litaba

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Thepa ea makenete ea SrFe12O19 (SFO) e thata ea hexaferrite e laoloa ke kamano e rarahaneng ea microstructure ea eona, e khethollang bohlokoa ba eona ho ts'ebetso ea magnete e sa feleng.Khetha sehlopha sa SFO nanoparticles fumanoa ka sol-gel spontaneous combustion synthesis, le ho etsa ka botebo sebopeho X-ray phofo diffraction (XRPD) tlhaku ka G (L) line profile analysis.Kabo ea boholo ba kristallite e fumanoeng e senola ho itšetleha ho totobetseng ha boholo ho latela tataiso ea [001] ka mokhoa oa ho kopanya, o lebisang ho thehoeng ha likristale tse fokolang.Ho phaella moo, boholo ba SFO nanoparticles bo ile ba khethoa ke tlhahlobo ea transmission electron microscopy (TEM), 'me palo e tloaelehileng ea likristale ka likaroloana e hakanngoa.Liphetho tsena li hlahlobiloe ho bontša sebopeho sa sebaka se le seng ka tlase ho boleng ba bohlokoa, 'me molumo oa ts'ebetso o tsoa ho litekanyo tsa matla a khoheli tse itšetlehileng ka nako, tse reretsoeng ho hlakisa ts'ebetso ea reverse magnetization ea lisebelisoa tse thata tsa makenete.
Lisebelisoa tsa makenete tsa Nano-scale li na le bohlokoa bo boholo ba saense le thekenoloji, hobane thepa ea bona ea makenete e bonts'a boitšoaro bo fapaneng haholo ha bo bapisoa le boholo ba bona ba molumo, e leng se tlisang maikutlo le lits'ebetso tse ncha1,2,3,4.Har'a lisebelisoa tse nang le nanostructured, M-mofuta oa hexaferrite SrFe12O19 (SFO) e fetohile mokhethoa ea khahlehang bakeng sa lits'ebetso tsa magnete tse sa feleng5.Ebile, lilemong tsa morao tjena, ho entsoe mosebetsi o mongata oa ho etsa lipatlisiso mabapi le ho etsa lisebelisoa tse thehiloeng ho SFO ho nanoscale ka mekhoa e fapaneng ea ho kopanya le ho e lokisa ho ntlafatsa boholo, morphology le thepa ea makenete6,7,8.Ho feta moo, e fumane tlhokomelo e kholo lipatlisisong le nts'etsopele ea mekhoa ea ho kopanya phapanyetsano9,10.Anisotropy ea eona e phahameng ea magnetocrystalline (K = 0.35 MJ / m3) e shebaneng le c-axis ea hexagonal lattice 11,12 ke phello e tobileng ea kamano e rarahaneng pakeng tsa magnetism le sebopeho sa kristale, crystallites le boholo ba lijo-thollo, morphology le sebopeho .Ka hona, ho laola litšobotsi tse ka holimo ke motheo oa ho finyella litlhoko tse khethehileng.Setšoantšo sa 1 se bonts'a sehlopha se tloaelehileng sa sebaka sa hexagonal P63 / mmc sa SFO13, le sefofane se lumellanang le pontšo ea thuto ea ho hlahloba boemo ba line.
Har'a litšoaneleho tse amanang le ho fokotsa boholo ba likaroloana tsa ferromagnetic, ho thehoa ha sebaka se le seng sa marang-rang se ka tlaase ho bohlokoa ba bohlokoa ho lebisa ho eketseha ha magnetic anisotropy (ka lebaka la sebaka se phahameng ho ea ho tekanyo ea molumo), e leng se lebisang tšimong e qobelloang14,15.Sebaka se pharaletseng se ka tlase ho tekanyo ea bohlokoa (DC) ka thepa e thata (boleng bo tloaelehileng bo ka bang 1 µm), 'me bo hlalosoa ke boholo bo bitsoang coherent size (DCOH)16: sena se bolela mokhoa o monyenyane ka ho fetisisa oa molumo oa demagnetization ka boholo bo kopanetsoeng. (DCOH) , E hlalositsoe e le molumo oa ts'ebetso (VACT) 14. Leha ho le joalo, joalokaha ho bontšitsoe Setšoantšong sa 2, le hoja boholo ba kristale bo le nyane ho feta DC, mokhoa oa ho fetola o ka 'na oa se ke oa lumellana.Likarolong tsa nanoparticle (NP), molumo o boima oa ho fetoha o itšetlehile ka viscosity ea magnetic (S), 'me ho itšetleha ha matla a khoheli ho fana ka tlhahisoleseding ea bohlokoa mabapi le mokhoa oa ho fetola NP magnetization17,18.
