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Insimbi engagqwali esetshenziswa kakhulu kanye nezinguqulo zayo ezikhandiwe zimelana nokugqwala ezimeni ezizungezile ngenxa yongqimba lwe-passivation oluhlanganisa i-chromium oxide. Ukugqwala nokuguguleka kwensimbi kuvame ukuhlotshaniswa nokucekelwa phansi kwalezi zingqimba, kodwa kuyaqabukela nokubukeka kwe-surface inhomogeneities, kuye ngezinga elincane kakhulu. Kulo msebenzi, i-nanoscale chemical surface heterogeneity, etholwe nge-spectroscopic microscopy kanye nokuhlaziywa kwekhemimethrikhi, ibusa ngokungalindelekile ukuphuka nokugqwala kwe-cerium egoqiwe ebandayo eguquliwe i-super duplex stainless steel 2507 (SDSS) phakathi nokuguquka kwayo okushisayo. Nakuba i-X-ray photoelectron microscopy ibonise ukumbozwa okufana ngokuqhathaniswa kongqimba lwemvelo lwe-Cr2O3, ukusebenza kokuphazima kweso kwe-SDSS egoqiwe ebandayo kwakungekuhle ngenxa yokusatshalaliswa kwendawo kwe-Fe3+ nanoislands ecebile kungqimba lwe-Fe/Cr oxide. Lolu lwazi lwesikali se-athomu lunikeza ukuqonda okujulile kokugqwala kwensimbi engagqwali futhi kulindeleke ukuthi lusize ukulwa nokugqwala kwezinsimbi ezifanayo ezinengxubevange ephezulu.
Selokhu kwasungulwa insimbi engagqwali, izinto ezilwa nokugqwala ze-ferrochrome ziye zathintwa i-chromium, eyenza ama-oxide aqinile/i-oxyhydroxides futhi ebonisa ukuziphatha okungahambi kahle ezindaweni eziningi. Uma kuqhathaniswa nezinsimbi ezivamile (i-austenitic ne-ferritic) ezingagqwali 1, 2, 3, izinsimbi ezingenasici ze-super duplex (SDSS) zinokumelana nokugqwala okungcono kanye nezakhiwo ezinhle kakhulu zemishini. Ukwenyuka kwamandla okusebenza kuvumela imiklamo elula futhi ehlangene. Ngokuphambene, i-SDSS yokonga inokumelana okuphezulu nokugqwala kwemigodi nokugqwala, okuholela empilweni yesevisi ende, ngaleyo ndlela yandisa ukusetshenziswa kwayo ekulawuleni ukungcola, iziqukathi zamakhemikhali, kanye nemboni kawoyela negesi yasogwini4. Kodwa-ke, ububanzi obuncane bamazinga okushisa okushisa kanye nokwakheka okungekuhle kuphazamisa ukusetshenziswa kwawo okubanzi okusebenzayo. Ngakho-ke, i-SDSS ishintshiwe ukuze kuthuthukiswe ukusebenza okungenhla. Isibonelo, ukuguqulwa kwe-Ce kwethulwe ku-SDSS 2507 (Ce-2507) enokuqukethwe okuphezulu kwe-nitrogen6,7,8. I-elementi yomhlaba engavamile (Ce) ekuhlanganiseni okufanele kuka-0.08 wt.% inomthelela onenzuzo ezimpahleni zomshini ze-DSS, njengoba ithuthukisa ukuhluzwa okusanhlamvu namandla omngcele wokusanhlamvu. Ukumelana nokugqoka nokugqwala, amandla aqinile namandla okukhiqiza, nokusebenza okushisayo nakho kuyathuthukiswa9. Inani elikhulu le-nitrogen lingathatha indawo yokuqukethwe kwe-nickel ebizayo, okwenza i-SDSS ingabizi kakhulu10.
Muva nje, i-SDSS iye yakhubazeka ngokwepulasitiki emazingeni okushisa ahlukahlukene (cryogenic, cold and hot) ukuze kuzuzwe izakhiwo ezinhle kakhulu zemishini6,7,8. Kodwa-ke, ukumelana okuhle kakhulu kokugqwala kwe-SDSS ngenxa yokuba khona kwefilimu encane ye-oxide ebusweni kuthinteka izici eziningi ezifana nokuhlukahluka okungokwemvelo ngenxa yokuba khona kwezigaba ezihlukene ezinemingcele ehlukene yokusanhlamvu, ukushona okungafuneki nokusabela okuhlukile. ukuguqulwa kwezigaba ze-austenitic kanye ne-ferritic7. Ngakho-ke, ukucwaninga kwesizinda sesizinda esincane samafilimu anjalo kuze kufike ezingeni lesakhiwo se-elekthronikhi kuba semqoka ekuqondeni ukugqwala kwe-SDSS futhi kudinga amasu okuhlola ayinkimbinkimbi. Kuze kube manje, izindlela ezizwela phezulu njenge-Auger electron spectroscopy11 kanye ne-X-ray photoelectron spectroscopy12,13,14,15 kanye ne-X-ray photoemission microscopy eqinile (HAX-PEEM)16 ngokuvamile zehlulekile ukuthola umehluko wamakhemikhali ezingqimbeni ezingaphezulu. izimo zamakhemikhali zento efanayo ezindaweni ezahlukene zesikhala se-nanoscale. Ucwaningo oluningi lwakamuva luhlobanise i-oxidation yendawo ye-chromium nokuziphatha okubonwayo kokugqwala kwe-austenitic stainless steels17, martensitic steels18 kanye ne-SDSS19,20. Kodwa-ke, lezi zifundo zigxile kakhulu emphumeleni we-Cr heterogeneity (isb, isimo se-Cr3+ oxidation) ekumelaneni nokugqwala. I-Lateral heterogeneity ezimeni ze-oxidation zezakhi zingabangelwa izinhlanganisela ezihlukene ezinezakhi ezifanayo, njengama-iron oxides. Lezi zinhlanganisela, ezizuze usayizi omncane ngenxa yokwelashwa kwe-thermomechanical, ziseduze komunye nomunye, kodwa zihluke ekubunjweni kanye nesimo se-oxidation16,21. Ngakho-ke, ukuze uthole ukuqhekeka kwamafilimu e-oxide kanye nokugoba okulandelayo, kuyadingeka ukuqonda ukuhlukahluka kwendawo ezingeni le-microscopic. Naphezu kwalezi zidingo, izilinganiso zobuningi ezifana ne-lateral heterogeneity ku-oxidation, ikakhulukazi ku-Fe esikalini se-nano- ne-athomu, zisantuleka, futhi ukuhlobana kwayo nokumelana nokugqwala kuhlala kungakahlolwa. Kuze kube muva nje, isimo samakhemikhali sezakhi ezihlukahlukene, njenge-Fe ne-Ca22, kumasampula ensimbi aye abonakala ngobuningi kusetshenziswa i-X-ray photoelectron microscopy (X-PEEM) ezinsizeni zemisebe ye-nanoscale synchrotron. Ihlanganiswe ne-X-ray ye-absorption spectroscopy (XAS) ezwela amakhemikhali amakhemikhali, i-X-PEEM yenza izilinganiso ze-XAS zibe nokulungiswa okuphezulu kwendawo nokubukeka, ihlinzeka ngolwazi lwamakhemikhali mayelana nokwakheka kwezinto kanye nesimo sazo samakhemikhali ngokulungiswa kwendawo kuze kufike esikalini se-nanometer esingamashumi amabili nantathu. . Lokhu kubuka kwe-spectromicroscopic kokuqala kusiza ukubhekwa kwamakhemikhali endawo futhi kungabonisa izinguquko zamakhemikhali endaweni yongqimba lwensimbi olungakaze luphenywe ngaphambilini.
