Magnetic nanoparticles - fabrication, analysis and application (150030)














Mgntc Nn Prtcls - Fbrctn, nlyss nd pplctn

(ssy)



ntrductn


Snc th bgnnng f ths cntury, 2000, scnc nd ngnrng hs sn rpd ncrs n ntrst fr mtrls t th nn-scl. n fct, sttstcl dt frm Lux Rsrch, nc. shws tht wrldwd spndng n rsrch nd dvlpmnt f nn-tchnlgy s n xcss f $8 blln [1]. Th Untd Stts gvrnmnt ln s spndng vr $1 blln nnully [1]. Nn-mtrls hv ttrctd such strng ntrst bcus f th physcl, lctrnc, nd mgntc prprts rsultng frm thr quntum sz [2]. Th ptntl fr nn-tchnlgy s mmnsly dvrs wth ptntl pplctns n th flds f lctrncs, bmdcl dvcs, nrgy pplctns, mltry uss, nd wst mngmnt [2]. Nn-mtrls culd b utlzd t dsgn nn-trnsstrs, t dvlp nd dlvr mdcns fr lclly trtng dsss nd lmnts wthn th bdy, nd fr th crtn nw g wpns nd rmr fr mltry pplctns [3]. Ultmtly, nn-tchnlgy hs th ptntl t ffr nw, nxpnsv, nd mr ffcnt mtrls fr grtr rng f pplctns thn chvbl by bulk mtrls tdy. Wthn th fld f nn-mtrls undr wrldwd rsrch s th subst f mgntc nn-mtrls. Ths ppr wll dscuss th bttm-up synthss f mgntc nn-prtcls v thrml dcmpstn f mtl-crbnyl cmplxs, dscrb sm f th mthds usd t chrctrz mgntc prtcls, nd dscuss currnt rsrch fr pplctn f ths prtcls.



Synthss


Thr r mny tchnqus fr th synthss f mgntc nn-prtcls ncludng: mcr-mulsn, rductn f mtl-slts, gs-phs rductn f mtl cmplxs, thrmlyss f mtl-plymr cmplxs, nd thrml dcmpstn f mtl-crbnyl cmplxs. n ths ppr, th thrml dcmpstn f mtl-crbnyl wll b dscussd bcus t s tchnqu whch hs succssfully bn utlzd t synthsz mgntc nn-prtcls. Mtl-crbnyl cmplxs r cmmrclly vlbl prduct nd hv bn usd n th pst fr prprtn f cblt nd rn bsd ctlysts, mkng thm rdly pplcbl fr usg n synthss f mgntc nn-prtcls [2].

n ths synthss tchnqu, th fundmntl gl s t prduc tms n slutn, whch quckly nd spntnusly frmult nt nn-prtcls. Mnwhl, cntrllng thr sz nd shp by utlzng surfctnt, whch wll strngly dsrb nt th surfc f th nn-prtcls, prvds stblzng cp lyr nd smultnusly srvs s hndrnc fr th bndng f mr tms nt th nn-prtcl, hnc prvntng furthr grwth [4]. Th mtl-crbnyl pr-cursr srvs t prvd th mtl tms, th crdntng rgnc slvnt prvds mdum fr dsslutn, nd th surfctnt srvs t cntrl grwth nd mrphlgy. mtl-crbnyl cmplx s njctd nt n rgnc crdntng mxtur t lvtd tmprturs, whch lds t th brkdwn f th mtl-crbnyl cmplx nt ncpsultd mtl nn-prtcls wth lqud nd gsus by-prducts. n th xprmntl wrk f Yng t l. cblt ctcrbnyl (C2(C)8) ws njctd nt n rgnc crdntng mxtur md up f dchlrbnzn (C6H4Cl2), lc cd (C18H342), nd trphnylphsphn (C18H15P) t tmprtur f 220 C. n ths xmpl, dchlrbnzn s rgnc crdntng slvnt whch srvs t prvd mdum fr dsslutn f th cblt ctcrbnyl. nc dsslvd, nucltn spntnusly ccurs nd th mxtur f trphnylphsphn nd lc cd r usd s surfctnts whch srv t stblz th nucltd nn-prtcls. Th wrk f Yng t l. yldd sphrcl cblt nn-prtcls whch r 6-8 nm n vrg sz s shwn n Fgur 1 [5].


Fgur 1: TM mg f 2-D Suprlttc f C Nn-prtcls nd Hstgrm f vrg Sz = 7.2 0.5nm [5]


Punts t l. n thr xprmntl wrk ls usd cblt ctcrbnyl s prcursr nd dsslvd t n dchlrbnzn. Hwvr, rthr thn mplyng mxtur f lc cd nd trphnylphsphn s surfctnt, thy utlzd lc cd nd trctylphsphn xd (TP). By chngng th surfctnt, Punts t l. prducd rd shpd cblt nn-prtcls rngng n sz frm 4x25 nm t 4x75 nm n lngth by wdth [4]. Fgur 2 dsplys trnsmssn lctrn mcrscp (TM) rsults f Punts t l.


Fgur 2: ssmbls f 4 x 75 nm hcp-C Nn-rds (Br = 100 nm) [4].