Ka holimo: Sets'oants'o sa moralo oa phetoho ea tšimo e qobelloang ka boholo ba likaroloana, e bonts'ang ts'ebetso ea phetoho ea magnetization e lumellanang (e fetisitsoeng ho 15).SPS, SD, le MD li emetse boemo ba superparamagnetic, domain e le 'ngoe, le li-multidomain, ka ho latellana;DCOH le DC li sebelisetsoa bophara bo kopanetsoeng le bophara bo tebileng, ka ho latellana.Ka tlase: Lits'oants'o tsa likaroloana tsa boholo bo fapaneng, tse bonts'ang kholo ea likristale ho tloha kristale e le 'ngoe ho ea ho polycrystalline.lebonts'a boholo ba crystallite le karoloana, ka ho latellana.
Leha ho le joalo, ho nanoscale, ho boetse ho hlahisitsoe likarolo tse ncha tse rarahaneng, tse kang ho sebelisana ho matla ha matla a khoheli pakeng tsa likaroloana, kabo ea boholo, sebōpeho sa likaroloana, bothata ba holim'a metsi, le tataiso ea axis e bonolo ea magnetization, tseo kaofela li etsang hore tlhahlobo e be thata haholoanyane19, 20 .Lintho tsena li ama kabo ea mokoallo oa matla haholo 'me li lokeloa ke ho nahanoa ka hloko, ka hona li ama mokhoa oa ho khutlisa magnetization.Motheong ona, ho bohlokoa haholo ho utloisisa ka nepo kamano pakeng tsa molumo oa makenete le mofuta oa M-mofuta oa hexaferrite SrFe12O19 o hlophisitsoeng hantle.Ka hona, joalo ka mokhoa oa mohlala, re sebelisitse sete sa li-SFO tse lokiselitsoeng ke mokhoa o ka tlase-holimo oa sol-gel, mme re sa tsoa etsa lipatlisiso.Liphello tse fetileng li bontša hore boholo ba li-crystallites bo sebakeng sa nanometer, 'me eona, hammoho le sebōpeho sa li-crystallites, ho itšetlehile ka phekolo ea mocheso e sebelisoang.Ho phaella moo, crystallinity ea lisampole tse joalo e itšetlehile ka mokhoa oa ho kopanya, 'me ho hlokahala tlhahlobo e qaqileng haholoanyane ho hlakisa kamano pakeng tsa crystallites le boholo ba likaroloana.E le ho senola kamano ena, ka tlhahlobo ea transmission electron microscopy (TEM) e kopantsoeng le mokhoa oa Rietveld le tlhahlobo ea profil ea line ea lipalo-palo tse phahameng tsa X-ray powder diffraction, litekanyetso tsa kristale microstructure (ke hore, likristale le boholo ba karoloana, sebōpeho) li ile tsa hlahlojoa ka hloko. .XRPD) mokhoa.Sebopeho sa sebopeho se ikemiselitse ho fumana litšoaneleho tsa anisotropic tsa li-nanocrystallite tse fumanoeng le ho paka ho khonahala ha tlhahlobo ea profil ea line e le mokhoa o matla oa ho bonts'a katoloso ea tlhoro ho nanoscale range of (ferrite) lisebelisoa.Ho fumanoe hore kabo ea boholo ba kristallite e boima ba bophahamo ba molumo G (L) e itšetlehile haholo ka tataiso ea crystallographic.Mosebetsing ona, re bonts'a hore mekhoa ea tlatsetso e hlile e hlokahala ho ntša ka nepo li-parameter tse amanang le boholo ho hlalosa ka nepo sebopeho le litšobotsi tsa khoheli tsa lisampole tse joalo tsa phofo.Ts'ebetso ea reverse magnetization e ile ea boela ea ithutoa ho hlakisa kamano pakeng tsa litšobotsi tsa sebopeho sa morphological le boitšoaro ba khoheli.