Lolu cwaningo lunweba izinzuzo ze-PEEM ekutholeni umehluko wamakhemikhali ku-nanoscale futhi luveza indlela yokuhlaziya indawo ye-athomu yezinga le-athomu yokuqonda ukuziphatha kokugqwala kwe-Ce-2507. Isebenzisa indlela yekhemimethri ehlanganisiwe ye-K-means24 ukuze kumephu ikhemikhali yomhlaba wonke (hetero)homogeneity yezinto ezihilelekile, izimo zazo zamakhemikhali ezethulwa ngokomfanekiso wezibalo. Ngokuphambene nokugqwala okuqalwe ukucekelwa phansi kwefilimu ye-chromium oxide esimweni sendabuko, ukudlula kancane kanye nokumelana nokugqwala okuphansi okwamanje kubangelwa ama-nanoislands acebile e-Fe3+ eduze nongqimba lwe-Fe/Cr oxide, okungenzeka kube yizinto zokuvikela. I-oxide ibhubhisa ifilimu enamachashazi futhi ibangele ukugqwala.
Ukuziphatha okulimazayo kwe-SDSS 2507 ekhubazekile kwaqale kwahlolwa kusetshenziswa izilinganiso ze-electrochemical. Emkhiwaneni. Umfanekiso 1 ubonisa amajika e-Nyquist kanye ne-Bode kumasampuli akhethiwe kusixazululo esine-asidi (pH = 1) se-FeCl3 kuzinga lokushisa legumbi. I-electrolyte ekhethiwe isebenza njenge-ejenti ene-oxidizing eqinile, ebonisa ukuthambekela kwefilimu ye-passivation ukuphuka. Nakuba okokusebenza kungazange kungene emgodini ozinzile ezingeni lokushisa legumbi, ukuhlaziya kunikeze ukuqonda ezenzakalweni ezingase zehluleke kanye nokugqwala okwalandela. Isifunda esilinganayo (I-Fig. 1d) sisetshenziselwa ukulinganisa i-spectrum ye-electrochemical impedance spectroscopy (EIS), futhi imiphumela ehambisanayo ehambisanayo iboniswa kuThebula 1. Ama-semicircles angaphelele avela ku-specimens ephathwa ngesisombululo futhi esebenza ngokushisa, kuyilapho ama-semicircles acindezelwe avela kuma-cold rolled counterparts (Fig. Ku-spectroscopy ye-EIS, i-radius ye-semicircle ingabhekwa njengokumelana ne-polarization (Rp) 25,26. I-Rp yomzila wezindiza onesixazululo kuThebula 1 icishe ibe ngu-135 kΩ cm–2, nokho, amanani omzila wezindiza osebenza okushisayo noma ogoqelwe ngokubanda aphansi kakhulu, 34.7 kanye no-2.1 kΩ cm–2, ngokulandelana. Lokhu kuncipha okuphawulekayo kwe-Rp kubonisa umphumela olimazayo we-deformation ye-plastic on passivation and corrosion resistance, njengoba kuboniswe emibikweni yangaphambilini27,28,29,30.
i-Nyquist, b, c I-Bode impedance kanye nemidwebo yesigaba, kanye no-d amamodeli esekethe afanayo ahambisanayo, lapho i-RS iwukumelana ne-electrolyte, i-Rp iwukumelana ne-polarization, futhi i-QCPE iyi-oxide yesici sesigaba esingaguquki esisetshenziselwa ukumodela amandla angafanelekile (n). Izilinganiso ze-EIS zenziwa endaweni evulekile yesekethe.
Ama-constants kanyekanye aboniswa esakhiweni se-Bode, enethafa elikububanzi obuphezulu befrikhwensi emele ukumelana ne-electrolyte RS26. Njengoba imvamisa iyancipha, i-impedance iyanda futhi i-angle yesigaba esingalungile itholakala, ekhombisa ukubusa kwe-capacitance. I-engeli yesigaba iyakhula, igcine ubuningi phezu kobubanzi bemvamisa ebanzi ngokuqhathaniswa, bese yehla (Fig. 1c). Kodwa-ke, kuzo zontathu izimo, lesi sibalo esiphezulu sisengaphansi kuka-90°, okubonisa ukuziphatha okuhle kwe-capacitive ngenxa yokuhlakazeka kwe-capacitive. Ngakho-ke, isici sesigaba esiqhubekayo se-QCPE (CPE) sisetshenziselwa ukumela ukusabalalisa kwe-interfacial capacitance okuvela ekuqineni kwendawo noma ukungahambi kahle, ikakhulukazi esikalini se-athomu, i-geometry ye-fractal, i-electrode porosity, i-non-uniform potential, ne-geometry enesimo se-electrodes31,32. I-CPE impedance:
lapho u-j eyinombolo engokomfanekiso futhi u-ω kuyi-angular frequency. I-QCPE iyimvamisa ezimele engaguquki elingana nendawo evulekile esebenzayo ye-electrolyte. n iyinombolo yamandla angenasici echaza ukuchezuka kwe-capacitor ukusuka kumandla afanelekile, okusho ukuthi ukusondela kuka-n kuya ku-1, i-CPE eseduze iwukuba namandla, kuyilapho uma u-n esondele ku-zero, ibonakala iphikisana. Ukuchezuka okuncane kwe-n, eduze noku-1, kubonisa ukuziphatha okungafanelekile kwe-capacitive ebusweni ngemva kokuhlolwa kwe-polarization. I-QCPE ye-SDSS egoqiwe ebandayo iphakeme kakhulu kunozakwabo, okusho ukuthi ikhwalithi engaphezulu ayifani kangako.
Ngokuvumelana nezakhiwo eziningi zokungagqwali kwezinsimbi, okuqukethwe okuphezulu kwe-Cr kwe-SDSS ngokuvamile kubangela ukumelana okuhle kakhulu nokugqwala kwe-SDSS ngenxa yokuba khona kwefilimu ye-oxide evikelayo endaweni17. Amafilimu anjalo adlulayo ngokuvamile acebile ngama-Cr3+ oxides kanye/noma ama-hydroxides, ikakhulukazi ahlanganiswe ne-Fe2+, Fe3+ oxides kanye/noma (oxy)hydroxides33. Naphezu kokufana kwendawo efanayo, ungqimba lwe-oxide odlulayo, futhi akukho ukuqhekeka kwendawo okubonwayo ngokwezilinganiso ezincane kakhulu6,7, ukuziphatha kokugqwala kwe-SDSS esebenza ngokushisayo negoqwe ngokubanda kuhlukile, ngakho ucwaningo olujulile lwezimpawu ze-microstructural luyadingeka ukuze kuguqulwe insimbi.
I-microstructure yensimbi engagqwali ekhubazekile yacwaningwa ngobuningi kusetshenziswa ama-X-ray anamandla angaphakathi kanye nama-synchrotron (Izibalo Ezingeziwe 1, 2). Ukuhlaziya okuningiliziwe kunikezwa Olwazini Olwengeziwe. Nakuba kukhona ukuvumelana okuvamile ngohlobo lwesigaba esikhulu, ukuhluka kwezigaba zesigaba sobuningi kutholwe, okufakwe kuhlu Lokwengeza Ithebula 1. Lo mehluko ungahle ubangelwe yizingxenye zesigaba esingena-homogeneous phezulu kanye nevolumu, ezithintwa ukujula kokutholwa kwe-X-ray diffraction (XRD) ehlukene. ) ngemithombo yamandla ehlukene yesigameko ama-photons34. Izingxenye eziphakeme ngokuqhathaniswa ze-austenite ezicini ezigoqiwe ezibandayo ezinqunywe i-XRD ezivela emthonjeni waselabhorethri zikhombisa ukudlula okungcono bese kuba ngcono ukumelana nokugqwala35, kuyilapho imiphumela enembe kakhudlwana nezibalo iphakamisa izitayela eziphambene kumafrakshini wesigaba. Ukwengeza, ukumelana nokugqwala kwensimbi nakho kuncike ezingeni lokulungiswa okusanhlamvu, ukunciphisa usayizi wokusanhlamvu, ukwanda kwe-microdeformations kanye nomthamo we-dislocation okwenzeka ngesikhathi sokwelashwa kwe-thermomechanical36,37,38. Ama-specimens ashisiwe abonisa imvelo enezinhlamvu eziningi, ekhombisa okusanhlamvu okungama-micron, kuyilapho amasongo abushelelezi abonwa kuma-specimens abandayo (I-Supplementary Fig. 3) ayebonisa ukuthuthukiswa okusanhlamvu okubalulekile ukuze kusetshenziswe i-nanosize emsebenzini wangaphambilini. Lokhu kufanele kuvumela ifilimu ye-passive. ukwakheka kanye nokwanda kokumelana nokugqwala. Ukuminyana okuphezulu kokugudluka kuvame ukuhlotshaniswa nokumelana okuphansi nokugoba, okuvumelana kahle nezilinganiso ze-electrochemical.
