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Izici kazibuthe ze-SrFe12O19 (SFO) i-hexaferrite eqinile zilawulwa ubudlelwano obuyinkimbinkimbi be-microstructure yayo, enquma ukuhambisana kwazo nezinhlelo zokusebenza zikazibuthe unomphela.Khetha iqembu lama-nanoparticles e-SFO atholwe ngokuhlangana kwe-sol-gel okuzenzakalelayo, futhi wenze uhlaziyo olujulile lwesakhiwo se-X-ray powder diffraction (XRPD) ngokuhlaziywa kwephrofayela yomugqa we-G(L).Ukusatshalaliswa kosayizi we-crystallite okutholiwe kuveza ukuncika okusobala kosayizi eduze nesiqondiso se- [001] endleleni yokuhlanganisa, okuholela ekwakhekeni kwamakristalu angenalutho.Ukwengeza, ubukhulu be-SFO nanoparticles bunqunywe ukuhlaziywa kwe-electron microscopy (TEM), futhi isilinganiso senani lamakristalu ezinhlayiyeni zalinganiselwa.Le miphumela iye yahlolwa ukuze ifanekise ukwakheka kwezizinda zesizinda esisodwa ngaphansi kwenani elibalulekile, futhi ivolumu yokuvula itholakala ezilinganisweni zamagnetization ezincike esikhathini, okuhloswe ngazo ukucacisa inqubo ye-magnetization ehlanekezelwe yezinto eziqinile kazibuthe.
Izinto zikazibuthe ze-Nano-scale zinokubaluleka okukhulu kwezesayensi nobuchwepheshe, ngoba izakhiwo zazo kazibuthe zibonisa ukuziphatha okuhluke kakhulu uma kuqhathaniswa nosayizi wevolumu yazo, okuletha imibono emisha kanye nezinhlelo zokusebenza1,2,3,4.Phakathi kwezinto ezenziwe nge-nanostructured, i-M-type hexaferrite SrFe12O19 (SFO) isiphenduke ikhandidethi elikhangayo lezinhlelo zokusebenza zikazibuthe ezihlala njalo5.Eqinisweni, eminyakeni yamuva nje, mningi umsebenzi wokucwaninga owenziwe ekwenzeni izinto ezisekelwe ku-SFO ngokwezifiso ku-nanoscale ngokusebenzisa izinhlobonhlobo zokuhlanganisa nezindlela zokucubungula ukuze kuthuthukiswe usayizi, i-morphology, kanye nezakhiwo kazibuthe6,7,8.Ngaphezu kwalokho, ithole ukunakwa okukhulu ocwaningweni nasekuthuthukisweni kwezinhlelo zokuhlanganisa zokushintshisana9,10.I-magnetocrystalline anisotropy yayo ephezulu (K = 0.35 MJ/m3) eqondiswe eduze kwe-c-axis ye-hexagonal lattice yayo engu-11,12 ingumphumela oqondile wokuhlobana okuyinkimbinkimbi phakathi kwe-magnetism ne-crystal structure, i-crystallites nosayizi wokusanhlamvu, i-morphology kanye nokuthungwa.Ngakho-ke, ukulawula izici ezingenhla kuyisisekelo sokuhlangabezana nezidingo ezithile.Umfanekiso 1 ubonisa iqembu elivamile le-hexagonal space P63/mmc ye-SFO13, kanye nendiza ehambisana nokubonakaliswa kocwaningo lokuhlaziya iphrofayela yomugqa.
Phakathi kwezici ezihlobene zokunciphisa usayizi wezinhlayiyana ze-ferromagnetic, ukwakheka kwesizinda sesizinda esisodwa ngaphansi kwenani elibalulekile kuholela ekwandeni kwe-anisotropy kazibuthe (ngenxa yendawo ephakeme yendawo kuya kumthamo wevolumu), okuholela emkhakheni ophoqelelwe14,15.Indawo ebanzi engaphansi kobukhulu obubucayi (DC) ezintweni eziqinile (inani elivamile licishe libe ngu-1 µm), futhi lichazwa ngokuthi usayizi ohlangene (DCOH)16: lokhu kubhekisela endleleni yevolumu encane kakhulu yokususa uzibuthe kusayizi ohlangene. (DCOH) , Ivezwe njengevolumu yokuvula (VACT) 14. Kodwa-ke, njengoba kuboniswe ku-Figure 2, nakuba ubukhulu be-crystal buncane kune-DC, inqubo yokuguqula ingase ingahambisani.Ezingxenyeni ze-nanoparticle (NP), ivolumu ebalulekile yokuguqulwa incike ku-viscosity magnetic (S), futhi ukuxhomeka kwayo kwamagnetic field inikeza ulwazi olubalulekile mayelana nenqubo yokushintsha ye-NP magnetization17,18.
