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Iimpawu zemagneti ze-SrFe12O19 (SFO) i-hexaferrite enzima ilawulwa ngobudlelwane obunzima be-microstructure yayo, emisela ukufaneleka kwabo kwizicelo zemagnethi ezisisigxina.Khetha iqela le-nanoparticles ye-SFO efunyenwe nge-sol-gel ezenzekelayo yokutshisa i-synthesis, kwaye wenze ubunzulu be-X-ray ye-powder diffraction (XRPD) yesakhiwo somgca we-G (L) uhlalutyo lweprofayili yomgca.Ukusabalalisa ubungakanani be-crystallite obufunyenweyo bubonisa ukuxhomekeka okucacileyo kobukhulu kunye ne- [001] isalathiso kwindlela yokudibanisa, ekhokelela ekubunjweni kweekristali ezinqabileyo.Ukongezelela, ubukhulu be-SFO nanoparticles bunqunywe nguhlalutyo lwe-electron microscopy (TEM) yokudluliselwa, kunye nenani eliqhelekileyo leekristale kwiinqununu zaqikelelwa.Ezi ziphumo ziye zavavanywa ukuze zibonise ukubunjwa kwendawo enye ye-domain engaphantsi kwexabiso elibalulekileyo, kwaye umthamo wokuvuselela uvela kwimilinganiselo yemagnetization exhomekeke kwixesha, ejoliswe ekucaciseni inkqubo ye-magnetization eguqukayo yezinto ezinzima zemagneti.
Izixhobo zemagnethi zeNano-scale zinokubaluleka okukhulu kwezenzululwazi kunye nobuchwepheshe, kuba iipropathi zazo zemagneti zibonisa iindlela zokuziphatha ezahlukileyo kakhulu xa kuthelekiswa nobungakanani bevolumu yazo, ezisa iimbono ezintsha kunye nezicelo1,2,3,4.Phakathi kwezinto ezenziwe nge-nanostructured, i-M-type hexaferrite SrFe12O19 (SFO) ibe ngumgqatswa onomtsalane kwizicelo zemagnethi ezisisigxina.Ngapha koko, kwiminyaka yakutshanje, mninzi umsebenzi wophando owenziweyo malunga nokwenziwa kwezinto ezisekelwe kwi-SFO kwi-nanoscale ngokusebenzisa iindlela ezahlukeneyo zokudibanisa kunye neendlela zokulungisa ubungakanani, i-morphology, kunye ne-magnetic properties6,7,8.Ukongeza, ifumene ingqwalasela enkulu kuphando kunye nophuhliso lweenkqubo zokudibanisa utshintshiselwano9,10.I-anisotropy yayo ephezulu ye-magnetocrystalline (K = 0.35 MJ / m3) ejoliswe ecaleni kwe-c-axis ye-hexagonal lattice yayo i-11,12 isiphumo esithe ngqo sokulungelelaniswa okuyinkimbinkimbi phakathi kwe-magnetism kunye ne-crystal structure, i-crystallites kunye nobukhulu beenkozo, i-morphology kunye nokuthungwa.Ngoko ke, ukulawula ezi mpawu zingasentla sisiseko sokuhlangabezana neemfuno ezithile.Umzobo we-1 ubonisa iqela eliqhelekileyo lesithuba se-hexagonal P63 / mmc ye-SFO13, kunye nendiza ehambelana nokubonakaliswa kwesifundo sokuhlalutya iphrofayili yomgca.
Phakathi kweempawu ezihambelanayo zokunciphisa ubungakanani be-particle ye-ferromagnetic, ukubunjwa kwendawo enye ye-domain ngaphantsi kwexabiso elibalulekileyo kukhokelela ekunyuseni kwe-anisotropy yamagnetic (ngenxa yendawo ephezulu yommandla ukuya kumlinganiselo womthamo), okhokelela kwintsimi yokunyanzelisa14,15.Ummandla obanzi ongaphantsi komlinganiselo obalulekileyo (DC) kwizinto eziqinileyo (ixabiso eliqhelekileyo limalunga ne-1 µm), kwaye lichazwa yinto ebizwa ngokuba yisayizi ehambelanayo (DCOH)16: oku kubhekiselele kwindlela yomthamo omncinci wokukhutshwa kwemagnethi kwisayizi ehambelanayo. (DCOH) , Ukuchazwa njengomthamo wokusebenza (VACT) 14. Nangona kunjalo, njengoko kuboniswe kuMfanekiso 2, nangona ubukhulu bekristale buncinci kune-DC, inkqubo yokuguqula isenokungahambelani.Kwizinto ze-nanoparticle (NP), umthamo obalulekileyo wokuguqulwa kuxhomekeke kwi-viscosity magnetic (S), kunye nokuxhomekeka kwayo kumandla ombane kunika ulwazi olubalulekileyo malunga nenkqubo yokutshintsha kwe-NP magnetization17,18.