Izinguquko esimweni samakhemikhali se-microdomains yezinto eziyinhloko zafundwa ngokuhlelekile kusetshenziswa i-X-PEEM. Nakuba kunezici eziningi ze-alloying, i-Cr, i-Fe, i-Ni ne-Ce39 ikhethiwe lapha, njengoba i-Cr iyisici esibalulekile sokwenza ifilimu ye-passive, i-Fe iyingxenye eyinhloko yensimbi, futhi i-Ni ithuthukisa u-passivation futhi ibhalansise isigaba se-ferrite-austenitic. Isakhiwo nokuguqulwa kuyinhloso ye-Ce. Ngokulungisa amandla e-synchrotron beam, i-XAS ithwebule izici eziyinhloko ze-Cr (L2.3 onqenqemeni), i-Fe (L2.3 edge), i-Ni (L2.3 edge), kanye ne-Ce (M4.5 edge) ukusuka phezulu. -2507 SDSS. Ukuhlaziywa kwedatha okufanele kwenziwe ngokuhlanganisa ukulinganiswa kwamandla nedatha eshicilelwe (isb. I-XAS ku-Fe L2, izimbambo ezi-340,41).
Emkhiwaneni. Umfanekiso we-2 ubonisa izithombe ze-X-PEEM ze-hot-worked (Fig. 2a) kanye ne-cold-rolled (Fig. 2d) Ce-2507 SDSS kanye ne-XAS Cr kanye ne-Fe L2,3 imiphetho ehambisanayo ezindaweni ezimakwe ngazinye. Unqenqema lwe-L2,3 XAS luhlola izimo ezingasebenzi ezingu-3d zama-electron ngemva kwe-photoexcitation ku-2p3/2 (L3 edge) kanye namazinga okuhlukanisa angu-2p1/2 (L2 onqenqemeni) we-spin. Ulwazi mayelana nesimo se-valence se-Cr lutholwe ekuhlaziyweni kwe-X-ray diffraction yonqenqema lwe-L2,3 ku-Fig. 2b,d. Isixhumanisi sokuqhathanisa. 42, 43 ibonise ukuthi iziqongo ezine u-A (578.3 eV), B (579.5 eV), C (580.4 eV), kanye no-D (582.2 eV) zibonwe eduze komphetho we-L3, okubonisa ama-ion e-octahedral Cr3+, ahambisana ne-Cr2O3. I-spectra yokuhlola ivumelana nezibalo zethiyori, njengoba kuboniswe kumaphaneli u-b no-e, atholwe ekubalweni kwenkundla yekristalu eminingi kusixhumi esibonakalayo se-Cr L2.3 kusetshenziswa inkambu yekristalu engu-2.0 eV44. Zombili izindawo ze-SDSS esebenza ngokushisayo negoqwe ngokubanda zimbozwe ngongqimba olufana nolunye lwe-Cr2O3.
isithombe esishisayo se-X-PEEM se-SDSS esakhiwe ngokushisayo esihambisana nonqenqema b Cr L2.3 kanye nonqenqema c Fe L2.3, d Isithombe esishisayo esingu-X-PEEM se-SDSS egoqwe ngokubandayo esihambisana nonqenqema lwe-e Cr L2.3 kanye ne-f Fe L2.3 yohlangothi (e) . I-spectra ye-XAS efakwe ezindaweni ezihlukahlukene ezimakwe ezithombeni ezishisayo (a, d) ngemigqa enamachashazi awolintshi kokuthi (b) kanye no-(e) imele isibukeli esilingisiwe se-XAS se-Cr3+ enenani lenkundla yekristalu elingu-2.0 eV. Ezithombeni ze-X-PEEM, iphalethi eshisayo isetshenziselwa ukuthuthukisa ukufundeka kwesithombe, lapho imibala esuka kokuluhlaza okwesibhakabhaka iye kokubomvu ilingana nokuqina kokumuncwa kwe-X-ray (kusuka phansi kuye phezulu).
Kungakhathaliseki ukuthi imvelo yamakhemikhali yalezi zakhi zensimbi, isimo samakhemikhali sokungezwa kwezakhi ze-alloying ze-Ni ne-Ce kuwo womabili amasampuli sahlala sinjalo. Umdwebo owengeziwe. Emkhiwaneni. I-5-9 ibonisa izithombe ze-X-PEEM kanye ne-spectra ye-XAS ehambisanayo ye-Ni ne-Ce ezindaweni ezihlukahlukene endaweni yezibonelo ezishisiwe nezigoqelwe ngokubanda. I-Ni XAS ibonisa isimo se-oxidation se-Ni2+ phezu kwayo yonke indawo elinganiselwe yezibonelo ezishisiwe nezigoqelwe ngokubanda (Ingxoxo Eyengeziwe). Kuyaphawuleka ukuthi endabeni yezibonelo ezishisiwe, isignali ye-XAS ye-Ce ayibonwa, kuyilapho i-spectrum ye-Ce3+ yesampula egoqwe ngokubanda ibonwa ngesikhathi esisodwa. Ukubhekwa kwamachashazi e-Ce kumasampuli agoqelwe ngokubanda kubonise ukuthi i-Ce ikakhulukazi ikhona ngendlela yemvula.
Ku-SDSS ekhubazekile ngokushisa, alukho ushintsho lwesakhiwo sendawo ku-XAS olubonwe emaphethelweni e-Fe L2.3 (Fig. 2c). Nokho, njengoba kuboniswe fig. I-2f, i-matrix ye-Fe ishintsha kancane isimo sayo samakhemikhali ezindaweni eziyisikhombisa ezikhethwe ngokungahleliwe ku-SDSS egoqiwe ebandayo. Ukwengeza, ukuze uthole umqondo onembile wezinguquko esimweni se-Fe ezindaweni ezikhethiwe ku-Fig. 2f, izifundo zendawo zendawo zenziwa (Fig. 3 kanye ne-Supplementary Fig. 10) lapho izifunda ezincane eziyindilinga zikhethiwe. I-spectra ye-XAS yomkhawulo we-Fe L2,3 wezinhlelo ze-α-Fe2O3 kanye ne-Fe2+ octahedral oxides zenziwe imodeli kusetshenziswa izibalo zenkundla yekristalu ephindaphindwayo kusetshenziswa izinkambu zekristalu ze-1.0 (Fe2+) kanye ne-1.0 (Fe3+)44. Siyaqaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inenhlanganisela yakho kokubili i-Fe2+ & Fe3+,47, kanye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2+ oxide (3d6). Siyaqaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inenhlanganisela yakho kokubili i-Fe2+ & Fe3+,47, kanye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2+ oxide (3d6).Qaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 ihlanganisa kokubili i-Fe2+ ne-Fe3+,47 kanye ne-FeO45 ngendlela ye-divalent oxide Fe2+ (3d6).Qaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inezinhlanganisela ze-Fe2+ ne-Fe3+,47 kanye ne-FeO45 isebenza njenge-divalent esemthethweni i-Fe2+ oxide (3d6). Wonke ama-Fe3+ ion ku-α-Fe2O3 anezikhundla ze-Oh kuphela, kuyilapho i-γ-Fe2O3 ivamise ukuvezwa njenge-Fe3+ t2g [Fe3+5/3V1/3]isb i-O4 spinel enezikhala eg izikhundla. Ngakho-ke, ama-Fe3+ ion ku-γ-Fe2O3 anezindawo zombili ze-Td ne-Oh. Njengoba kushiwo emsebenzini odlule, nakuba izilinganiso zokuqina kokubili zihlukile, isilinganiso sazo sokuqina isb/t2g singu-≈1, kuyilapho kulesi simo isilinganiso sokuqina esibhekwayo isb/t2g sicishe sibe ngu-1. Lokhu kukhipha ukuthi kungenzeka kube khona i-Fe3+ kuphela kuleli cala. Uma kucatshangelwa isimo se-Fe3O4 nezinhlanganisela ze-Fe2+ ne-Fe3+, kuyaziwa ukuthi isici sokuqala esibuthakathaka (esiqinile) esinqeni se-L3 se-Fe sibonisa ukungabi khona kwabantu okuncane (okukhulu) kusimo se-t2g. Lokhu kusebenza ku-Fe2+ (Fe3+), okubonisa ukwanda kophawu lokuqala olubonisa ukwanda kokuqukethwe kwe-Fe2+47. Le miphumela ibonisa ukuthi i-Fe2+ ne-γ-Fe2O3, α-Fe2O3 kanye/noma i-Fe3O4 ivelele ezindaweni ezigoqeke ezibandayo zezinhlanganisela.