Ngenhla: Umdwebo weSchematic wokuvela kwenkambu ephoqelelwe enosayizi wezinhlayiyana, obonisa inqubo yokuhlehla yamagnetization ehambisanayo (ethathwe ku-15).I-SPS, i-SD, ne-MD imele isimo se-superparamagnetic, isizinda esisodwa, kanye nesizinda esiningi, ngokulandelana;I-DCOH ne-DC zisetshenziselwa ububanzi bokuhambisana kanye nobubanzi obubucayi, ngokulandelanayo.Ngezansi: Imidwebo yezinhlayiya ezinosayizi abahlukahlukene, ebonisa ukukhula kwamakristalu ukusuka kukristalu eyodwa ukuya ku-polycrystalline.futhikhombisa usayizi we-crystallite nosayizi wezinhlayiyana, ngokulandelana.
Kodwa-ke, ku-nanoscale, izici ezintsha eziyinkimbinkimbi nazo zethulwe, njengokuxhumana okunamandla kazibuthe phakathi kwezinhlayiya, ukusatshalaliswa kosayizi, ukuma kwezinhlayiyana, ukuphazamiseka kwendawo, kanye nokuqondiswa kwe-axis elula ye-magnetization, konke okwenza ukuhlaziywa kube inselele nakakhulu19, 20 .Lezi zakhi zithinta kakhulu ukusatshalaliswa kwesithiyo samandla futhi zifanelwe ukucatshangelwa ngokucophelela, ngaleyo ndlela zithinte imodi yokuhlehla yamagnetization.Ngalesi sisekelo, kubaluleke kakhulu ukuqonda kahle ukuhlobana phakathi kwevolumu kazibuthe kanye ne-nanostructured M-type hexaferrite SrFe12O19.Ngakho-ke, njengesistimu yemodeli, sasebenzisa isethi yama-SFO alungiselelwe indlela ye-sol-gel ephansi, futhi muva nje senze ucwaningo.Imiphumela yangaphambilini ibonisa ukuthi ubukhulu be-crystallites busezingeni le-nanometer, futhi, kanye nokuma kwe-crystallites, kuncike ekusetshenzisweni kokushisa okusetshenzisiwe.Ukwengeza, i-crystallinity yamasampuli anjalo incike endleleni yokuhlanganiswa, futhi ukuhlaziya okuningiliziwe kuyadingeka ukuze kucaciswe ubudlelwano phakathi kwama-crystallites nosayizi wezinhlayiyana.Ukuze kudalulwe lobu budlelwano, ngokuhlaziywa kwe-electron microscopy (TEM) yokudlulisela kuhlanganiswe nendlela ye-Rietveld kanye nokuhlaziywa kwephrofayili yomugqa wezibalo eziphezulu ze-X-ray powder diffraction, imingcele ye-crystal microstructure (okungukuthi, amakristalu nosayizi wezinhlayiyana, ukwakheka) kwahlaziywa ngokucophelela. .XRPD) imodi.Ukufakwa kwezinhlamvu zesakhiwo kuhloswe ukunquma izici ze-anisotropic zama-nanocrystallite atholiwe kanye nokufakazela ukuba nokwenzeka kokuhlaziywa kwephrofayela yomugqa njengendlela eqinile yokubonisa ukunwetshwa okuphezulu kububanzi be-nanoscale bezinto (i-ferrite).Kutholwe ukuthi ukusatshalaliswa kosayizi wekristalu onesisindo sevolumu G(L) kuncike kakhulu ekuqondeni kwecrystallographic.Kulo msebenzi, sibonisa ukuthi amasu okungezelela ayadingeka ngempela ukuze kukhishwe ngokunembile imingcele ehlobene nosayizi ukuchaza ngokunembile isakhiwo nezici kazibuthe zamasampuli anjalo empushana.Inqubo ye-reverse magnetization nayo yacwaningwa ukuze kucaciswe ubudlelwano phakathi kwezici zesakhiwo se-morphological nokuziphatha kazibuthe.