Tlhahlobo ea Rietveld ea lintlha tsa X-ray powder diffraction (XRPD) e bontša hore boholo ba crystallite haufi le c-axis bo ka fetoloa ka phekolo e loketseng ea mocheso.E bontša ka ho hlaka hore keketseho ea tlhoro e bonoang sampoleng ea rona e kanna ea ba ka lebaka la sebopeho sa anisotropic crystallite.Ho phaella moo, ho lumellana pakeng tsa bophara bo tloaelehileng bo hlahlobiloeng ke Rietveld le setšoantšo sa Williamson-Hall (leho Lethathamo la S1) e bonts'a hore likristale li batla li se na mathata 'me ha ho na deformation ea sebopeho.Phetoho ea kabo ea boholo ba crystallite ka litsela tse fapaneng e lebisa tlhokomelo ea rona ho boholo ba likaroloana tse fumanoeng.Tlhahlobo ha e bonolo, hobane sampole e fumanoeng ka ho tuka ha sol-gel ka boithaopo e entsoe ka li-agglomerate tsa likaroloana tse nang le sebopeho sa porous6,9, mashome a mabeli a motso o mong.TEM e sebelisoa ho ithuta sebopeho sa kahare sa sampole ea liteko ka botlalo.Litšoantšo tse tloaelehileng tse khanyang li tlalehoa ho Setšoantšo sa 3a-c (bakeng sa tlhaloso e qaqileng ea tlhahlobo, ka kopo sheba karolo ea 2 ea lisebelisoa tsa tlatsetso).Mohlala o na le likaroloana tse nang le sebōpeho sa likotoana tse nyenyane.Li-platelet li kopana ho etsa li-aggregate tse nang le masoba tsa boholo le libopeho tse fapaneng.Bakeng sa ho hakanya kabo ea boholo ba liplatelete, sebaka sa likaroloana tse 100 tsa sampole ka 'ngoe se ne se lekantsoe ka letsoho ho sebelisoa software ea ImageJ.Bophara ba selikalikoe se lekanang se nang le sebaka se lekanang le sa bohlokoa se amahanngoa le boholo ba moemeli oa karolo ka 'ngoe e lekantsoeng.Liphetho tsa lisampole tsa SFOA, SFOB le SFOC li akaretsoa ka Sets'oants'o sa 3d-f, 'me boleng bo tloaelehileng ba bophara bo boetse bo tlalehoa.Ho eketsa mocheso oa ho sebetsa ho eketsa boholo ba likaroloana le bophara ba bona ba ho aba.Ho tloha papisong pakeng tsa VTEM le VXRD (Letlapa la 1), ho ka bonoa hore tabeng ea mehlala ea SFOA le SFOB, palo e tloaelehileng ea li-crystallites ka karoloana e bontša mofuta oa polycrystalline oa li-lamellae tsena.Ka lehlakoreng le leng, palo ea likaroloana tsa SFOC e bapisoa le palo e tloaelehileng ea crystallite, e bontšang hore boholo ba lamellae ke likristale tse le 'ngoe.Re bontša hore boholo bo bonahalang ba TEM le X-ray diffraction bo fapane, hobane qetellong, re lekanya sebaka se tsitsitseng sa ho hasana (e ka 'na ea e-ba nyenyane ho feta flake e tloaelehileng): Ho phaella moo, mokhoa o fokolang oa phoso ea ho hasana tsena. libaka li tla baloa ka diffraction .
Litšoantšo tsa TEM tse khanyang tsa (a) SFOA, (b) SFOB le (c) SFOC li bonts'a hore li entsoe ka likaroloana tse nang le sebopeho se kang poleiti.Kabo ea boholo bo lekanang e bonts'oa ho histogram ea phanele (df).