Izithombe ezishisayo ze-electron ezinwetshiwe ze-(a, c) kanye (b, d) ne-XAS spectra ngaphesheya konqenqema lwe-Fe L2,3 ezindaweni ezihlukahlukene zendawo phakathi kwezifunda ezikhethiwe 2 kanye no-E kumakhiwane. 2d.
Idatha yokuhlola etholiwe (I-Fig. 4a kanye ne-Supplementary Fig. 11) yahlelwa futhi yaqhathaniswa naleyo ye-compounds ehlanzekile 40, 41, 48. Ngokuyisisekelo, izinhlobo ezintathu ezihlukene zokubonwa kokuhlolwa kwe-Fe L-edge XAS spectra (XAS-1, XAS-2 kanye ne-XAS-3: I-Fig. 4a) yabonwa endaweni ehlukile yendawo. Ikakhulukazi, i-spectrum efana ne-2-a (ekhonjwe njenge-XAS-1) ku-Fig. 3b ibonwe kuso sonke isifunda sentshisakalo, ilandelwa i-spectrum engu-2-b (ebhalwe ukuthi XAS-2), kuyilapho i-spectrum efana ne-E-3 ibonwa kufig. I-3d (ebizwa ngokuthi i-XAS-3) ibonwe ezindaweni ezithile zendawo. Ngokuvamile, amapharamitha amane asetshenziselwa ukukhomba izifunda ze-valence ezikhona kusampula ye-probe: (1) L3 kanye ne-L2 izici ze-spectral, (2) izindawo zamandla ze-L3 nezici ze-L2, (3) umehluko wamandla we-L3-L2, (4) isilinganiso sokuqina kwe-L2 / L3. Ngokokubuka okubukwayo (Fig. 4a), zontathu izingxenye ze-Fe, okuyi-Fe0, Fe2+, kanye ne-Fe3+, zikhona ebusweni be-SDSS efundwayo. Isilinganiso sokuqina esibaliwe esingu-L2/L3 siphinde sabonisa ukuba khona kwazo zonke izingxenye ezintathu.
a Kuqashelwe idatha yokuhlola emithathu ehlukile (imigqa eqinile i-XAS-1, XAS-2 kanye ne-XAS-3 ihambelana no-2-a, 2-b kanye ne-E-3 ku-Fig. 2 kanye ne-Fig. 3) uma kuqhathaniswa nokulingisa i-XAS Comparison spectra, ama-octahedron Fe2+, Fe3+, amanani e-crystal field of 1.0-V ered, 1.5-V ered, 1. idatha yokuhlola (i-XAS-1, i-XAS-2, i-XAS-3) nedatha ye-LCF ehambisanayo elungiselelwe (umugqa omnyama oqinile), nokuqhathanisa i-spectra ye-XAS-3 ne-Fe3O4 (isimo esixubile se-Fe) kanye ne-Fe2O3 (i-Fe3+ emsulwa) namazinga.
Inhlanganisela yomugqa (LCF) ukulingana kwamazinga amathathu40,41,48 yasetshenziselwa ukulinganisa ukwakheka kwe-iron oxide. I-LCF yasetshenziswa ku-spectra ye-Fe L-edge XAS ekhethiwe ebonisa ukugqama okuphezulu kakhulu, okuyi-XAS-1, XAS-2 ne-XAS-3, njengoba kuboniswe ku-Fig. 4b–d. Kokufakwayo kwe-LCF, u-10% Fe0 ucatshangelwe kuzo zonke izimo ngenxa yomugqa omncane esiwubonile kuyo yonke idatha kanye neqiniso lokuthi insimbi eyinsimbi iyingxenye eyinhloko yensimbi. Ngempela, ukujula kokuhlolwa kwe-X-PEEM kwe-Fe (~6 nm) 49 kukhulu kunogqinsi olulinganiselwe lwengqimba ye-oxidation (kancane> 4 nm), okuvumela ukutholwa kwesignali ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. Ngempela, ukujula kokuhlolwa kwe-X-PEEM kwe-Fe (~6 nm) 49 kukhulu kunogqinsi olulinganiselwe lwengqimba ye-oxidation (kancane> 4 nm), okuvumela ukutholwa kwesignali ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. Действительно, пробная глубина X-PEEM для Fe (~ 6 нм)49 больше, чем предполагаемая толщина слоя окисления (немного > 4 нзолья что сигнал от железной матрицы (Fe0) под пассивирующим слоем. Ngempela, ukujula kwe-probe X-PEEM kwe-Fe (~ 6 nm) 49 kukhulu kunokuqina okucatshangwayo kwesendlalelo se-oxidation (kancane> 4 nm), okwenza kube nokwenzeka ukuthola isignali ku-matrix yensimbi (Fe0) ngaphansi kongqimba lwe-passivation.Eqinisweni, i-X-PEEM ithola i-Fe (~6 nm) ijule ngo-49 kunokujiya okulindelekile kongqimba lwe-oxide (ngaphezudlwana kuka-4 nm), okuvumela ukutholwa kwamasignali asuka ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. Izinhlanganisela ezihlukahlukene ze-Fe2+ ne-Fe3+ zenziwe ukuze kutholwe isisombululo esingcono kakhulu sedatha yokuhlola ebhekiwe. Emkhiwaneni. Umfanekiso 4b ubonisa inhlanganisela ye-Fe2+ ne-Fe3+ ku-spectrum ye-XAS-1, lapho ukulinganiswa kwe-Fe2+ ne-Fe3+ kuseduze, cishe u-45%, okubonisa isimo se-oxidation esixubile se-Fe. Nakuba ku-spectrum ye-XAS-2, iphesenti le-Fe2+ ne-Fe3+ iba ngu-~30% no-60%, ngokulandelanayo. Okuqukethwe kwe-Fe2+ kungaphansi kwalokho kwe-Fe3+. Isilinganiso se-Fe2+ kuya ku-Fe3 sika-1:2 sisho ukuthi i-Fe3O4 ingakhiwa ngesilinganiso esifanayo sama-ion e-Fe. Ngaphezu kwalokho, ku-spectrum ye-XAS-3, amaphesenti e-Fe2+ ne-Fe3+ ashintshele ku-~10% no-80%, okubonisa ukuguqulwa okuphezulu kwe-Fe2+ kuya ku-Fe3+. Njengoba kushiwo ngenhla, i-Fe3+ ingavela ku-α-Fe2O3, γ-Fe2O3 noma ku-Fe3O4. Ukuze uqonde umthombo okungenzeka kakhulu we-Fe3+, i-XAS-3 spectra ihlelwa ngokuhambisana namazinga ahlukahlukene e-Fe3+ ku-Fig. 4e ebonisa ukufana nawo wonke amazinga amabili lapho kucatshangelwa I-Peak B. Nokho, ukushuba kwehlombe (A: kusuka ku-Fe2+) kanye nesilinganiso sokuqina B/A kubonisa ukuthi i-spectrum ye-XAS-3 iseduze kodwa ayifani naleyo ye-γ-Fe2O3. Uma kuqhathaniswa nenqwaba ye-γ-Fe2O3, ukushuba kwe-Fe 2p XAS kokuphakama kwe-A SDSS kuphakeme kancane (I-Fig. 4e), okubonisa ukuqina kwe-Fe2+ okuphezulu. Nakuba i-spectrum ye-XAS-3 ifana ne-γ-Fe2O3, lapho i-Fe3+ ikhona kuzo zombili izindawo ze-Oh ne-Td, ukuhlonzwa kwezifunda ezihlukene ze-valence kanye nokuxhumana kuphela ngonqenqema lwe-L2,3 noma isilinganiso sokuqina se-L2/L3 kuseyinkinga. isihloko esiqhubekayo sengxoxo ngenxa yobunkimbinkimbi bezinto ezihlukahlukene ezihilelekile ku-spectrum yokugcina41.