Ukuhlaziywa kwe-Rietveld kwedatha ye-X-ray powder diffraction (XRPD) ibonisa ukuthi usayizi wecrystallite eduze kwe-c-eksisi ungalungiswa ngokuphathwa kokushisa okufanele.Kubonisa ngokucacile ukuthi ukunwetshwa okuphezulu okubonwa kusampula yethu kungenzeka kungenxa yomumo we-anisotropic crystallite.Ukwengeza, ukuvumelana phakathi kobubanzi obumaphakathi obuhlaziywe ngu-Rietveld kanye nomdwebo we-Williamson-Hall (futhikuThebula S1) ikhombisa ukuthi amakristalu acishe awahluphi futhi akukho ukuguqulwa kwesakhiwo.Ukuvela kokusatshalaliswa kosayizi we-crystallite ngezindlela ezihlukene kugxilisa ukunaka kwethu kusayizi wezinhlayiyana ezitholiwe.Ukuhlaziywa akulula, ngoba isampula etholwe ukusha okuzenzakalelayo kwe-sol-gel yakhiwe ngama-agglomerates ezinhlayiya ezinesakhiwo esinezimbotshana6,9, amashumi amabili nanye.I-TEM isetshenziselwa ukufunda isakhiwo sangaphakathi sesampula yokuhlola kabanzi.Izithombe ezijwayelekile zenkundla ekhanyayo zibikwa kuMfanekiso 3a-c (ukuthola incazelo enemininingwane yokuhlaziywa, sicela ubheke isigaba 2 sezinto ezingeziwe).Isampula iqukethe izinhlayiya ezinokwakheka kwezingcezu ezincane.Ama-platelet ahlangana ndawonye ukuze akhe ama-aggregate anezimbobo ezinobukhulu obuhlukahlukene kanye nokuma.Ukuze ulinganisele ukusatshalaliswa kosayizi wamaplatelet, indawo yezinhlayiya eziyi-100 zesampula ngayinye ikalwe mathupha kusetshenziswa isofthiwe ye-ImageJ.Ububanzi besiyingi esilinganayo esinendawo yezinhlayiyana ezifanayo njengevelu kubalulwe usayizi omele wesiqephu ngasinye esilinganisiwe.Imiphumela yamasampula e-SFOA, SFOB kanye ne-SFOC ifinyezwa ku-Figure 3d-f, futhi nevelu yobubanzi obumaphakathi nayo iyabikwa.Ukwandisa izinga lokushisa lokucubungula kwandisa ubukhulu bezinhlayiya kanye nobubanzi bokusabalalisa.Kusukela ekuqhathaniseni phakathi kwe-VTEM ne-VXRD (Ithebula 1), kungabonakala ukuthi esimweni se-SFOA ne-SFOB amasampula, inani elilinganiselwe lama-crystallites nge-particle ngayinye libonisa imvelo ye-polycrystalline yalezi lamellae.Ngokuphambene, ivolumu yezinhlayiyana ze-SFOC iqhathaniswa nevolumu ye-crystallite evamile, okubonisa ukuthi iningi lama-lamellae angamakristalu awodwa.Siveza ukuthi osayizi ababonakalayo be-TEM kanye ne-X-ray diffraction bahlukile, ngoba ekugcineni, sikala ibhlokhi ehlakazekayo ehlangene (ingase ibe ncane kune-flake evamile): Ngaphezu kwalokho, umumo wephutha elincane lalokhu kuhlakazeka. izizinda zizobalwa ngokuhluka .
Izithombe ze-TEM zenkundla ekhanyayo ze-(a) SFOA, (b) SFOB kanye (c) ne-SFOC zibonisa ukuthi zenziwe ngezinhlayiya ezinomumo ofana nepuleti.Ukusabalalisa kosayizi okuhambisanayo kuboniswa ku-histogram yephaneli (df).
