loD( ul lullere.re tcrnrticnwas I cm while

'n Rl: plasm rcac(or 38 cnr long The

rcsidencc Limc ol cdhon spccics in RF plasma rs abou(two ordcrs of magniludc lrrgcr rhan rhe rcsidence Limc oIcarhon species fonned iI arc plasma. Main ditfercnces .fI)C .nd RF fhnna sysrcms in lcrms of fullere.e synthesis

are summariz€d in T.rhlo lll.ln (his paper, yc hnve dernonsrrar..l fcasibiliry of large

scalc k,w cosr iullerene synthesis nr RF rhermrl tiasma

12

5. lt F: (itrl_ /']lrr r,J^r tt l!r.l4r /\ !4!. n (r99alM PoF,r. r,9,./rr F:i/k*r/r.\,2t t6? 7,<t

tr9vt)7, S Bosi. T Da Ros. C Spdlu(o. ir \1 ftib., ryzl CAr,r :13

tl, 1 ! w ts.r. Th( t-larlLhlr) sat hr.ttu.t 21\1999),. lS Shil YC Ch.o. Nl IrS[dg.C J Siu.atuC S Chror

sttn,\ tun tlnrt'r\ u 76. J4i (2t)t)l)ln.\\( r. D.,,/ 71nr.\t.,,r\d t e-!.

C StrrchJ-. rid r WrJl,lfl,l Pl)r ld, 6: 53j (19931

ll, D Afufus cv. J Bl,nuv A Bogda o!, C DylAcv V Kiturr!, rdA Kru$ikdr. a,l PA)r r9. l0l? 0194)

,2, T T And.^.n. P L D)-u. r W I)Jkc\. P KLJlirn. p F: ^nd6on.I Z Liu rnd R N Sl'cko . &.r 5!i /,rru,r 65 l3l0

T4t nar i. .t29 lt993lt.l. -f Brtr J FinJ D H.:c,n N pfindcr T Ruhl. H $t.nJr

N, \n hlr.i riR Schlogl ,!,, r1rlri I'1'\: Chd tO]L.111

15. F (im s txtJ R B Hurn! rn(t I s TnLn!. (:tun (tu\

16, N I Atks.luv rnd G A Dyuzlrrv. (1"rd 41. tllr 12001)17, A Sfslr. l Crrek, mLl \'I Olodrl. ltlt Nundtbt\ & Crtbo

^rid,vr&/!,: rr. r 1200s1

20. J R lloward J l- Irl.K'nn.n. Y Mrkrd!\kY A L Laieur rftlM l: Johnson- ritua .r52, llu (1991)

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22. H T.Lk.hrr. Nl Fuii$dn. M Arikawn M. D Drcn.r ind J MAllord. Otrrrn.ll. 3l I (2005).

23. L frLchef. Y Schwnh. F l-fiy (i flrnrnr L F p chihde irdD LrpLr^ 1n,,,, r3 rc7 {2000)

24. C w.nA. T liilrori Y Td'rk{ T Sxkufu. H TrkrlNr ]rdll Miiu. Trt'i r,r/, /r/,r 191r. (2001)

25, C wrng. ,\ lnrziki.l Shtdi Y. Te'0k. T Sak0h H Trliti{r.rnd H tfitu!. ?rm S,l/ thl !2 4l (20031

26, C Curr-Smch.z G Souct.A llulrko.J Beatrr"ij.ardD rrroui,r.i tht\. ch(n 3 \oa t9zltJ (2\t1t4)

2?. K nNhi. s Kasr!tr K F!u.r!. d t \'t\d'i.Jn. Appl Ptry I2r

28. R Duhm*ky: \. &zmrln{ryn !r'l A Etc$kii. c".t r !2. t06l

29. N r: ltun rnd J I Lrqow\ki. air,rd,10 919 (2002)

3U I ToJort,tia Nlrrk.v,i. Z Nli kov a. l Niihrl 7 Krnnr- L Gi.K foglrr P T Szrbo. mid I Szc)volgtL Lbrt Phrt l.!t l7A

l, lr F ChihrnLc /\ TLruss. J Alartrd \'1 D Drtnr. rnd R ES illel J rrlr C/r,, 97. 3696 (19931

fr'r{ r lr r\N \l J Hdl c lrnu|rnrA. I.* do*J.}. i,'d D r: Ki'rg I Ph\\ (:han.)7 tltu