Ngaphezulu: Umzobo weSchematic of the evolution of the coercive field with particle size, ebonisa inkqubo yokuguqula imagnetization ehambelanayo (ethathwe kwi-15).I-SPS, i-SD, kunye ne-MD imele i-superparamagnetic state, i-domain enye, kunye ne-multidomain, ngokulandelanayo;I-DCOH kunye ne-DC zisetyenziselwa ukuhambelana kwedayamitha kunye nobukhulu obubalulekileyo, ngokulandelanayo.Ngezantsi: Imizobo yeengqungquthela zobukhulu obuhlukeneyo, ebonisa ukukhula kweekristale ukusuka kwikristale enye ukuya kwi-polycrystalline.kwayebonisa i-crystallite kunye nobungakanani besuntswana, ngokulandelelanayo.
Nangona kunjalo, kwi-nanoscale, imiba emitsha entsonkothileyo iye yaziswa, njengokusebenzisana okunamandla kwamagnetic phakathi kwamasuntswana, ukuhanjiswa kobungakanani, ubume besuntswana, ukuphazamiseka komhlaba, kunye nesalathiso se-axis elula ye-magnetization, zonke ezo zenza uhlalutyo lube ngumngeni19, 20 .Ezi zinto zichaphazela kakhulu ukuhanjiswa komqobo wamandla kwaye zifanele ukuqwalaselwa ngononophelo, ngaloo ndlela zichaphazela imowudi yokubuyisela umbane.Ngesi siseko, kubaluleke kakhulu ukuqonda ngokuchanekileyo ulungelelwaniso phakathi komthamo wemagnethi kunye ne-nanostructured ye-M-type hexaferrite SrFe12O19.Ngoko ke, njengenkqubo yomzekelo, sasebenzisa isethi ye-SFOs elungiselelwe yindlela ephantsi-phezulu ye-sol-gel, kwaye kutshanje yenze uphando.Iziphumo zangaphambili zibonisa ukuba ubukhulu be-crystallites buluhlu lwe-nanometer, kwaye, kunye nokuma kwe-crystallites, kuxhomekeke kunyango lokushisa olusetyenzisiweyo.Ukongezelela, i-crystallinity yeesampulu ezinjalo ixhomekeke kwindlela yokudibanisa, kwaye uhlalutyo olucacileyo luyafuneka ukucacisa ubudlelwane phakathi kwe-crystallites kunye nobukhulu be-particle.Ukuze kubonakaliswe obu budlelwane, ngohlalutyo lwe-electron microscopy (TEM) yothumelo oludityaniswe nendlela ye-Rietveld kunye nohlalutyo lweprofayili yomgca we-X-ray ye-powder diffraction yezibalo eziphezulu, i-crystal microstructure parameters (okt, i-crystallites kunye nobukhulu bamasuntswana, imilo) zahlalutywa ngononophelo. .XRPD) indlela.Ukubonakaliswa kwesakhiwo kujolise ekuqinisekiseni iimpawu ze-anisotropic ze-nanocrystallites ezifunyenweyo kunye nokuqinisekisa ukuba kunokwenzeka ukuhlalutya iphrofayili yomgca njengendlela eyomeleleyo yokubonakalisa ulwandiso oluphezulu kwi-nanoscale uluhlu lwezinto (i-ferrite).Kufunyaniswe ukuba umthamo-weighted crystallite ubungakanani unikezelo G(L) kakhulu kuxhomekeke ulwalathiso crystallographic.Kulo msebenzi, sibonisa ukuba iindlela ezongezelelweyo ziyafuneka ngokwenene ukukhupha ngokuchanekileyo iiparitha ezinxulumene nobukhulu ukuchaza ngokuchanekileyo ubume kunye neempawu zemagneti zesampulu zempuphu ezinjalo.Inkqubo ye-reverse magnetization yaphononongwa ukucacisa ubudlelwane phakathi kweempawu zemophological structure kunye nokuziphatha kwamagnetic.