Joalokaha re boetse re hlokometse tlhahlobisong e fetileng, li-crystallites ka sampuli ea phofo ea sebele li theha tsamaiso ea polydisperse.Kaha mokhoa oa X-ray o na le kutloelo-bohloko haholo ho thibela ho qhalakanngoa ho tsitsitseng, ho hlahlojoa ka botlalo ha data ea phofshoana ea phofo e hlokahalang ho hlalosa li-nanostructures tse ntle.Mona, boholo ba likristale bo buisanoa ka sebopeho sa ts'ebetso ea kabo ea boholo ba kristallite e boima ba molumo G(L)23, e ka hlalosoang e le sekhahla sa monyetla oa ho fumana likristale tsa sebopeho le boholo bo nahanoang, 'me boima ba eona bo lekana le eona.Bolumo, ka mohlala o hlahlobiloeng.Ka sebopeho sa prismatic crystallite, boholo ba kristallite bo boima ba molumo (bolelele ba lehlakoreng le leng ka [100], [110] le [001] directions) bo ka baloa.Ka hona, re khethile mehlala eohle e meraro ea SFO e nang le boholo bo fapaneng ba likaroloana ka mokhoa oa li-anisotropic flakes (bona Reference 6) ho hlahloba katleho ea mokhoa ona ho fumana kabo e nepahetseng ea boholo ba crystallite ea lisebelisoa tsa nano-scale.E le ho hlahloba mokhoa oa anisotropic oa li-crystallites tsa ferrite, ho hlahlojoa ha linepe ho ile ha etsoa ho data ea XRPD ea litlhōrō tse khethiloeng.Mehlala ea SFO e lekiloeng e ne e se na phapang e bonolo (e hloekileng) e phahameng ho tloha sehlopheng se tšoanang sa lifofane tsa kristale, kahoo ho ne ho sa khonehe ho arola monehelo oa ho atolosa moeli ho tloha boholo le ho sotha.Ka nako e ts'oanang, ho atolosoa ha melapo ea diffraction ho ka etsahala haholo ka lebaka la phello ea boholo, 'me sebopeho se tloaelehileng sa crystallite se netefatsoa ka ho hlahlojoa ha mela e mengata.Setšoantšo sa 4 se bapisa ts'ebetso ea kabo ea boholo ba kristale e boima ba molumo G(L) ho latela tataiso e hlalositsoeng ea crystallographic.Mofuta o tloaelehileng oa kabo ea boholo ba crystallite ke kabo e tloaelehileng.Tšobotsi e 'ngoe ea likarolo tsohle tsa boholo bo fumanoeng ke ho se lumellane ha tsona.Maemong a mangata, kabo ena e ka amahanngoa le mokhoa o itseng o hlalosoang oa sebopeho sa likaroloana.Phapang lipakeng tsa boholo bo lekantsoeng ba palohare ea tlhoro e khethiloeng le boleng bo ntšitsoeng ho ntlafatso ea Rietveld e ka har'a mefuta e amohelehang (ho nahanoa hore mekhoa ea ho lekanya lisebelisoa e fapane pakeng tsa mekhoa ena) 'me e tšoana le e tsoang ho sehlopha se lumellanang sa lifofane Debye Karolelano ea boholo bo fumanoeng bo lumellana le equation ea Scherrer, joalokaha ho bontšitsoe Lethathamong la 2. Tloaelo ea boholo ba boholo ba crystallite ea boholo ba mekhoa e 'meli e fapaneng ea ho etsa mohlala e tšoana haholo,' me ho kheloha ha boholo bo feletseng ho nyenyane haholo.Leha ho ka ba le ho se dumellane le Rietveld, ho etsa mohlala, tabeng ya (110) ponahatso ya SFOB, e ka nna ya amana le maikemisetso a nepahetseng a bokamorao mahlakoreng a mabedi a ponahatso e kgethilweng bohole ba 1 degree 2θ sebakeng se seng le se seng. tataiso.Leha ho le joalo, tumellano e babatsehang pakeng tsa mekhoa e 'meli ea theknoloji e tiisa bohlokoa ba mokhoa ona.Ho latela tlhahlobo ea ho atolosoa ha tlhōrō, ho hlakile hore boholo bo tsamaeang [001] bo itšetlehile ka mokhoa o itseng oa mokhoa oa ho kopanya, ho fella ka ho thehoa ha likristale tse fokolang ho SFO6,21 tse entsoeng ke sol-gel.Tšobotsi ena e bula tsela ea tšebeliso ea mokhoa ona ho rala li-nanocrystals tse nang le libopeho tse khethehileng.Joalo ka ha bohle re tseba, sebopeho se rarahaneng sa kristale ea SFO (joalo ka ha ho bonts'itsoe ho Setšoantšo sa 1) ke motheo oa boitšoaro ba ferromagnetic ba SFO12, kahoo sebopeho le boholo ba litšoaneleho li ka fetoloa ho ntlafatsa moralo oa sampole bakeng sa lits'ebetso (tse joalo ka ka ho sa feleng. tse amanang le makenete).Re bontša hore tlhahlobo ea boholo ba crystallite ke mokhoa o matla oa ho hlalosa anisotropy ea libopeho tsa crystallite, 'me e matlafatsa le ho feta liphello tse fumanoeng pele.