Njengoba sibonile futhi ekuhlaziyweni kwangaphambilini, ama-crystallite kusampula yempushana yangempela enza uhlelo lwe-polydisperse.Njengoba indlela ye-X-ray ibucayi kakhulu ekuhlakazeni okuhambisanayo, ukuhlaziywa okuphelele kwedatha ye-powder diffraction kuyadingeka ukuchaza ama-nanostructures amahle.Lapha, usayizi wamakristalu kuxoxwa ngawo ngokubonakala komsebenzi wokusabalalisa usayizi wekristallite onesisindo sevolumu engu-G(L)23, ongahunyushwa njengokushuba kwamathuba okuthola amakristalu okwakheka okucatshangwayo nosayizi, futhi isisindo sawo silingana yona.Ivolumu, kusampula ehlaziywe.Ngomumo we-crystallite we-prismatic, usayizi ojwayelekile we-crystallite onesisindo sevolumu (ubude obumaphakathi ohlangothini ku- [100], [110] kanye nezikhombisi-ndlela ze-[001]) zingabalwa.Ngakho-ke, sikhethe wonke amasampula amathathu e-SFO anamasayizi ahlukene ezinhlayiyana ngendlela yama-anisotropic flakes (bheka i-Reference 6) ukuze sihlole ukusebenza kahle kwale nqubo ukuze sithole ukusabalalisa usayizi we-crystallite onembile wezinto ze-nano-scale.Ukuze kuhlolwe i-anisotropic orientation ye-ferrite crystallites, ukuhlaziywa kwephrofayela yomugqa kwenziwa kudatha ye-XRPD yeziqongo ezikhethiwe.Amasampula e-SFO ahloliwe awazange aqukathe ukuhluka okufanelekile (okuhlanzekile) kwe-oda eliphezulu kusukela kusethi efanayo yezindiza zekristalu, ngakho-ke kwakungenakwenzeka ukuhlukanisa umnikelo wokwandisa umugqa kusukela kusayizi nokuhlanekezela.Ngesikhathi esifanayo, ukunwetshwa okubonwayo kwemigqa ye-diffraction kungenzeka kakhulu ngenxa yomphumela wesayizi, futhi umumo we-crystallite ojwayelekile uqinisekiswa ngokuhlaziywa kwemigqa eminingana.Umfanekiso 4 uqhathanisa umsebenzi wokusabalalisa usayizi wekristalu onesisindo sevolumu G(L) ngokuhambisana nesiqondisindlela esicacisiwe secrystallographic.Ifomu elijwayelekile lokusabalalisa usayizi we-crystallite ukusatshalaliswa kwe-lognormal.Isici esisodwa sakho konke ukusatshalaliswa kosayizi okutholiwe ukungafani kwazo.Ezimweni eziningi, lokhu kusatshalaliswa kungabangelwa inqubo ethile yokwakheka kwezinhlayiyana.Umehluko phakathi kwesilinganiso esibaliwe sikasayizi wenani eliphakeme elikhethiwe kanye nenani elikhishwe ekucwengisisweni kwe-Rietveld lingaphakathi kwebanga elamukelekayo (kucatshangelwa ukuthi izinqubo zokulinganisa izinsimbi zihlukile phakathi kwalezi zindlela) futhi liyafana naleyo evela kusethi ehambisanayo yezindiza I-Debye Usayizi ojwayelekile otholiwe uhambisana ne-equation ye-Scherrer, njengoba kuboniswe kuThebula 2. Umkhuba wesilinganiso se-crystallite sevolumu yezindlela ezimbili ezihlukene zokumodela sifana kakhulu, futhi ukuphambuka kosayizi ophelele kuncane kakhulu.Nakuba kungase kube nokungavumelani no-Rietveld, isibonelo, esimweni sokubonisa (110) kwe-SFOB, kungase kuhlobane nokunqunywa okulungile kwengemuva kuzo zombili izinhlangothi zokuboniswa okukhethiwe ebangeni elingu-1 degree 2θ endaweni ngayinye. isiqondiso.Noma kunjalo, isivumelwano esihle kakhulu phakathi kwalezi zindlela ezimbili zobuchwepheshe siqinisekisa ukubaluleka kwendlela.Kusukela ekuhlaziyweni kokunwetshwa kokuphakama okuphezulu, kusobala ukuthi usayizi ngokuhambisana [001] unokuncika okuthile endleleni yokuhlanganisa, okuholela ekwakhekeni kwamakristalu angenalutho ku-SFO6,21 ahlanganiswe yi-sol-gel.Lesi sici sivula indlela yokusetshenziswa kwale ndlela yokuklama ama-nanocrystals anomumo okhethwayo.Njengoba sonke sazi, isakhiwo sekristalu esiyinkimbinkimbi se-SFO (njengoba kukhonjisiwe kuMfanekiso 1) siwumongo wokuziphatha kwe-ferromagnetic ye-SFO12, ngakho-ke ukwakheka kanye nezici zosayizi zingalungiswa ukuze kuthuthukiswe ukwakheka kwesampula yezinhlelo zokusebenza (njengokuhlala unomphela. ahlobene uzibuthe).Siveza ukuthi ukuhlaziywa kosayizi we-crystallite kuyindlela enamandla yokuchaza i-anisotropy ye-crystallite shapes, futhi iqinisa nakakhulu imiphumela etholwe ngaphambilini.