Uhlalutyo lwe-Rietveld lwe-X-ray powder diffraction (XRPD) idatha ibonisa ukuba ubukhulu be-crystallite ecaleni kwe-c-axis bunokulungiswa ngonyango olufanelekileyo lobushushu.Ibonisa ngokuthe ngqo ukuba incopho yokwandisa okujongwe kwisampulu yethu kusenokwenzeka ukuba kungenxa yemilo yekristallili ye-anisotropic.Ukongeza, ukuhambelana phakathi komndilili wedayamitha ecazululwe nguRietveld kunye nomzobo we-Williamson-Hall (kwayekwiThebhile S1) ibonisa ukuba iikristale ziphantse zingabinaxinzelelo kwaye akukho deformation yesakhiwo.Ukuvela kwe-crystallite ubungakanani bokusabalalisa ngeendlela ezahlukeneyo kugxininise ingqalelo yethu kwisayizi efunyenweyo.Uhlalutyo alulula, kuba isampuli efunyenwe ngokutshiswa kwe-sol-gel iqulethwe ngamasuntswana angama-agglomerates ane-porous structure6,9, amashumi amabini ananye.I-TEM isetyenziselwa ukufunda ubume bangaphakathi besampulu yovavanyo ngokubanzi.Imifanekiso ye-brightfield eqhelekileyo ichazwe kwi-Figure 3a-c (ukufumana inkcazo ecacileyo yohlalutyo, nceda ubhekisele kwicandelo 2 lezinto ezongezelelweyo).Isampulu iqulathe amasuntswana anemilo yamaqhekeza amancinci.Iiplatelet zidibana ukuze zenze i-aggregates ene-porous yobukhulu obahlukeneyo kunye neemilo.Ukuze kuqikelelwe ubungakanani bokuhanjiswa kweeplatelet, indawo yamasuntswana angama-100 kwisampulu nganye yalinganiswa ngesandla kusetyenziswa isoftware ye-ImageJ.Ububanzi besangqa esilinganayo kunye nommandla we-particle efanayo njengoko ixabiso libalelwa kubukhulu bommeli weqhekeza ngalinye elilinganisiweyo.Iziphumo zeesampulu ze-SFOA, i-SFOB kunye ne-SFOC zishwankathelwe kwi-Figure 3d-f, kunye nexabiso le-diameter ephakathi nalo lixeliwe.Ukwandisa ubushushu bokucubungula kwandisa ubungakanani beengqungquthela kunye nobubanzi babo bokusabalalisa.Ukususela kuthelekiso phakathi kwe-VTEM kunye ne-VXRD (Itheyibhile 1), kunokubonwa ukuba kwimeko ye-SFOA kunye neesampuli ze-SFOB, inani eliqhelekileyo le-crystallites nge-particle libonisa uhlobo lwe-polycrystalline yale lamellae.Ngokwahlukileyo, umthamo we-particle ye-SFOC ifaniswa nomthamo we-crystallite oqhelekileyo, obonisa ukuba ininzi ye-lamellae yi-crystals enye.Sibonisa ukuba ubukhulu obubonakalayo be-TEM kunye ne-X-ray diffraction yahlukile, kuba ekugqibeleni, silinganisa ibhloko edibeneyo yokusasazeka (inokuba yincinci kune-flake eqhelekileyo): Ukongeza, impazamo encinci yokuqhelaniswa kwezi zisasazo. imimandla iya kubalwa ngodiffraction .
Imifanekiso ye-TEM eqaqambileyo ye (a) ye-SFOA, (b) ye-SFOB kunye (c) ne-SFOC ibonisa ukuba yenziwe ngamasuntswana anemilo efana nepleyiti.Unikezelo lobungakanani obuhambelanayo buboniswa kwihistogram yendawo yolawulo (df).