Ngokungeziwe ekubandlululweni okubonakalayo kwezimo zamakhemikhali zezifunda ezikhethiwe zentshisakalo ezichazwe ngenhla, ukuhlukahluka kwamakhemikhali emhlabeni wonke kwezinto ezibalulekile i-Cr ne-Fe kwahlolwa ngokuhlukanisa yonke imibukiso ye-XAS etholwe endaweni eyisampula kusetshenziswa indlela yokuhlanganisa ye-K-indlela yokuhlanganisa. Amaphrofayili asemaphethelweni e-Cr L asethwe ngendlela yokuthi akhe amaqoqo amabili alungile asatshalaliswa ngokwendawo kuma-specimens asetshenziwe ashisayo nagoqelwe ngokubanda aboniswe kumakhiwane. 5. Kuyacaca ukuthi azikho izinguquko zesakhiwo esiye zabonwa, njengoba amasentimitha amabili e-XAS Cr spectra afana kakhulu. Lezi zimo ze-spectral zamaqoqo amabili zicishe zifane nalezo ezihambisana ne-Cr2O342, okusho ukuthi izendlalelo ze-Cr2O3 zisatshalaliswa ngokulinganayo phezu kwe-SDSS.
iqoqo lezifunda ze-K-kusho i-L-edge Cr, b ehambisana nama-XAS centroids. Imiphumela ye-K-isho i-X-PEEM ukuqhathaniswa kwe-SDSS egoqelwe ngokubanda: amaqoqo ezifunda ezinqenqemeni ze-K ze-Cr L2,3 kanye ne-d ehambisana nama-XAS centroids.
Ukubonisa imephu yonqenqema ye-FeL eyinkimbinkimbi, amaqoqo athuthukisiwe amane nanhlanu kanye nama-centroids ahlotshaniswa nawo (ukusabalalisa okubonakalayo) asetshenziselwa izifanekiso ezisebenza ngokushisayo nezigoqelwe ngokubanda, ngokulandelana. Ngakho-ke, iphesenti (%) ye-Fe2 + ne-Fe3 + ingatholakala ngokulungisa i-LCF eboniswe ku-Fig.4. I-pseudoelectrode engaba khona i-Epseudo njengomsebenzi we-Fe0 isetshenziselwe ukuveza i-microchemical inhomogeneity yefilimu ye-surface oxide. I-Epseudo ilinganiselwa kumthetho wokuxuba,
lapho \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) ilingana \(\rm{Fe} + 2e^ – \to\rm { Fe}^{2 + (3 + )}\), okungu-0.440 kanye no-0.036 V, ngokulandelanayo. Izindawo ezinamandla aphansi zinokuqukethwe okuphezulu kwezinhlanganisela ze-Fe3+. Ukusatshalaliswa okungaba khona kusampula ekhubazekile kunohlamvu olugqinsi olunoshintsho olukhulu olungaba ngu-0.119 V (Fig. 6a,b). Lokhu kusatshalaliswa okungenzeka kuhlobene eduze ne-topography yendawo (Fig. 6a). Azikho ezinye izinguquko ezihlobene nesimo ezibonwe ngaphakathi kwe-lamellar yangaphakathi (Fig. 6b). Ngokuphambene nalokho, ekuhlanganisweni kwama-oxide ahlukene anokuqukethwe okuhlukile kwe-Fe2+ ne-Fe3+ ku-SDSS egoqelwe ngokubanda, imvelo engeyona iyunifomu ye-pseudopotential ingabonwa (Fig. 6c, d). I-Fe3+ oxides kanye/noma (i-oxy)hydroxides yizingxenye eziyinhloko zokugqwala kwensimbi futhi zikwazi ukungena emoyeni nasemanzini50. Kulokhu, kungabonakala ukuthi iziqhingi ezicebile ku-Fe3+ zisatshalaliswa endaweni futhi zingathathwa njengezindawo zokugqwala. Kulesi simo, i-gradient endaweni engaba khona, kunevelu eliphelele lamandla, ingabhekwa njengenkomba yokwenziwa kwendawo kwezifunda ezisebenzayo zokugqwala51. Lokhu kusatshalaliswa kwe-Fe2+ ne-Fe3+ ngendlela elinganayo ebusweni be-SDSS egoqiwe ebandayo kungashintsha izakhiwo zamakhemikhali endawo futhi kunikeze indawo engaphezulu esebenza kahle kakhulu ekuqhekekeni kwefilimu ye-oxide nokusabela kokugqwala, ngaleyo ndlela kuvumele i-matrix yensimbi engaphansi ukuthi igqwele ngokuqhubekayo, okuholela ekungangeni kwehomogeneity yangaphakathi. futhi unciphise izici zokuvikela zesendlalelo esidlulayo.
Amaqoqo e-K-mean wezifunda ezinqenqemeni ze-Fe L2,3 kanye nama-XAS centroids ahambisanayo we-X-PEEM esebenza ngokushisayo ye-a–c kanye ne-d–f egoqeka ebandayo ye-SDSS. a, d K-isho isakhiwo seqoqo esimbozwe esithombeni se-X-PEEM. Amandla e-pseudoelectrode (epseudo) alinganiselwe ashiwo kanye nemidwebo yeqoqo le-K-means. Ukukhanya kwesithombe se-X-PEEM esifana nombala ku-Fig. 2 kuhambisana ngokuqondile namandla okumuncwa kwe-X-ray.
Ngokulinganiselwe i-Cr efanayo kodwa isimo samakhemikhali esihlukile se-Fe siholela kumsuka ohlukile wokuqhekeka kwefilimu ye-oxide namaphethini okugqwala ku-Ce-2507 egoqelwe ngokushisayo nabandayo. Le ndawo ye-Ce-2507 egoqwe ebandayo yaziwa kakhulu. Mayelana nokwakhiwa kwama-oxide nama-hydroxides ka-Fe emoyeni womoya, lokhu kusabela okulandelayo kuvaliwe kulo msebenzi njengokusabela okungathathi hlangothi:
Ngokusekelwe esilinganisweni se-X-PEEM, ukusabela okungenhla kwenzeke ezimeni ezilandelayo. Ihlombe elincane elihambisana ne-Fe0 lihlotshaniswa nensimbi eyinsimbi engaphansi. Ukusabela kwe-metallic Fe nendawo ezungezile kuholela ekwakhekeni kwesendlalelo se-Fe(OH)2 (isibalo (5)), esikhulisa isignali ye-Fe2+ ku-XAS yomkhawulo we-L we-Fe. Ukuchayeka isikhathi eside emoyeni kuzoholela ekwakhekeni kwe-Fe3O4 kanye/noma i-Fe2O3 oxides ngemva kwe-Fe(OH)252,53. Izinhlobo ezimbili ze-Fe, i-Fe3O4 ne-Fe2O3, zingase futhi zakhe ku-Cr3 + ungqimba olucebile lokuvikela, lapho i-Fe3O4 ikhetha khona umfaniswano kanye nesakhiwo esihlangene. Ukuba khona kwayo yomibili imiphumela kuzimo ezixubile ze-oxidation (i-XAS-1 spectrum). I-spectrum ye-XAS-2 ihambelana kakhulu ne-Fe3O4. Nakuba i-spectra ye-XAS-3 ebonwe ezindaweni ezimbalwa ibonise ukuguqulwa okuphelele ku-γ-Fe2O3. Njengoba ama-X-ray angasoliwe anokujula kokungena okungaba ngu-50 nm, isignali evela kungqimba engaphansi iphumela ekushubeni okuphezulu kwesiqongo esingu-A.