(a) SFOA, (b) SFOB, (c) SFOC ekhethiwe reflection (100), (110), (004) volume weighted crystallite ukusatshalaliswa usayizi crystallite ukusatshalaliswa G(L).
Ukuze kuhlolwe ukuphumelela kwenqubo yokuthola usayizi oqondile we-crystallite ukusatshalaliswa kwezinto ze-nano-powder futhi uyisebenzise kuma-nanostructures ayinkimbinkimbi, njengoba kuboniswe ku-Figure 5, siqinisekisile ukuthi le ndlela iyasebenza ezintweni ze-nanocomposite (amanani ajwayelekile).Ukunemba kwecala lakhiwe nge-SrFe12O19/CoFe2O4 40/60 w/w %).Le miphumela ihambisana ngokugcwele nokuhlaziywa kwe-Rietveld (bheka amazwibela oMfanekiso 5 ukuze uqhathanise), futhi uma kuqhathaniswa nesistimu yesigaba esisodwa, ama-nanocrystals e-SFO angagqamisa i-morphology efana nepuleti.Le miphumela kulindeleke ukuthi isebenzise lokhu kuhlaziywa kwephrofayili yomugqa ezinhlelweni eziyinkimbinkimbi lapho izigaba eziningana zekristalu ezihlukene zingadlulela ngaphandle kokulahlekelwa ulwazi mayelana nezakhiwo zazo.
Ukusatshalaliswa kosayizi wecrystallite onesisindo sevolumu G(L) kokuboniswa okukhethiwe kwe-SFO ((100), (004)) ne-CFO (111) kuma-nanocomposites;uma kuqhathaniswa, amanani ahambisanayo okuhlaziya i-Rietveld angu-70(7), 45(6) kanye no-67(5) nm6.
Njengoba kuboniswe kuMfanekiso 2, ukunqunywa kobukhulu besizinda kazibuthe kanye nokulinganisa okulungile kwevolumu ebonakalayo kuyisisekelo sokuchaza izinhlelo ezinjalo eziyinkimbinkimbi kanye nokuqonda okucacile kokuxhumana nokuhleleka kwesakhiwo phakathi kwezinhlayiya kazibuthe.Muva nje, ukuziphatha kazibuthe kwamasampula e-SFO kuye kwafundwa ngokuningiliziwe, ngokunaka okukhethekile enqubweni yokuhlehla yamagnetization, ukuze kufundwe ingxenye engenakuhlehliswa ye-magnetic susceptibility (χirr) (Umfanekiso we-S3 uyisibonelo se-SFOC)6.Ukuze sithole ukuqonda okujulile kwendlela yokuhlehla kazibuthe kule nanosystem esekelwe ku-ferrite, senze isilinganiso sokuphumula kazibuthe endaweni engemuva (HREV) ngemva kokugcwaliswa kwesimo endaweni ethile.Cabangela \(M\left(t\right)\proptoSln\left(t\right)\) (bona Umfanekiso 6 kanye nokokusebenza okungeziwe ukuze uthole imininingwane eyengeziwe) bese uthola ivolumu yokuvula (VACT).Njengoba ingachazwa njengevolumu encane kakhulu yezinto ezingahle zihlehliswe ngokuhambisanayo kumcimbi, le pharamitha imele ivolomu “yozibuthe” ehilelekile enqubweni yokuhlehla.Inani lethu le-VACT (bona Ithebula S3) lihambisana nendilinga enobubanzi obucishe bube ngu-30 nm, echazwa ngokuthi i-diameter ehambisanayo (DCOH), echaza umkhawulo ongaphezulu wokuhlehla kozibuthe wesistimu ngokuzungezisa okuhambisanayo.Nakuba kunomehluko omkhulu kumthamo wezinhlayiya ezibonakalayo (i-SFOA inkulu ngokuphindwe ka-10 kune-SFOC), lawa manani ahlala njalo