Njengoko siye saqaphela kuhlalutyo lwangaphambili, i-crystallites kwisampuli ye-powder yangempela yenza inkqubo ye-polydisperse.Ekubeni indlela ye-X-ray inomdla kakhulu kwibhloko edibeneyo yokuqhawula, uhlalutyo olucokisekileyo lwedatha ye-powder diffraction iyadingeka ukuchaza i-nanostructures emihle.Apha, ubungakanani beekristale kuxoxiswana ngazo ngophawu lomsebenzi wokusabalalisa ubungakanani bekristallite enobunzima bevolumu G(L) 23, obunokutolikwa njengoxinaniso olunokwenzeka lokufumana iikristale zemilo ecingelwayo kunye nobukhulu, kwaye ubunzima bayo buhambelana yona.Umthamo, kwisampulu ehlalutyiweyo.Ngomfanekiso we-prismatic crystallite, umlinganiselo we-volume-weighted crystallite ubukhulu (umyinge wecala lobude kwi- [100], [110] kunye ne- [001] imiyalelo) ingabalwa.Ngoko ke, sikhethe zonke iisampulu ezintathu ze-SFO ezinobungakanani obuhlukeneyo obuhlukeneyo ngendlela ye-anisotropic flakes (jonga i-Reference 6) ukuvavanya ukuphumelela kwale nkqubo ukufumana ubungakanani obuchanekileyo be-crystallite ukusabalalisa izinto ze-nano-scale.Ukuze kuhlolwe i-anisotropic orientation ye-crystallites ye-ferrite, uhlalutyo lweprofayili yomgca lwenziwa kwidatha ye-XRPD yeengqungquthela ezikhethiweyo.Iisampuli ze-SFO ezivavanyiweyo azizange ziqulethe i-diffraction elula (ecocekileyo) ephezulu ukusuka kwisethi efanayo yeeplanethi ze-crystal, ngoko kwakungenakwenzeka ukwahlula igalelo lokwandisa umgca ukusuka kubukhulu kunye nokuphazamiseka.Ngexesha elifanayo, ukwandiswa okubonwayo kwemigca ye-diffraction kunokwenzeka ngakumbi ngenxa yesiphumo sobukhulu, kwaye ubume be-crystallite obuqhelekileyo buqinisekisiwe ngokuhlalutya imigca emininzi.Umzobo we-4 uthelekisa ubungakanani bomthamo wexabiso lekristale umsebenzi wokusabalalisa ubungakanani G (L) ecaleni kwendlela echaziweyo yecrystallographic.Uhlobo oluqhelekileyo lokusabalalisa ubungakanani be-crystallite yi-lognormal distribution.Olunye uphawu lwazo zonke izinikezelo zobungakanani obufunyenweyo kukungafani kwazo.Kwiimeko ezininzi, olu lwabiwo lunokuthi lubangelwe kwinkqubo ethile echaziweyo yokwakheka kwamasuntswana.Umahluko phakathi komlinganiselo obaliweyo wencopho ekhethiweyo kunye nexabiso elikhutshwe kwi-Rietveld yokucokisa ingaphakathi kuluhlu olwamkelekileyo (uthathela ingqalelo ukuba iinkqubo zokulinganisa isixhobo zahlukile phakathi kwezi ndlela) kwaye iyafana naleyo ukusuka kwiseti ehambelanayo yeenqwelomoya nge I-Debye Ubungakanani obuqhelekileyo obufunyenweyo buhambelana ne-equation ye-Scherrer, njengoko kuboniswe kwiThebhile 2. Umkhwa we-volume average crystallite ubungakanani beendlela ezimbini ezahlukeneyo zokufanisa zifana kakhulu, kwaye ukuphambuka kobungakanani obupheleleyo kuncinci kakhulu.Nangona kunokubakho ukungavisisani kunye no-Rietveld, umzekelo, kwimeko ye-(110) imbonakalo ye-SFOB, inokunxulumana nomiselo oluchanekileyo lwemvelaphi kumacala omabini omboniso okhethiweyo kumgama we-1 degree 2θ kwindawo nganye. ulwalathiso.Nangona kunjalo, isivumelwano esigqwesileyo phakathi kwetekhnoloji ezimbini siqinisekisa ukufaneleka kwendlela.Ukusuka kuhlalutyo lwencopho yokwandisa, kuyacaca ukuba ubungakanani kunye [001] buxhomekeke ngokuthe ngqo kwindlela yokudibanisa, okukhokelela ekubunjweni kweekristale ezinqabileyo kwi-SFO6,21 eyenziwe yi-sol-gel.Olu phawu luvula indlela yokusetyenziswa kwale ndlela yokuyila iinanocrystals ezinemilo ekhethiweyo.Njengoko sonke sisazi, ubume bekristale obuntsonkothileyo be-SFO (njengoko kubonisiwe kuMfanekiso 1) ngundoqo wokuziphatha kwe-ferromagnetic ye-SFO12, ngoko ke imilo kunye neempawu zobungakanani zinokuhlengahlengiswa ukuze kulungiswe uyilo lwesampulu yezicelo (ezifana nesigxina. ezinxulumene nemagnethi).Sibonisa ukuba uhlalutyo lobungakanani be-crystallite yindlela enamandla yokuchaza i-anisotropy yeemilo ze-crystallite, kwaye iqinisa ngakumbi iziphumo ezifunyenwe ngaphambili.