Chrctrztn: Gmtrc nd Mgntc


n rdr t prprly chrctrz mgntc nn-prtcls nd grsp n undrstndng f thr prprts: gmtrc nd mgntc nfrmtn s f ssnc [6]. Gmtrc prmtrs nclud: sz, shp, bnd lngths, cmpstn, nd crystl structur, whrs th crtcl mgntc prmtrs r: mgntc mmnts, sturtn mgntztn, rmnnt mgntztn, crcvty, nd blckng tmprtur [6]. n ths ppr x-ry dffrctn (XRD) nd trnsmssn lctrn mcrscpy wll b dscussd fr gmtrc chrctrztn nd supr cnductng quntum ntrfrnc dvc (SQUD) mgntmtry fr mgntc chrctrztn.

X-ry Dffrctn (XRD)

n XRD, dffrctn ccurs whn smpl s rrdtd wth lctrmgntc rdtn, n ths cs X-rys, nd thr s ntrctn wth structur whr th rpt dstnc s n th sm rdr s th wvlngth f th lctrmgntc rdtn [7]. Th wvlngths f X-rys r ngstrms n mgntud, whch s n th rng f th rpt dstnc n mst crystlln sld mtrls [7]. Dffrctn ccurs bsd n Brggs lw, whch s shwn n qutn 1, whr n s n ntgr, λ s th wvlngth, d s th rpt dstnc, nd θ s th ngl f dffrctn.


qutn 1


Th utput frm XRD nlyss ylds plt, whch shws ntnsty vrsus dffrctn ngl, s shwn n Fgur 3. Frm ths n cn dtrmn th crystllgrphc plns tht r bng dffrctd nd snc th wvlngth nd dffrctn ngl s knwn, usng Brggs lw th rpt dstnc, d, cn b clcultd, whch cn b utlzd t crt mp f th crystl structur. ltrntvly, cllctn f stndrds cn b utlzd t cmpr th pks n th dffrctgrm wth ltrtur vlus, llwng n t dntfy crystl plns. Furthrmr, th qupmnt cn b cnfgurd t hv dtctr t msur X-ry bsrptn. Ths dtctr hs bn utlzd n th wrk f Hrms t l [6]. ch lmnt hs unqu bsrptn spctrum s utlzng X-ry dffrctn nd bsrptn lmntl dntfctn s btnd s wll s th rpt dstnc. Schvchnk t l, utlzd XRD n rdr t vlut pk brdnng wth sz dcrs nd thr rsults r shwn n Fgur 3.


Fgur 3. Sz-dpndnt XRD Pttrn f CPt3 Nn-crystls [13].


Trnsmssn lctrn Mcrscpy (TM)

t s pssbl t utlz n XRD quppd wth X-ry bsrptn dtctr t xtrct prtcl sz nd shp dt, hwvr, trnsmssn lctrn mcrscp s bttr tl fr xtrctn f sz nd shp dt bcus t ylds rl mgs frm whch msurmnts cn b md.

n trnsmssn lctrn mcrscp, n lctrn bm, fcusd by lctrmgntc lnss, s trnsmttd thrugh thn smpl f nn-prtcls [8]. Usng brght-fld dtctrs, whch cptur trnsmttd lctrns nd drk-fld dtctrs tht cptur bck-scttrd lctrns, n mg s gnrtd. Dpndng n th cnfgurtn nd cpblts f th TM, rslutn f 2 ngstrms cn b chvd, llwng dqut mg cptur f nn-prtcls [8]. Fgur 4 dsplys TM mg f gld nn-prtcls wth szs lss thn 20 nn-mtrs.


Fgur 4. TM mg f Nn-prtcls f Gld [4].


Suprcnductng Quntum ntrfrnc Dvc Mgntmtry (SQUD)

suprcnductng quntum ntrfrnc dvc (SQUD) s usd t msur vry wk mgntc sgnls, whch s xtrmly vlubl fr mgntc nn-prtcl nlyss. Th SQUD s md up f tw Jsphsn junctns. Jsphsn junctn s md up f tw suprcnductrs whch r sprtd by thn nsultng lyr, whch llws lctrns t crss thrugh [9]. Th flw f lctrns crss th thn nsultng lyr s knwn s th Jsphsn currnt nd s xtrmly snstv t mgntc flds [9]. SQUD msurs mgntc sgnls n th rdr f 10-9 Tsl nd lss [9].

Yng t l., n thr xprmntl wrk, utlzd SQUD t cptur hystrss bhvr f dffrntly prprd cblt nn-prtcl smpls t tw dffrnt tmprturs, s shwn n Fgur 5.


Fgur 5: Hystrss Lp f Pwdr f C Nn-prtcls t 250 K nd 10 K [5].



pplctns n R&D


Mgntc nn-prtcl pplctns r bng nvstgtd n multpl dscplns frm bmdcl snsrs, drug dlvry, mgntc rsnnc mgng, dt strg, nn-lctrncs, tc. Tw pplctns, whch r bng hvly nvstgtd by svrl rsrch grups, r: dtxfctn f cntmntd prsnnl fr th mltry nd drug dlvry nd trtmnt. Currnt tchnqus n bth f ths flds r vry lmtd nd mnmlly rbust nd nn-tchnlgy hs th ptntl t nhnc th cpblts n bth flds mmnsly.

Dtxfctn f Cntmntd Prsnnl Mltry






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