futhi mancane, okubonisa ukuthi umshini wokuguqula uzibuthe wazo zonke izinhlelo uhlala ufana (uhambisana nalokho esikufunayo. wuhlelo lwesizinda esisodwa) 24 .Ekugcineni, i-VACT inomthamo womzimba omncane kakhulu kunokuhlaziywa kwe-XRPD ne-TEM (i-VXRD ne-VTEM kuThebula S3).Ngakho-ke, singaphetha ngokuthi inqubo yokushintsha ayenzeki kuphela ngokuzungeza okuhambisanayo.Qaphela ukuthi imiphumela etholwe kusetshenziswa ama-magnetometer ahlukene (Umfanekiso S4) inikeza amanani afanayo e-DCOH.Mayelana nalokhu, kubaluleke kakhulu ukuchaza ububanzi obubalulekile bezinhlayiya zesizinda esisodwa (DC) ukuze kunqunywe inqubo yokuguqula enengqondo kakhulu.Ngokohlaziyo lwethu (bona okokusebenza okungeziwe), singaphetha ngokuthi i-VACT etholiwe ibandakanya indlela yokuzungezisa engahlangene, ngoba i-DC (~0.8 µm) ikude kakhulu ne-DC (~0.8 µm) yezinhlayiyana zethu, okungukuthi, ukwakheka kwezindonga zesizinda akukona Khona-ke wathola ukwesekwa okuqinile futhi wathola ukucushwa kwesizinda esisodwa.Lo mphumela ungachazwa ngokubunjwa kwesizinda sokusebenzisana25, 26. Sicabanga ukuthi i-crystallite eyodwa ibamba iqhaza esizindeni sokusebenzisana, esidlulela ezinhlayiyeni ezixhumene ngenxa ye-microstructure ehlukahlukene yalezi zinto27,28.Nakuba izindlela ze-X-ray zizwela kuphela i-microstructure emihle yezizinda (ama-microcrystals), izilinganiso zokuphumula kazibuthe zinikeza ubufakazi bezinto eziyinkimbinkimbi ezingase zenzeke kuma-SFO ane-nanostructured.Ngakho-ke, ngokuthuthukisa usayizi we-nanometer wezinhlamvu ze-SFO, kungenzeka ukuvimbela ukushintshela kunqubo yokuguqulwa kwesizinda esiningi, ngaleyo ndlela kugcinwe ukuphoqeleka okuphezulu kwalezi zinto.
(a) Ijika kazibuthe elincike esikhathini le-SFOC likalwa endaweni ehlukile ehlehlayo amanani e-HREV ngemva kokugcwaliswa kwesikhala ku-5 T no-300 K (okuboniswe eduze kwedatha yokuhlola) (i-magnetization ijwayele ukuhambisana nesisindo sesampula);ukuze kucace, Isethi ibonisa idatha yokuhlola yenkambu engu-0.65 T (umbuthano omnyama), onokulingana okungcono kakhulu (umugqa obomvu) (i-magnetization ijwayele inani lokuqala M0 = M(t0));(b) i-viscosity kazibuthe ehambisanayo (S) iwukuphambana kwe-SFOC A umsebenzi wenkundla (umugqa uwumhlahlandlela weso);(c) uhlelo lokuvula olunemininingwane yesikali sobude obuphathekayo/sizibuthe.
Ngokuvamile, ukuhlehliswa kazibuthe kungase kwenzeke ngochungechunge lwezinqubo zasendaweni, ezifana ne-nucleation yodonga lwesizinda, ukusabalalisa, ukuphina nokungaphina.Endabeni yezinhlayiya zesizinda esisodwa se-ferrite, indlela yokwenza kusebenze i-nucleation-mediated futhi ibangelwa ukuguqulwa kwamandla kazibuthe okuncane kunomthamo wokuhlehla kazibuthe jikelele (njengoba kuboniswe kuMfanekiso 6c) 29.