(a) SFOA, (b) SFOB, (c) SFOC ekhethiweyo reflection (100), (110), (004) volume weighted crystallite ubukhulu ukuhanjiswa G(L).
Ukuze uvavanye ukuphumelela kwenkqubo yokufumana ubungakanani obuchanekileyo be-crystallite ukusabalalisa izinto ze-nano-powder kwaye uyisebenzise kwii-nanostructures eziyinkimbinkimbi, njengoko kuboniswe kwi-Figure 5, siye saqinisekisa ukuba le ndlela iyasebenza kwizinto eziphathekayo ze-nanocomposite (amaxabiso abizayo).Ukuchaneka kwetyala kuqulunqwe ngu-SrFe12O19/CoFe2O4 40/60 w/w %).Ezi ziphumo zihambelana ngokupheleleyo nohlalutyo lweRietveld (jonga i-caption ye-Figure 5 ukuthelekisa), kwaye xa kuthelekiswa nenkqubo yesigaba esisodwa, i-SFO nanocrystals inokugqamisa i-morphology efana neplate.Ezi ziphumo zilindeleke ukuba zisebenzise uhlalutyo lweprofayili yomgca kwiinkqubo ezinzima ngakumbi apho izigaba ezininzi ze-crystal ezihlukeneyo zinokungena ngaphandle kokulahlekelwa ulwazi malunga nezakhiwo zabo.
Ubungakanani bomthamo we-crystallite ukusabalalisa ubungakanani be-G (L) yemiboniso ekhethiweyo ye-SFO ((100), (004)) kunye ne-CFO (111) kwii-nanocomposites;ukuthelekisa, amaxabiso okuhlalutya eRietveld ahambelanayo yi-70 (7), 45 (6) kunye ne-67 (5) nm6.
Njengoko kuboniswe kwi-Figure 2, ukuzimisela kobungakanani besizinda samagnetic kunye noqikelelo oluchanekileyo lomthamo womzimba sisiseko sokuchaza iinkqubo ezinzima ezinjalo kunye nokuqonda ngokucacileyo ukusebenzisana kunye nomyalelo wesakhiwo phakathi kweengqungquthela zamagnetic.Kutshanje, indlela yokuziphatha yamagnetic yeesampulu ze-SFO ifundwe ngokweenkcukacha, ingqwalasela eyodwa kwinkqubo yokuguqula i-magnetization, ukuze kufundwe icandelo elingenakuguqulwa le-magnetic susceptibility (χirr) (Umfanekiso S3 ngumzekelo we-SFOC)6.Ukuze sifumane ukuqonda okunzulu kwendlela yokuguqula i-magnetization kule nanosystem esekwe kwi-ferrite, senze umlinganiselo wokuphumla wamagnetic kwintsimi engasemva (HREV) emva kokuzaliswa kwicala elinikiweyo.Qwalasela \(M\left(t\right)\proptoSln\left(t\right)\) (jonga uMfanekiso 6 kunye nemathiriyeli eyongezelelweyo ngeenkcukacha ezithe vetshe) uze ufumane umthamo wokuvula (VACT).Ekubeni inokuchazwa njengomthamo omncinci wezinto eziphathekayo ezinokuguqulwa ngokuhambelanayo kwisiganeko, le parameter imele umthamo "wemagnetic" obandakanyekayo kwinkqubo yokubuyisela umva.Ixabiso lethu le-VACT (jonga i-Table S3) ihambelana ne-sphere enobubanzi obumalunga ne-30 nm, echazwa njenge-diameter ehambelanayo (i-DCOH), echaza umda ophezulu wokuguqulwa kwemagnetization yenkqubo ngokujikeleza okuhambelanayo.Nangona kukho umahluko omkhulu kumthamo womzimba wamasuntswana (i-SFOA iphinda-phindwe ka-10 kune-SFOC), la maxabiso ahlala