(a) SFOA, (b) SFOB, (c) SFOC e khethiloeng e bonahatsa (100), (110), (004) kabo ea boholo ba crystallite ea boima ba kristale G(L).
E le ho hlahloba katleho ea ts'ebetso ea ho fumana boholo bo nepahetseng ba boholo ba crystallite kabo ea lisebelisoa tsa nano-powder le ho e sebelisa ho li-nanostructures tse rarahaneng, joalokaha ho bontšitsoe setšoantšong sa 5, re netefalitse hore mokhoa ona o sebetsa ka thepa ea nanocomposite (litekanyetso tsa lebitso).Ho nepahala ha nyeoe ho entsoe ka SrFe12O19/CoFe2O4 40/60 w/w %).Liphetho tsena li lumellana ka botlalo le tlhahlobo ea Rietveld (bona tlhaloso ea Setšoantšo sa 5 bakeng sa papiso), 'me ha e bapisoa le tsamaiso ea karolo e le' ngoe, SFO nanocrystals e ka totobatsa morphology e kang poleiti.Liphetho tsena li lebelletsoe ho sebelisa tlhahlobo ea profil ea line ho litsamaiso tse rarahaneng haholo moo mekhahlelo e mengata e fapaneng ea kristale e ka kopanang ntle le ho lahleheloa ke tlhahisoleseling mabapi le meaho ea bona.
Kabo ea boholo ba kristallite e boima ba molumo G (L) ea lipontšo tse khethiloeng tsa SFO ((100), (004)) le CFO (111) ka nanocomposites;papisong, litekanyetso tse lumellanang tsa tlhahlobo ea Rietveld ke 70 (7), 45 (6) le 67 (5) nm6.
Joalokaha ho bontšitsoe setšoantšong sa 2, boikemisetso ba boholo ba matla a khoheli le tekanyo e nepahetseng ea molumo oa 'mele ke motheo oa ho hlalosa mekhoa e joalo e rarahaneng le ho utloisisa ka ho hlaka tšebelisano le tlhophiso ea sebopeho pakeng tsa likaroloana tsa magnetic.Haufinyane tjena, boits'oaro ba makenete ba lisampole tsa SFO bo ithutoa ka botlalo, ka tlhokomelo e khethehileng ts'ebetsong ea ho khutlisa matla a khoheli, e le ho ithuta karolo e ke keng ea fetoloa ea ts'oaetso ea makenete (χirr) (Setšoantšo sa S3 ke mohlala oa SFOC)6.E le hore re fumane kutloisiso e tebileng ea mochine oa ho fetola magnetization ho nanosystem ena e thehiloeng ho ferrite, re ile ra etsa tekanyo ea ho phomola ha makenete sebakeng se ka morao (HREV) ka mor'a ho tlala ka tsela e fanoeng.Nahana ka \(M\left(t\right)\proptoSln\left(t\right)\) (sheba Figure 6 le thepa ea tlatsetso bakeng sa lintlha tse ling) ebe u fumana molumo oa ho kenya tšebetsong (VACT).Kaha e ka hlalosoa e le palo e nyane ka ho fetisisa ea lintho tse ka fetoloang ka mokhoa o ts'oanang ketsahalong, paramethara ena e emela molumo oa "magnetic" o amehang ts'ebetsong ea ho khutlisa.Boleng ba rona ba VACT (bona Lethathamo la S3) le lumellana le pherekano e bophara ba hoo e ka bang 30 nm, e hlalosoang e le bophara bo kopanetsoeng (DCOH), e hlalosang moeli o ka holimo oa phetoho ea magnetization ea tsamaiso ka ho potoloha ho hokahaneng.Le hoja ho na le phapang e kholo ho palo ea 'mele ea likaroloana (SFOA e kholo ka makhetlo a 10 ho feta SFOC), litekanyetso tsena li lula li le teng ebile li nyenyane, ho bontša hore mochine oa