Igebe eliphakathi kukazibuthe obalulekile kanye nobubanzi bomzimba lisikisela ukuthi imodi engahambisani isenzakalo esihambisanayo sokuhlehla kwesizinda kazibuthe, okungenzeka kube ngenxa yokungahlangani kwezinto ezibonakalayo nokungalingani kwendawo, okuba kuhlotshaniswe lapho usayizi wezinhlayiya ukhuphuka ngo-25, okuholela ekuphambukeni isimo samagnetization esifanayo.
Ngakho-ke, singaphetha ngokuthi kulolu hlelo, inqubo yokuguqula i-magnetization iyinkimbinkimbi kakhulu, futhi imizamo yokunciphisa usayizi esikalini se-nanometer idlala indima ebalulekile ekusebenzelaneni phakathi kwe-microstructure ye-ferrite kanye ne-magnetism..
Ukuqonda ubudlelwano obuyinkimbinkimbi phakathi kwesakhiwo, ifomu kanye ne-magnetism kuyisisekelo sokuklama nokuthuthukisa izinhlelo zokusebenza zesikhathi esizayo.Ukuhlaziywa kwephrofayili yomugqa yephethini ekhethiwe ye-XRPD ye-SrFe12O19 kuqinisekise umumo we-anisotropic wama-nanocrystals atholwe ngendlela yethu yokuhlanganisa.Kuhlanganiswe nokuhlaziywa kwe-TEM, imvelo ye-polycrystalline yale zinhlayiya yafakazelwa, futhi kamuva yaqinisekiswa ukuthi ubukhulu be-SFO obuhloliwe kulo msebenzi buphansi kunobubanzi obubalulekile besizinda esisodwa, naphezu kobufakazi bokukhula kwe-crystallite.Ngalesi sisekelo, siphakamisa inqubo ye-magnetization engenakuhlehliswa esekelwe ekwakhekeni kwesizinda sokusebenzisana esakhiwe amakristalu axhumene.Imiphumela yethu ifakazela ukuhlobana okuseduze phakathi kwe-particle morphology, ukwakheka kwekristalu nosayizi wecrystallite okukhona ezingeni le-nanometer.Lolu cwaningo luhlose ukucacisa inqubo yokwenza kazibuthe ehlehlayo yezinto eziqinile zikazibuthe futhi inqume indima yezimpawu ze-microstructure ekuziphatheni okuwumphumela kazibuthe.
Amasampuli ahlanganiswa kusetshenziswa i-citric acid njenge-chelating agent/fuel ngokwendlela yokushiswa okuzenzakalelayo kwe-sol-gel, ebikwe ku-Reference 6. Izimo zokuhlanganiswa zathuthukiswa ukuze kutholwe osayizi abathathu abahlukene bamasampuli (SFOA, SFOB, SFOC), ababe etholwe ngokwelashwa okufanele kwe-annealing emazingeni okushisa ahlukene (1000, 900, no-800°C, ngokulandelana).Ithebula elithi S1 lifingqa izici kazibuthe futhi lithola ukuthi ziyafana.I-nanocomposite SrFe12O19/CoFe2O4 40/60 w/w% nayo yalungiswa ngendlela efanayo.