aguquguquka kwaye amancinci, abonisa ukuba indlela yokuguqula imagnetization yazo zonke iinkqubo ihlala ifana (iyangqinelana noko sikubangayo. yinkqubo yommandla omnye) 24 .Ekugqibeleni, i-VACT inomthamo omncinci womzimba omncinci kune-XRPD kunye nohlalutyo lwe-TEM (i-VXRD kunye ne-VTEM kwi-Table S3).Ngoko ke, sinokugqiba ukuba inkqubo yokutshintsha ayenzeki kuphela ngokujikeleza okuhambelanayo.Qaphela ukuba iziphumo ezifunyenwe ngokusebenzisa iimagnetometers ezahlukeneyo (Figure S4) zinika amaxabiso afanayo eDCOH.Kule nkalo, kubaluleke kakhulu ukucacisa i-diameter ebalulekileyo ye-particle domain particle (DC) ukwenzela ukuba unqume eyona nkqubo ifanelekileyo yokubuyisela umva.Ngokohlahlelo lwethu (jonga imathiriyeli eyongezelelweyo), sinokucinga ukuba i-VACT efunyenweyo ibandakanya indlela yokujikeleza engahambelaniyo, kuba i-DC (~0.8 µm) ikude kakhulu kwi-DC (~0.8 µm) yamasuntswana ethu, oko kukuthi, Ukwakhiwa kweendonga ze-domain ayikho Emva koko ifumene inkxaso eyomeleleyo kwaye yafumana uqwalaselo olulodwa lwesizinda.Esi siphumo sinokuchazwa ngokuqulunqwa kwesizinda sokusebenzisana25, 26. Sicinga ukuba i-crystallite enye ithatha inxaxheba kwi-domain yentsebenziswano, eyandisa kwiinqununu ezidibeneyo ngenxa ye-microstructure edibeneyo yezi zinto 27,28.Nangona iindlela ze-X-ray zinovakalelo kuphela kwi-microstructure emihle yemimandla (i-microcrystals), imilinganiselo yokuphumla yamagnetic inika ubungqina bezinto eziyinkimbinkimbi ezinokuthi zenzeke kwi-nanostructured SFOs.Ngoko ke, ngokulungisa ubukhulu be-nanometer yeenkozo ze-SFO, kunokwenzeka ukukhusela ukutshintshela kwinkqubo yokuguqulwa kwe-multi-domain, ngaloo ndlela kugcinwe ukunyanzeliswa okuphezulu kwezi zinto.
(a) Igophe lemagneti elixhomekeke kwixesha le-SFOC elilinganiswe kwintsimi eyahlukileyo yamaxabiso e-HREV emva kokuzaliswa kwi-5 T kunye ne-300 K (echazwe ecaleni kwedatha yovavanyo) (imagnetization iqheleke ngokobunzima besampulu);ukucaca, I-inset ibonisa idatha yovavanyo lwe-0.65 T intsimi (isangqa esimnyama), esineyona nto ifanelekileyo (umgca obomvu) (i-magnetization iqheleke kwixabiso lokuqala M0 = M (t0));(b) i-viscosity magnetic ehambelanayo (S) yinguqu ye-SFOC A umsebenzi webala (umgca sisikhokelo seso);(c) isikimu sesixhobo sokuvula esineenkcukacha zesikali sobude bomzimba/nobuzibuthe.
Ngokubanzi, ukuguqulwa kwemagneti kunokuthi kwenzeke ngothotho lweenkqubo zasekhaya, ezinje ngodonga lwedomeyini yodonga, ukusasazwa, kunye nokuphina kunye nokungaphini.Kwimeko ye-single-domain particles ferrite, i-activation mechanism i-nucleation-mediated kwaye ibangelwa yinguqu yemagnetization encinci kunomthamo wokuguqulwa kwamagnetic (njengoko kubonisiwe kwi-Figure 6c) 29.