ho fetola matla oa magnetization oa litsamaiso tsohle o ntse o tšoana (o lumellana le seo re se batlang. is the single domain system) 24 .Qetellong, VACT e na le molumo o monyenyane haholo oa 'mele ho feta XRPD le tlhahlobo ea TEM (VXRD le VTEM ho Lethathamo la S3).Ka hona, re ka fihlela qeto ea hore mokhoa oa ho fetola ha o etsahale feela ka ho potoloha ho lumellanang.Hlokomela hore liphetho tse fumanoeng ka ho sebelisa li-magnetometer tse fapaneng (setšoantšo sa S4) li fana ka litekanyetso tse tšoanang tsa DCOH.Tabeng ena, ke habohlokoa haholo ho hlalosa bophara ba bohlokoa ba sebaka se le seng sa domain (DC) e le ho fumana mokhoa o nepahetseng ka ho fetisisa oa ho khutlisa.Ho latela tlhahlobo ea rona (sheba litaba tsa tlatsetso), re ka etsa qeto ea hore VACT e fumanoeng e kenyelletsa mokhoa o sa tsitsang oa ho potoloha, hobane DC (~0.8 µm) e hole haholo le DC (~0.8 µm) ea likaroloana tsa rona, ke hore, sebopeho sa marako a domain ha se Ebe o ile a fumana tšehetso e matla mme a fumana tlhophiso e le 'ngoe ea domain.Sephetho sena se ka hlalosoa ka ho thehoa ha sebaka sa ho sebelisana25, 26. Re nka hore crystallite e le 'ngoe e kopanela sebakeng sa ho sebelisana, se fetelang ho likaroloana tse hokahaneng ka lebaka la microstructure e fapaneng ea lisebelisoa tsena27,28.Le hoja mekhoa ea X-ray e ameha feela ho microstructure e ntle ea libaka (microcrystals), litekanyo tsa ho phomola ha makenete li fana ka bopaki ba liketsahalo tse rarahaneng tse ka 'nang tsa etsahala ho li-SFO tse nang le nanostructured.Ka hona, ka ho ntlafatsa boholo ba nanometer ea lijo-thollo tsa SFO, hoa khoneha ho thibela ho fetela ts'ebetsong ea ho fetola li-domain tse ngata, ka hona ho boloka ts'ebetso e phahameng ea lisebelisoa tsena.
(a) Mokokotlo o itšetlehileng ka nako oa magnetization oa SFOC o lekantsoe libakeng tse fapaneng tsa HREV ka morao ho 5 T le 300 K (e bontšitsoeng haufi le data ea liteko) (magnetization e tloaelehile ho latela boima ba sampuli);bakeng sa ho hlaka, Inset e bonts'a lintlha tsa liteko tsa tšimo ea 0,65 T (selika-likoe se setšo), se nang le mokhoa o motle ka ho fetisisa (mohala o mofubelu) (magnetization e tloaelehile ho boleng ba pele M0 = M (t0));(b) matla a khoheli a khoheli (S) ke mokhoa o fapaneng oa SFOC A ts'ebetso ea tšimo (mohala ke tataiso bakeng sa leihlo);(c) leano la ho kenya tšebetsong le nang le lintlha tsa sekala sa bolelele ba 'mele / makenete.
Ka kakaretso, phetoho ea magnetization e ka etsahala ka letoto la lits'ebetso tsa lehae, joalo ka nucleation ea lebota la domain, propagation, le pinning le unpinning.Tabeng ea likaroloana tsa ferrite tsa domain e le 'ngoe, mochine oa ts'ebetso ke nucleation-mediated' me o bakoa ke phetoho ea magnetization e nyenyane ho feta tekanyo ea kakaretso ea phetoho ea makenete (joalokaha ho bontšitsoe setšoantšong sa 6c) 29.