Iphethini ye-diffraction ikalwe kusetshenziswa imisebe ye-CuKα (λ = 1.5418 Å) ku-Bruker D8 powder diffractometer, futhi ububanzi bokuhlukaniswa komtshina bubekwe ku-0.2 mm.Sebenzisa ikhawunta ye-VANTEC ukuze uqoqe idatha ebangeni elingu-2θ elingu-10-140°.Izinga lokushisa ngesikhathi sokuqoshwa kwedatha ligcinwe ku-23 ± 1 °C.Ukuboniswa kukalwa ngobuchwepheshe besinyathelo nokuskena, futhi ubude besinyathelo sawo wonke amasampula okuhlola bungu-0.013° (2theta);inani eliphakeme eliphakeme lebanga lokulinganisa ngu-2.5 kanye + 2.5° (2theta).Esiqongweni ngasinye, kubalwa inani lama-quanta angu-106, kanti emsileni kukhona cishe ama-quanta angu-3000.Iziqongo ezimbalwa zokuhlola (ezihlukanisiwe noma ezigqagqene kancane) zikhethelwe ukuhlaziya okwengeziwe ngesikhathi esisodwa: (100), (110) kanye (004), ezenzeke nge-engeli ye-Bragg eduze kwe-engeli ye-Bragg yomugqa wokubhalisa we-SFO.Ukuqina kokuhlola kwalungiselelwa isici se-Lorentz polarization, futhi ingemuva lasuswa ngoshintsho lomugqa ocatshangwayo.I-NIST standard LaB6 (NIST 660b) yasetshenziswa ukuze kulinganiswe insimbi nokunwetshwa kwe-spectral.Sebenzisa indlela ye-LWL (Louer-Weigel-Louboutin) yokuguqula indlela engu-30,31 ukuze uthole imigqa emsulwa yokuhlukanisa.Le ndlela isetshenziswa ohlelweni lokuhlaziya iphrofayili PROFIT-software32.Kusukela ekufakweni kwedatha yokuqina okulinganiselwe kwesampula kanye nezinga elinomsebenzi mbumbulu we-Voigt, umugqa ohambisanayo wekhontuyutha f(x) uyakhishwa.Umsebenzi wokusabalalisa usayizi G(L) unqunywa ku-f(x) ngokulandela inqubo eyethulwe ku-Reference 23. Ukuze uthole imininingwane eyengeziwe, sicela ubheke okokusebenza okungeziwe.Njengesengezo ekuhlaziyweni kwephrofayili yomugqa, uhlelo lwe-FULLPROF lusetshenziselwa ukwenza ukuhlaziya kwe-Rietveld kudatha ye-XRPD (imininingwane ingatholakala ku-Maltoni et al. 6).Ngamafuphi, kumodeli ye-Rietveld, iziqongo zokuphazamiseka zichazwa umsebenzi oguquliwe we-Thompson-Cox-Hastings mbumbulu we-Voigt.Ukuthuthukiswa kwe-LeBail kwedatha kwenziwe ngezinga le-NIST LaB6 660b ukuze kuboniswe umnikelo wethuluzi ekwandiseni inani eliphakeme kakhulu.Ngokuya nge-FWHM ebaliwe (ububanzi obugcwele kuhhafu wobukhulu obuphakeme), isibalo se-Debye-Scherrer singasetshenziswa ukubala usayizi omaphakathi onesisindo sevolumu wesizinda esihlangene sekristalu ehlakazekayo:
Lapho u-λ eyi-X-ray radiation wavelength, u-K uyisici somumo (0.8-1.2, ngokuvamile esilingana no-0.9), futhi u-θ uyi-engeli ye-Bragg.Lokhu kusebenza: ukuboniswa okukhethiwe, isethi ehambisanayo yezindiza kanye nephethini yonke (10-90 °).
Ngaphezu kwalokho, isibonakhulu se-Philips CM200 esisebenza ku-200 kV futhi esifakwe umcu we-LaB6 sasetshenziselwa ukuhlaziya i-TEM ukuze kutholwe ulwazi mayelana ne-particle morphology kanye nokusabalalisa usayizi.
Isilinganiso sokuphumuza kazibuthe senziwa amathuluzi amabili ahlukene: I-Physical Property Measurement System (PPMS) kusukela ku-Quantum Design-Vibrating Sample Magnetometer (VSM), ifakwe uzibuthe oyi-9 T superconducting, kanye ne-MicroSense Model 10 VSM enozibuthe kagesi.Inkambu ingu-2 T, isampula igcwele ensimini (μ0HMAX:-5 T no-2 T, ngokulandelanayo ensimbini ngayinye), bese kusetshenziswa inkambu ehlehlayo (HREV) ukuletha isampula endaweni yokushintsha (eduze ne-HC ), bese ukubola kwamagnetization kuqoshwa njengomsebenzi wesikhathi esingaphezu kwemizuzu engama-60.Isilinganiso senziwa ku-300 K. Ivolumu yokuvula ehambisanayo iyahlolwa ngokusekelwe kulawo manani akalwayo achazwe kokokusebenza okungeziwe.
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