Umsantsa phakathi kwemagnethi ebalulekileyo kunye nobubanzi bomzimba kuthetha ukuba imowudi engahambelaniyo sisiganeko esihambelanayo sokuguqulwa kwesizinda semagnethi, esinokubangelwa kukungahambelani kwezinto eziphathekayo kunye nokungalingani komphezulu, okuye kunxulumane xa ubungakanani besuntswana bunyuka ngama-25, okukhokelela ekuphambukeni imo yemagnetization efanayo.
Ngoko ke, sinokugqiba ukuba kule nkqubo, inkqubo yokuguqula i-magnetization inzima kakhulu, kwaye iinzame zokunciphisa ubungakanani kwisikali se-nanometer sidlala indima ephambili kwintsebenziswano phakathi kwe-microstructure ye-ferrite kunye ne-magnetism..
Ukuqonda ubudlelwane obuntsonkothileyo phakathi kwesakhiwo, ifom kunye nemagnethi sisiseko sokuyila kunye nokuphuhlisa usetyenziso lwexesha elizayo.Uhlalutyo lweprofayili yomgca wepatheni ekhethiweyo ye-XRPD ye-SrFe12O19 iqinisekisile i-anisotropic shape ye-nanocrystals efunyenwe yindlela yethu yokudibanisa.Ukudibanisa nohlalutyo lwe-TEM, i-polycrystalline nature yale ngqungquthela ibonakaliswe, kwaye emva koko yaqinisekiswa ukuba ubungakanani be-SFO ephononongwe kulo msebenzi buphantsi kunomlinganiselo obalulekileyo wesizinda esisodwa, nangona ubungqina bokukhula kwe-crystallite.Ngesi siseko, siphakamisa inkqubo ye-magnetization engenakuguqulwa esekelwe ekubunjweni kwesizinda sokusebenzisana esiqulunqwe ngamakristali adibeneyo.Iziphumo zethu zibonakalisa ulungelelwaniso olusondeleyo phakathi kwe-particle morphology, i-crystal structure kunye nobukhulu be-crystallite obukhoyo kwinqanaba le-nanometer.Olu phononongo lujolise ekucaciseni inkqubo yokubuyisela umbane wemagnethi enzima ye-nanostructured magnetic materials kunye nokumisela indima yeempawu ze-microstructure kwisiphumo sokuziphatha kwamagnetic.
Iisampulu zenziwa kusetyenziswa i-citric acid njenge-agent ye-chelating / i-fuel ngokwendlela yokutshisa i-sol-gel ezenzekelayo, echazwe kwi-Reference 6. Iimeko zokudibanisa zaye zaphuculwa ukufumana ubukhulu obuthathu obuhlukeneyo beesampuli (SFOA, SFOB, SFOC) efunyenwe ngonyango olufanelekileyo lwe-annealing kumaqondo okushisa ahlukeneyo (1000, 900, kunye ne-800 ° C, ngokulandelanayo).Itheyibhile S1 ishwankathela iipropati zemagneti kwaye zifumanisa ukuba ziyafana.I-nanocomposite SrFe12O19/CoFe2O4 40/60 w/w% nayo yalungiswa ngendlela efanayo.