I-spectrum ye-XRD ibonisa ukuthi ingxenye ye-Fe kufilimu ye-oxide inesakhiwo esinezingqimba, esihlanganiswe nongqimba lwe-Cr oxide. Ngokuphambene nesici sokwamukela ukugqwala ngenxa ye-inhomogeneity yendawo ye-Cr2O317, ngaphandle kongqimba olufanayo lwe-Cr2O3 kulolu cwaningo, ukumelana nokugqwala okuphansi kubonwe kulesi simo, ikakhulukazi kumasampuli agoqelwe ngokubanda. Ukuziphatha okuphawuliwe kungaqondwa njengokungafani kwesimo se-chemical oxidation yesendlalelo esiphezulu (Fe) esithinta ukusebenza kokugqwala. Ukudluliswa kancane kwe-ion yensimbi noma i-oxygen ku-lattice ngenxa ye-stoichiometry efanayo ephezulu (i-Fe oxide) nezingqimba ezingezansi (i-Cr oxide) i-52,53 iholela ekusebenzisaneni okungcono (ukunamathela) phakathi kwabo. Lokhu-ke kuthuthukisa ukumelana nokugqwala. Ngakho-ke, i-stoichiometry eqhubekayo, okungukuthi isimo esisodwa se-oxidation se-Fe, kungcono kunezinguquko ezisheshayo ze-stoichiometric. I-SDSS ekhubazekile ngokushisa inendawo efanayo kanye nongqimba oluqinile lokuvikela, olunikeza ukumelana nokugqwala okungcono. Kodwa-ke, ku-SDSS egoqekile ebandayo, ukuba khona kweziqhingi ezicebile ze-Fe3 + ngaphansi kwesendlalelo sokuzivikela kubulala ubuqotho bobuso futhi kubangela ukugqwala kwe-galvanic ye-substrate eseduze, okuholela ekunciphiseni kwe-Rp (Ithebula 1) ku-spectra ye-EIS kanye nokugqwala kwayo. ukumelana. Ngakho-ke, iziqhingi ezisatshalaliswa endaweni ezicebile nge-Fe3+ ngenxa yokuguqulwa kwepulasitiki ikakhulukazi zithonya ukusebenza kokumelana nokugqwala, okuwumphumela kulo msebenzi. Ngakho-ke, lolu cwaningo luveza ama-spectromicrographs okunciphisa ukumelana nokugqwala ngenxa yokuguqulwa kwepulasitiki kwamasampula e-SDSS afundwayo.
Ngaphezu kwalokho, nakuba ukuhlanganiswa komhlaba okungavamile ezinsimbi zezigaba ezimbili kusebenza kangcono, ukusebenzisana kwalesi sici esingeziwe ne-matrix yensimbi ngayinye ngokuya ngokuziphatha kokugqwala kuhlala kungenangqondo ngokusekelwe ekubonweni kwe-spectroscopic microscopy. Isiginali ye-Ce (egudle unqenqema lwe-XAS M) ivela kuphela ezindaweni ezimbalwa ngesikhathi sokugoqeka okubandayo, kodwa iyanyamalala ngesikhathi sokuguqulwa okushisayo kwe-SDSS, okubonisa ukubekwa kwendawo kwe-Ce ku-matrix yensimbi esikhundleni sengxubevange ye-homogeneous. Nakuba izakhiwo zemishini ye-SDSS zingathuthukisiwe6,7, ukuba khona kwe-REE kunciphisa usayizi wezinto ezifakiwe futhi kucatshangwa ukuthi kucindezela umgodi ku-original54.
Sengiphetha, lo msebenzi udalula umphumela we-surface heterogeneity ekugqwaleni kwe-2507 SDSS elungiswe nge-cerium ngokulinganisa okuqukethwe kwamakhemikhali ezingxenyeni ze-nanoscale. Siphendule umbuzo othi kungani insimbi engagqwali igqwala ngisho noma imbozwe ngesendlalelo se-oxide esivikelayo ngokufunda ngobuningi i-microstructure, isimo samakhemikhali sezici ezingaphezulu nokucubungula isignali kusetshenziswa iqoqo le-K-izindlela. Kuye kwatholakala ukuthi iziqhingi ezicebile ze-Fe3+, okuhlanganisa nokuxhumana kwazo kwe-octahedral kanye ne-tetrahedral kuso sonke isakhiwo se-Fe2+/Fe3+ exubile, ziwumthombo wokucekelwa phansi kwefilimu ye-oxide kanye nomthombo wokugqwala kwe-SDSS egoqelwe ngokubanda. I-Nanoislands ebuswa yi-Fe3+ iholela ekungangeni kahle kokugqwala ngisho nalapho kukhona ungqimba olwanele lwe-stoichiometric Cr2O3 passivating. Ngokungeziwe entuthukweni yendlela yokusebenza eyenziwe ekunqumeni umthelela we-nanoscale chemical heterogeneity ekugqwaleni, umsebenzi wamanje kulindeleke ukuthi ugqugquzele izinqubo zobunjiniyela ukuze kuthuthukiswe ukumelana nokugqwala kwezinsimbi ezingenasici ngesikhathi sokwenziwa kwensimbi.
Ukuze kulungiswe ama-ingots e-Ce-2507 SDSS asetshenziswe kulolu cwaningo, izingxenye ezixubile, okuhlanganisa i-Fe-Ce master alloy evalwe ngamashubhu ensimbi ahlanzekile, zancibilika esithandweni sokungenisa imvamisa esiphakathi esingu-150 kg ukuze kukhiqizwe insimbi encibilikisiwe futhi kuthelwe ezibunjeni zokubunjwa. Ukwakheka kwamakhemikhali kukalwa (wt %) kufakwe kuhlu Lokwengeza 2 Ithebula 2. Ingot iqala ukushisa ibe amabhulokhi. Khona-ke insimbi yayifakwe ku-1050 ° C imizuzu engu-60 kwisisombululo esiqinile, bese icinywa emanzini ekamelweni lokushisa. Amasampula ahlolisisiwe acutshungulwa ngokuningiliziwe kusetshenziswa i-TEM ne-DOE ukuze kufundwe izigaba, usayizi wokusanhlamvu kanye ne-morphology. Ulwazi oluthe xaxa mayelana namasampula kanye nenqubo yokukhiqiza lungatholakala kweminye imithombo6,7.
Inqubo yamasampula e-cylindrical (φ10 mm × 15 mm) yokucindezela okushisayo nge-axis ye-cylinder ehambisana nesiqondiso sokuguqulwa kwebhulokhi. Ukucindezelwa kwezinga lokushisa eliphezulu kwenziwa ngesilinganiso sokucindezeleka okuqhubekayo ebangeni lika-0.01-10 s-1 emazingeni okushisa ahlukahlukene ebangeni lika-1000-1150°C kusetshenziswa isifanisi esishisayo se-Gleeble-3800. Ngaphambi kokuguqulwa, amasampula ayeshiswa ezingeni lokushisa elikhethiwe ngesilinganiso esingu-10 °C s-1 imizuzu emi-2 ukuze kuqedwe ukuthamba kwezinga lokushisa. Ngemuva kokuthola ukufana kwezinga lokushisa, amasampuli akhubazeka abe inani langempela le-0.7. Ngemuva kokuguqulwa, kucinywa ngokushesha ngamanzi ukuze kugcinwe isakhiwo esikhubazekile. Khona-ke ama-specimens aqinile ayesikwa ngokuqondana nendawo yokucindezela. Kulolu cwaningo oluthile, sikhethe isifanekiso esonakele ngokushisa ku-1050°C, 10 s-1 ngenxa yokuqina okuncane okubonwa okuphezulu kunezinye izifanekiso7.