Phapang pakeng tsa magnetism e mahlonoko le bophara ba 'mele e fana ka maikutlo a hore mokhoa o sa lumellaneng ke ketsahalo e ts'oanang ea phetoho ea matla a khoheli, e ka' nang ea bakoa ke inhomogeneities ea lintho tse bonahalang le ho se lekane ha bokaholimo, tse amanang ha boholo ba karoloana bo eketseha ka 25, bo bakang ho kheloha boemo bo ts'oanang ba magnetization.
Ka hona, re ka etsa qeto ea hore tsamaisong ena, ts'ebetso ea ho fetola magnetization e rarahane haholo, 'me boiteko ba ho fokotsa boholo ba tekanyo ea nanometer bo phetha karolo ea bohlokoa ho sebelisana pakeng tsa microstructure ea ferrite le magnetism..
Ho utloisisa kamano e rarahaneng lipakeng tsa sebopeho, sebopeho le magnetism ke motheo oa ho rala le ho nts'etsapele lits'ebetso tsa nako e tlang.Tlhahlobo ea boemo ba mohala oa mofuta o khethiloeng oa XRPD oa SrFe12O19 o netefalitse sebopeho sa anisotropic sa li-nanocrystals tse fumanoeng ka mokhoa oa rona oa ho kopanya.E kopantsoe le tlhahlobo ea TEM, tlhaho ea polycrystalline ea karoloana ena e ile ea pakoa, 'me ka mor'a moo e tiisitsoe hore boholo ba SFO bo hlahlobiloeng mosebetsing ona bo ne bo le tlase ho feta bophara bo boima ba sebaka se le seng, ho sa tsotellehe bopaki ba khōlo ea crystallite.Motheong ona, re sisinya ts'ebetso ea magnetization e ke keng ea fetoloa e thehiloeng ho thehoeng ha sebaka sa tšebelisano se entsoeng ka likristale tse hokahaneng.Liphetho tsa rona li paka kamano e haufi lipakeng tsa morphology ea likaroloana, sebopeho sa kristale le boholo ba kristale bo teng boemong ba nanometer.Boithuto bona bo ikemiselitse ho hlakisa ts'ebetso ea magnetization ea morao-rao ea lisebelisoa tse thata tsa nanostructured le ho tseba karolo ea likarolo tsa microstructure boitšoarong bo hlahisoang ke matla a khoheli.
Mehlala e ne e entsoe ka ho sebelisa citric acid e le chelating agent / fuel ho ea ka mokhoa oa ho chesa ka mokhoa o sa reroang oa sol-gel, o tlalehiloeng ho Reference 6. Maemo a motsoako a ile a ntlafatsoa ho fumana mefuta e meraro e fapaneng ea lisampole (SFOA, SFOB, SFOC), tse neng li le teng. e fumanoeng ka liphekolo tse nepahetseng tsa li-annealing ka mocheso o fapaneng (1000, 900, le 800 ° C, ka ho latellana).Letlapa la S1 le akaretsa thepa ea makenete mme e fumana hore li batla li tšoana.Nanocomposite SrFe12O19/CoFe2O4 40/60 w/w% le eona e ile ea lokisoa ka tsela e tšoanang.