J. Nanosci. Nanotechnot 7, 1 13.2007

Fnlicrcnc l'roduotn!' by rhc Arc and r|t Radio-Fruqusroy Dischaee Nlerhods

31, B Todorovia-Mrkovia 7 Nldrkoria, I ll.ha,. 7 Nikolia. .19, D \,1 Alirnis'.v. A A. Bolrl ov, (j. .\ D!uzh.v: rndz rr*a: I s/co.lgyi. E Kovir\, P schriu_ and s l-eir J,'/r)tr. A.A Kruelikor re.rr t'ht\ a2.234 \t9y7)D:

^ppt Pttt 19. \rA Q006). s0. C v D.n'hrv\ki Plryna Mrhlhtrgy.Iihoir, rNerdam O93s,

32. S (i Kin id D. TonEnut- P/trr ,lAr ,?r. 72.2a13 (19qr) O 2rif,3. Y Yanaaudin nd S. MlruFma. Cr.,r Phrr llt 2tt6. 1t6 51, D. l' Ar'anas-s. A A Bogdinov. c. Dyuzh*,. rnd a A

0993) Kruslikor'. ,noa ,ttar 7 er (1916).3,1- I }{anrym,a Md Y Y{uluchi. Crdn Pbi I2' 286 r4r (1998) 52. v ll shima,Dvi.h. I lt stuallikov. d I Trto'norsti.l !),BJ5. (; \bn Hcldcn, lvt. l Hsu. P R Kcmtcr md M f Boscre. Phr{ 71.669 r1r93)

, Lre', rrrr 95. 335 ll99l) 53, G I Suhjnin an,l O A. N(trhcv lDrii Mah. Jt.h ?hn. ta. AA36. G \nn Helden. M T llsu, N Gorrs. xrd M. T llo$crs. I /r\r 11991)

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c/r'r 99.r?r5(1991) 55, I Todororia lvlfkoria. z Md|Rlvii.l Moh.t rfulI srepvoslL.33. J Htrnrr. I L. Fyc. E. J. Rorkain!. and N{. l Jdrold. J PrrJ. Thc Ph}sics.flon zed CNls AIP Contc.!i.. lliaedrnls (2004).

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lubt, & c(thtn Ndnonrtrhtr 10 gt 12002) 098i)4:1, Z Nikolia, DiaincLdr l)lgilrl Aralyler Sofi$dc, v6n,n 20 (20113) 60, C G Plngger, J. O H.illnrhl A M Kcszlcr ard I- \emes,l2,l!ir, G Hdzberg Ir50 spdcrru ol DntLonic Mo rcules. znd tdr Nr* (rnir\ 12.6192 Q003)

nrl. van Nor f.Dd 61, ll. NLshiymr. T Snro. S lro. T Sr(). {fd S K niymr. H.,r,z/45. S ,\ 10rl i. P N ko .!1. w Ho m$ n C n Sco(.,4rrl Pirr / Md$ Iarva l/, '113 (2002)

70 l?512000) 62. \'! 1 llou.s. $b.knLot on Fnihr.^ in Los Tsmteftrure Phnk46. S Pelle.d. K yoko: O Votd. B Pokrzv$kx. rod J chr|j.llc. Dir{n.sL.s nI. Sa lan. S\yir7. bid (1999)

J P|'\s D Apr,l Prti 2r. 2850 (i996) 63, I1 Buchncr lL SclDbcfl. I tjhl.nb[sch, lnd K wittee, Ptr's,zt7. a Todororia'\'ldkolit. I Matko\ta. Z Mkolia Z Risrii. and Cne,nrry d Ptdnd Ptrftsrr3 t9. 34t t1999)

T \.nado$4, A,ll. NahnLet & Cutrn Naba ctur 12. G1 64 K Gluch S \laft labnc. o l:chr. B Coicina_ It scheic. and(t0o4) T D \ja.k, J. c]rnl Pt r l2l.2ll7 (201,4)

d& H kngc K Saiddq M RMrlirir! !nr,mdn c|.i7a.-/ /b1. 65. G. A l)yuTha and \| I Krm?4. Pltr Jdr.].lrJrr 16. |523 ( l99l ID:

^fl Ph$.11. to2411999). ft. R I cmss md M srundcrs. J

^n ch.d 5,a Il7. 1n.1! l2lrl,5j fi

@m

Rcccivcd: 27 January 2006. Rerised/Acccprcdr l0 May 2006. Ao

Io-m

J Nanos.i. Nanateahnal. 7, 1-1 3, 2007