Ubuningi (amasampula angu-80 × 10 × 17 mm3) esixazululo esiqinile se-Ce-2507 ahlolwe emshinini wokuguqula ama-roll omabili we-asynchronous we-LG-300 wezigaba ezintathu, onikeze izici zomshini ezihamba phambili phakathi kwawo wonke amanye amakilasi okuguqula6. Izinga lobunzima nokwehliswa kogqinsi kube ngu-0.2 m·s-1 kanye no-5% kumzila ngamunye, ngokulandelana.
Isiteshi sokusebenzela se-Autolab PGSTAT128N sikagesi sasetshenziswa ukukala i-SDSS ngokwe-electrochemically ngemva kokuginqika okubandayo ukuya ku-90% ukuncishiswa kogqinsi (ubunzima obulingana no-1.0 obulinganayo) nokucindezela okushisayo ukuya ku-0.7 uhlobo lwangempela ku-1050 oC kanye no-10 s-1. Indawo yokusebenza ineseli enama-electrode amathathu ane-calomel electrode egcwele njenge-reference electrode, i-graphite counter electrode, kanye nesampula ye-SDSS njenge-electrode esebenzayo. Amasampula asikwa abe amasilinda anobubanzi obungu-11.3 mm, ezinhlangothini lapho izintambo zethusi zazidayiselwe khona. Khona-ke isampula yathelwa nge-epoxy resin, ishiya indawo evulekile yokusebenza engu-1 cm2 njenge-electrode esebenzayo (indawo engezansi yesampula yesilinda). Sebenzisa ukunakekelwa ngesikhathi sokwelashwa kwe-epoxy nangesikhathi sokugcotshwa kwesihlabathi nokupholisha okulandelayo ukuze ugweme ukuqhekeka. Indawo yokusebenza igqitshwa futhi ipholishwe ngokumiswa kokupholishwa kwedayimane ngosayizi wezinhlayiyana ze-micron engu-1, ihlanzwe ngamanzi acwecwe kanye ne-ethanol futhi yomiswe emoyeni obandayo. Ngaphambi kokulinganisa kwe-electrochemical, amasampula aphucuziwe ayevezwa emoyeni izinsuku ezimbalwa ukuze akhe ifilimu yemvelo ye-oxide. Isixazululo esinamanzi se-FeCl3 (6.0 wt.%), esizinziswe nge-HCl kuya ku-pH = 1.0 ± 0.01, sisetshenziselwe ukusheshisa ukugqwala kwensimbi engagqwali55, njengoba sitholakala ezindaweni ezinolaka lapho ama-ion e-chloride ekhona enamandla oksijisi aqinile kanye ne-pH ephansi njengoba kucaciswe yi-ASTM. Amazinga aphakanyisiwe yi-G48 ne-A923. Amasampuli acwiliswa esixazululweni sokuhlola ihora elingu-1 ngaphambi kokuthi kuthathwe noma yiziphi izilinganiso ukuze kufinyelelwe esimweni esiseduze nendawo esimile. Ukuze uthole isixazululo esiqinile, izibonelo ezisebenza ngokushisayo nezigoqelwe ngokubanda, ibanga lemvamisa yokulinganisa i-impedance lalingu-1 × 105 ~ 0.1 Hz, futhi amandla omjikelezo ovulekile (OPS) ayengu-5 mV, okwakungu-0.39, 0.33, no-0.25 VSCE, ngokulandelana. Ukuhlolwa ngakunye kwe-electrochemical kwanoma iyiphi isampuli kwaphindwa okungenani izikhathi ezintathu ngaphansi kwezimo ezifanayo ukuze kuqinisekiswe ukuphinda kukhiqizwe idatha.
Ezilinganisweni ze-HE-SXRD, amabhulokhi ensimbi angama-rectangular duplex angu-1 × 1 × 1.5 mm3 alinganiswa kulayini we-Brockhouse wiggler wamandla aphezulu e-CLS, e-Canada ukuze kulinganiswe ukwakheka kwesigaba56. Ukuqoqwa kwedatha kwenziwa ekamelweni lokushisa ku-Debye-Scherrer geometry noma i-geometry yokuthutha. Ubude begagasi be-X-rays abalinganiswe kusilinganisi se-LaB6 bungu-0.212561 Å, obuhambisana no-58 keV, ephakeme kakhulu kunaleyo ye-Cu Kα (8 keV) evame ukusetshenziswa njengomthombo we-X ray elabhorethri. Isampula ibekwe ebangeni elingama-740 mm ukusuka kumtshina. Ivolumu yokutholwa yesampula ngayinye ngu-0.2 × 0.3 × 1.5 mm3, enqunywa usayizi wohlaka nogqinsi lwesampula. Ngayinye yale datha yaqoqwa kusetshenziswa umtshina wendawo we-Perkin Elmer, umtshina we-X-ray wephaneli eyisicaba, amaphikseli angu-200 µm, 40 × 40 cm2, kusetshenziswa isikhathi sokuchayeka samasekhondi angu-0.3 namafreyimu angu-120.
Izilinganiso ze-X-PEEM zamamodeli amabili akhethiwe zenziwa esiteshini sokugcina se-PEEM somugqa we-Beamline MAXPEEM elabhorethri ye-MAX IV (Lund, Sweden). Amasampula alungiswa ngendlela efanayo neyezilinganiso ze-electrochemical. Amasampula alungisiwe agcinwa emoyeni izinsuku ezimbalwa futhi akhishwa ku-vacuum chamber ye-ultrahigh ngaphambi kokukhanyiswa ngama-synchrotron photon. Ukulungiswa kwamandla kwe-beam kutholakala ngokulinganisa i-spectrum yokuphuma kwe-ion kusuka ku-N 1 s kuya ku-1\(\pi _g^ \st\) yesifunda esivusa amadlingozi nge-hv = 401 eV ku-N2 kanye nokuncika kwamandla we-photon ku-E3/2.57. Ukulingana kwe-Spectral kunikeze i-ΔE (ububanzi bomugqa we-spectral) ~0.3 eV ngaphezu kwebanga lamandla elilinganisiwe. Ngakho-ke, ukulungiswa kwamandla e-beamline kwalinganiselwa ukuthi kube ngu-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-monochromator eguquliwe ye-SX-700 ene-Si 1200-line mm−1 grating ye-Fe 2p L2, Cr32 edge, Cr32 edge L2,3 onqenqemeni, kanye Ce M4,5 onqenqemeni. Ngakho-ke, ukulungiswa kwamandla e-beamline kwalinganiselwa ukuthi kube ngu-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-monochromator eguquliwe ye-SX-700 ene-Si 1200-line mm−1 grating ye-Fe 2p L2.2.3 edge L2.3 L2.3 onqenqemeni, kanye ne-Ce M4.5 onqenqemeni. Таким образом, энергетическое разрешение канала пучка было оценено как E/∆E = 700 эВ/0,3 эВ > 2000 и поток ≈1012 фсок модифицированного монохроматора SX-700 с решеткой Si 1200 штрихов/мм для Fe кромка 2p L2,3, кромка Cr 2p L2,3, кромка Ni 2p L2, 3 ne-Cert. Ngakho-ke, ukulungiswa kwamandla kwesiteshi se-beam kulinganiselwa njenge-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 f/s kusetshenziswa i-monochromator eguquliwe ye-SX-700 ene-Si grating yemigqa engu-1200/mm ye-Fe edge 2p L2, 3p Cr2 edge. kanye ne-Ce edge M4.5.因此，光束线能量分辨率估计為E/ΔE = 700 eV/0.3 eV > 2000 和通量≈1012 ph/s 通过用改进00 1200 线mm−1 光栅用于Fe 2p L2,3 边缘、Cr 2p L2,3 边缘、Ni 2p L2,3 边缘和Ce M4,5 边缘.