Sebopeho sa diffraction se ile sa lekanyetsoa ho sebelisoa mahlaseli a CuKα (λ = 1.5418 Å) ho Bruker D8 powder diffractometer, 'me bophara ba sekhahla sa detector se behiloe ho 0.2 mm.Sebelisa k'haonte ea VANTEC ho bokella lintlha ho 2θ ea 10-140°.Mocheso nakong ea ho rekota data o ne o bolokiloe ho 23 ± 1 °C.Pontšo e lekantsoe ka thekenoloji ea mohato le ho hlahloba, 'me bolelele ba mehato ea lisampole tsohle tsa liteko ke 0.013 ° (2theta);boleng bo phahameng ba tlhōrō ea sebaka sa tekanyo ke-2.5 le + 2.5 ° (2theta).Bakeng sa tlhoro e 'ngoe le e' ngoe, ho baloa kakaretso ea li-quanta tse 106, athe mohatleng ho na le li-quanta tse ka bang 3000.Ho ile ha khethoa litlhōrō tse 'maloa tsa liteko (tse arohaneng kapa tse fapanyetsanang ka mokhoa o sa fellang) bakeng sa tlhahlobo e tsoelang pele ka nako e le' ngoe: (100), (110) le (004), tse etsahetseng ka lehlakoreng la Bragg haufi le lehlakoreng la Bragg la mohala oa ngoliso oa SFO.Matla a liteko a ile a lokisoa bakeng sa ntlha ea polarization ea Lorentz, 'me bokamorao bo ile ba tlosoa ka phetoho e nahanoang ea mola.Maemo a NIST a LaB6 (NIST 660b) a sebelisitsoe ho lekanya sesebelisoa le ho pharalla ha spectral.Sebelisa LWL (Louer-Weigel-Louboutin) mokhoa oa ho fokotsa 30,31 ho fumana mela e hloekileng ea diffraction.Mokhoa ona o kengoa ts'ebetsong lenaneong la tlhahlobo ea boemo ba PROFIT-software32.Ho latela lintlha tse lekantsoeng tsa matla a sampole le maemo a nang le ts'ebetso ea pseudo Voigt, ho ntšoa mola o nepahetseng oa khouto f(x).Mosebetsi oa kabo ea boholo G(L) o khethoa ho tloha ho f(x) ka ho latela mokhoa o hlahisitsoeng ho Reference 23. Bakeng sa lintlha tse ling, ka kopo sheba boitsebiso ba tlatsetso.E le tlatsetso ea tlhahlobo ea profil ea line, lenaneo la FULLPROF le sebelisetsoa ho etsa tlhahlobo ea Rietveld ho data ea XRPD (lintlha li ka fumanoa Maltoni et al. 6).Ka bokhutšoane, moetsong oa Rietveld, litlhoro tsa phapano li hlalosoa ke tšebetso e fetotsoeng ea Thompson-Cox-Hastings pseudo Voigt.Ntlafatso ea LeBail ea data e entsoe ho latela maemo a NIST LaB6 660b ho bontša tlatsetso ea sesebelisoa ho atoloseng sehlohlolong.Ho ea ka FWHM e baliloeng (bophara bo felletseng halofong ea sekhahla sa tlhoro), equation ea Debye-Scherrer e ka sebelisoa ho bala boholo bo lekanang le boima ba boholo ba sebaka se kopaneng sa kristale e hasaneng:
Moo λ e leng bolelele ba maqhubu a mahlaseli a X-ray, K ke sebopeho sa sebopeho (0.8-1.2, hangata se lekana le 0.9), 'me θ ke angle ea Bragg.Sena se sebetsa ho: ponts'o e khethiloeng, sete e lumellanang ea lifofane le mokhoa oohle (10-90 °).
Ho feta moo, microscope ea Philips CM200 e sebetsang ho 200 kV le e nang le khoele ea LaB6 e ile ea sebelisoa bakeng sa tlhahlobo ea TEM ho fumana tlhahisoleseding mabapi le morphology ea likaroloana le kabo ea boholo.
Tekanyo ea ho phomola ha Magnetization e etsoa ke lisebelisoa tse peli tse fapaneng: Physical Property Measurement System (PPMS) ho tloha Quantum Design-Vibrating Sample Magnetometer (VSM), e nang le 9 T superconducting magnet, le MicroSense Model 10 VSM e nang le electromagnet.Tšimo ke 2 T, sampole e tletse tšimong (μ0HMAX: -5 T le 2 T, ka ho latellana bakeng sa seletsa se seng le se seng), ebe sebaka se ka morao (HREV) se sebelisoa ho tlisa sampole sebakeng sa switching (haufi le HC ), ebe The magnetization decay e tlalehiloe e le ts'ebetso ea nako e fetang metsotso e 60.Tekanyo e etsoa ho 300 K. Bophahamo bo ts'oanang ba ts'ebetso bo lekoa ho ipapisitsoe le litekanyetso tse lekantsoeng tse hlalositsoeng ho thepa ea tlatsetso.
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