Ipatheni ye-diffraction yalinganiswa kusetyenziswa i-CuKα radiation (λ = 1.5418 Å) kwi-Bruker D8 powder diffractometer, kunye nobubanzi be-slit detector bubekwe kwi-0.2 mm.Sebenzisa i-counter ye-VANTEC ukuqokelela idatha kwi-2θ uluhlu lwe-10-140 °.Iqondo lobushushu ngexesha lokurekhoda idatha ligcinwe kwi-23 ± 1 °C.Ukubonakaliswa kulinganiswa ngetekhnoloji yenyathelo kunye ne-scan, kwaye ubude benyathelo bazo zonke iisampuli zovavanyo ngu-0.013 ° (2theta);Ixabiso eliphezulu lencopho yomgama womlinganiselo ngu-2.5 kunye + 2.5 ° (2theta).Kwincopho nganye, i-quanta ye-106 iyonke ibalwa, ngelixa umsila kukho malunga ne-3000 quanta.Iincopho ezininzi zokulinga (zahlulwe okanye zadityaniswa ngokuyinxenye) zikhethelwe uhlalutyo olongezelelweyo ngaxeshanye: (100), (110) kunye (004), ezenzeke kwi-engile ye-Bragg kufuphi ne-Bragg angle yomgca wokubhalisa we-SFO.Ubunzima bokulinga bulungiswe kwi-Lorentz polarization factor, kwaye imvelaphi yasuswa ngotshintsho olucingelwayo lomgca.Umgangatho we-NIST we-LaB6 (NIST 660b) wasetyenziselwa ukulinganisa isixhobo kunye nokwandiswa kwespectral.Sebenzisa i-LWL (i-Louer-Weigel-Louboutin) indlela ye-deconvolution 30,31 ukufumana imigca ecocekileyo ye-diffraction.Le ndlela iphunyezwa kwinkqubo yohlalutyo lweprofayili PROFIT-software32.Ukusuka ekufakweni kwedatha yobungakanani obulinganisiweyo besampulu kunye nomgangatho kunye nomsebenzi weVoigt wepseudo, umgca ochanekileyo wecontour f(x) uyacatshulwa.Umsebenzi wonikezelo lobungakanani G(L) umiselwa kuf(x) ngokulandela inkqubo ethiwe thaca kwiReferensi 23. Ukufumana iinkcukacha ezithe vetshe, nceda ujonge imathiriyeli eyongezelelweyo.Njengokongeza kuhlalutyo lweprofayili yomgca, inkqubo ye-FULLPROF isetyenziselwa ukwenza uhlalutyo lweRietveld kwidatha ye-XRPD (iinkcukacha zinokufumaneka kwi-Maltoni et al. 6).Ngamafutshane, kwimodeli yaseRietveld, iincopho ze-diffraction zichazwa ngumsebenzi oguquliweyo weThompson-Cox-Hastings pseudo Voigt.Ucokiso lweLeBail lwedatha lwenziwe kumgangatho we-NIST LaB6 660b ukubonisa igalelo lesixhobo ekwandiseni ubuninzi.Ngokutsho kwe-FWHM ebaliweyo (ububanzi obugcweleyo kwisiqingatha sobunzulu bencopho), i-equation ye-Debye-Scherrer ingasetyenziselwa ukubala ubungakanani be-volume-weighted average ye-domain ye-crystalline yokusasazeka:
Apho u-λ bububude bemitha ye-X-reyi, i-K yimilo factor (0.8-1.2, idla ngokulingana no-0.9), kunye no-θ yi-engile ye-Bragg.Oku kusebenza ku: umboniso okhethiweyo, isethi ehambelanayo yeendiza kunye nomzekelo wonke (10-90 °).
Ukongezelela, i-microscope ye-Philips CM200 esebenza kwi-200 kV kwaye ixhotyiswe nge-LaB6 filament yayisetyenziselwa uhlalutyo lwe-TEM ukufumana ulwazi malunga ne-particle morphology kunye nokusabalalisa ubungakanani.
Umlinganiselo wokuphumla we-Magnetization wenziwa zizixhobo ezibini ezahlukeneyo: Inkqubo yokulinganisa iPropati yePhysical (PPMS) ukusuka kwi-Quantum Design-Vibrating Sample Magnetometer (VSM), exhotywe nge-9 T superconducting magnet, kunye ne-MicroSense Model 10 VSM ene-electromagnet.Intsimi yi-2 T, isampuli ihluthelwe kwintsimi (μ0HMAX: -5 T kunye ne-2 T, ngokulandelelana kwisixhobo ngasinye), kwaye emva koko intsimi ye-reverse (HREV) isetyenziselwa ukuzisa isampuli kwindawo yokutshintsha (kufuphi neHC ), kwaye ke Ukubola kwemagneti irekhodwa njengomsebenzi wexesha kwimizuzu engama-60.Umlinganiselo wenziwa kwi-300 K. Umthamo wokuvula ohambelanayo uvavanywa ngokusekelwe kuloo maxabiso alinganisiweyo achazwe kwizinto ezongezelelweyo.
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