因此 , 光束线 能量 分辨率 為 為 為 δe = 700 EV/0.3 EV> 2000 和 ≈1012 PH/S 通过 和改进0 的 SX-70 . 1200 线 mm-1 光栅 于 Fe 2P 2P 2P L2.3 边缘、Cr 2p L2.3 边缘、Ni 2p L2.3 边缘和Ce M4.5 边缘.Ngakho-ke, uma usebenzisa i-monochromator ye-SX-700 eguquliwe kanye ne-1200 line Si grating. 3, Cr edge 2p L2.3, Ni edge 2p L2.3 kanye ne-Ce edge M4.5.Nweba amandla e-photon ngezinyathelo ezingu-0.2 eV. Kumandla ngamunye, izithombe ze-PEEM zarekhodwa kusetshenziswa umtshina we-TVIPS F-216 CMOS enoxhumo lwe-fiber optic engu-2 x 2 ehlinzeka ngamaphikseli angu-1024 × 1024 endaweni yokubuka engu-20 µm. Isikhathi sokuchayeka sezithombe amasekhondi angu-0.2, isilinganiso samafreyimu angu-16. Amandla wesithombe se-photoelectron akhethwa ngendlela yokuthi anikeze isignali ye-electron yesibili ephezulu. Zonke izilinganiso zenziwa ngesenzakalo esivamile somugqa we-photon we-polarized. Ukuze uthole ulwazi olwengeziwe ngezilinganiso, bheka ucwaningo lwangaphambilini58. Ngemva kokutadisha inani lemodi yokutholwa kwe-electron (TEY)59 kanye nokusetshenziswa kwayo ku-X-PEEM, ukujula kokutholwa kwale ndlela kulinganiselwa ku-~4–5 nm kusiginali ye-Cr kanye ne-~6 nm yesiginali ye-Fe. Ukujula kwe-Cr kuseduze kakhulu nogqinsi lwefilimu ye-oxide (~4 nm)60,61 kuyilapho ukujula kwe-Fe kukhulu kunogqinsi lwefilimu ye-oxide. I-XAS eqoqwe eduze konqenqema lwe-Fe L iyingxube ye-iron oxide XAS ne-FeO kusukela ku-matrix. Esimweni sokuqala, ukuqina kwama-electron akhishiwe kungenxa yazo zonke izinhlobo zama-electron ezingaba negalelo ku-TEY. Kodwa-ke, isignali yensimbi ehlanzekile idinga amandla e-kinetic aphezulu ukuze ama-electron adlule ungqimba lwe-oxide, afinyelele phezulu, futhi aqoqwe yi-analyzer. Kulokhu, isignali ye-Fe0 ibangelwa ikakhulukazi ama-electron e-LVV Auger nama-electron esibili akhishwa yiwo. Ngaphezu kwalokho, ukuqina kwe-TEY okunikelwe yilawa ma-electron abola phakathi kwendlela yokuphuma kwama-electron49 kunciphisa nakakhulu isiginesha ye-spectral ye-Fe0 kumephu ye-iron XAS.
Ukuhlanganisa ukumbiwa kwedatha kumakhyubhu edatha (idatha ye-X-PEEM) kuyisinyathelo esibalulekile ekukhipheni ulwazi olufanele (izakhiwo zamakhemikhali noma ezibonakalayo) ngendlela ebanzi. Ukuhlanganisa i-K-means kusetshenziswa kabanzi ezindaweni ezimbalwa, okuhlanganisa ukubona komshini, ukucutshungulwa kwesithombe, ukuqashelwa kwephethini okungagadiwe, ubuhlakani bokwenziwa, nokuhlaziya ngokwezigaba24. Isibonelo, i-K-means clustering isetshenziswa kahle ekuhlanganiseni idatha yesithombe se-hyperspectral62. Empeleni, ngedatha yezinto eziningi, i-algorithm ye-K-means ingaziqoqa kalula ngokuya ngolwazi mayelana nezimfanelo zazo (izici zamandla e-photon). I-K-means clustering i-algorithm ephindaphindayo yokuhlukanisa idatha ibe ngamaqembu angu-K angagqagqani (amaqoqo), lapho iphikseli ngayinye ingeyeqoqo elithile kuye ngokusatshalaliswa kwendawo kwe-chemical inhomogeneity ekwakhekeni kwesakhiwo sensimbi esincane. I-algorithm ye-K-means iqukethe izinyathelo ezimbili: isinyathelo sokuqala sibala amasentimitha angu-K, futhi isinyathelo sesibili sinikeza iphuzu ngalinye kuqoqo elinamacentroid angomakhelwane. Isikhungo se-gravity yeqoqo sichazwa njenge-arithmetic mean yamaphoyinti edatha (i-XAS spectra) yalelo qoqo. Kunamabanga ahlukene okuchaza ama-centroid angomakhelwane njengamabanga e-Euclidean. Ukuze uthole isithombe esifakiwe sika-px,y (x kanye no-y anokulungiswa ngamaphikseli), i-CK iyisikhungo samandla adonsela phansi eqoqo; lesi sithombe singabe sesihlukaniswa (sihlanganiswe) sibe amaqoqo angu-K kusetshenziswa i-K-means63. Izinyathelo zokugcina ze-algorithm ye-K-means clustering yilezi:
Isinyathelo sesi-2. Bala izinga lobulungu bawo wonke amaphikseli ngokuya nge-centroid yamanje. Isibonelo, ibalwa ukusuka ku-Euclidean ibanga d phakathi kwesikhungo nephikseli ngayinye:
Isinyathelo sesi-3 Yabela iphikseli ngayinye ku-centroid eseduze. Bese ubala kabusha izindawo ze-K centroid kanje:
Isinyathelo sesi-4. Phinda inqubo (izibalo (7) kanye (8)) kuze kuhlangane amasentimitha. Imiphumela yokugcina yekhwalithi yeqoqo ihlotshaniswa kakhulu nokukhetha okuhle kwama-centroids63 okuqala. Okwesakhiwo sedatha ye-PEEM yezithombe zensimbi, ngokuvamile u-X (x × y × λ) iyikhyubhu yedatha yamalungu afanayo angu-3D, kuyilapho ama-eksisi angu-x kanye no-y amelela ulwazi lwendawo (ukulungiswa kwephikiseli) kanye ne-axis ethi λ ihambisana nemodi ye-spectral yamandla yamafotoni . I-algorithm ye-K-means yasetshenziselwa ukuhlola izifunda zentshisakalo kudatha ye-X-PEEM ngokuhlukanisa amaphikseli (amaqoqo noma amabhlogo angaphansi) ngokuya ngezici zawo ze-spectral futhi kukhishwe i-centroid ehamba phambili (i-XAS spectral curve) yomhlaziyi ngamunye (iqoqo). Isetshenziselwa ukutadisha ukusatshalaliswa kwendawo, izinguquko ze-spectral zendawo, ukuziphatha kwe-oxidation kanye nesimo samakhemikhali. Isibonelo, i-algorithm yokuhlanganisa ye-K-means yasetshenziswa ezifundeni ze-Fe L-edge kanye ne-Cr L-edge endaweni esebenza ngokushisayo negoqelwe ngokubanda i-X-PEEM. Izinombolo ezihlukahlukene zamaqoqo e-K (izifunda ezincane) zahlolwa ukuze kutholwe amaqoqo nama-centroid angcono kakhulu. Uma igrafu iboniswa, amaphikseli anikezwa kabusha kuma-centroid eqoqo alungile. Ukusabalalisa kombala ngakunye kuhambisana nendawo emaphakathi yeqoqo, okubonisa ukuhlelwa kwendawo kwezinto zamakhemikhali noma ezibonakalayo. Ama-centroids akhishiwe ayinhlanganisela yomugqa ye-spectra ehlanzekile.
Idatha esekela imiphumela yalolu cwaningo iyatholakala kumbhali ofanele we-WC uma kunesicelo esifanele.
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