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Insimbi engagqwali esetshenziswa kabanzi kanye nezinguqulo zayo ezenziwe ngayo ziyamelana nokugqwala ezimweni ezizungezile ngenxa yengqimba yokungaphazamisi equkethe i-chromium oxide. Ukugqwala nokuguguleka kwensimbi kuvame ukuhlotshaniswa nokubhujiswa kwalezi zingqimba, kodwa akuvamile ukubonakala kokungalingani kobuso, kuye ngezinga le-microscopic. Kulo msebenzi, ukungafani kobuso bamakhemikhali e-nanoscale, okutholwe nge-spectroscopic microscopy kanye nokuhlaziywa kwe-chemometric, kubusa ngokungalindelekile ukuqhekeka nokugqwala kwensimbi engagqwali e-cold rolled cerium modified super duplex stainless steel 2507 (SDSS) ngesikhathi sokuguqulwa kwayo okushisayo. Nakuba i-X-ray photoelectron microscopy ibonise ukumbozwa okufanayo kwengqimba yemvelo ye-Cr2O3, ukusebenza kokungaphazamisi kwe-cold rolled SDSS kwakukubi ngenxa yokusatshalaliswa kwendawo kweziqhingi ezicebile ze-Fe3+ kungqimba lwe-oxide ye-Fe/Cr. Lolu lwazi lwesikali se-athomu lunikeza ukuqonda okujulile kokugqwala kwensimbi engagqwali futhi kulindeleke ukuthi kusize ekulweni nokugqwala kwezinsimbi ezifanayo ezine-alloy ephezulu.
Kusukela kwasungulwa insimbi engagqwali, izakhiwo zokulwa nokugqwala ze-ferrochrome ziye zahlotshaniswa ne-chromium, eyakha ama-oxide/oxyhydroxide aqinile futhi ibonisa ukuziphatha okungenamsebenzi ezindaweni eziningi. Uma kuqhathaniswa nezinsimbi ezivamile (i-austenitic ne-ferritic) ezingagqwali i-1, 2, 3, izinsimbi eziqinile eziqinile (i-SDSS) zinokumelana nokugqwala okungcono kanye nezakhiwo ezinhle kakhulu zemishini. Amandla akhuphukile emishini avumela imiklamo elula futhi emincane kakhulu. Ngokuphambene nalokho, i-SDSS engabizi inokumelana okuphezulu nokugqwala kwemigodi kanye ne-crevice, okuholela empilweni yesevisi ende, ngaleyo ndlela yandisa ukusetshenziswa kwayo ekulawuleni ukungcola, ezitsheni zamakhemikhali, kanye nasembonini kawoyela negesi ogwini lolwandle4. Kodwa-ke, ububanzi obuncane bamazinga okushisa okwelashwa kokushisa kanye nokwakheka okubi kuvimbela ukusetshenziswa kwazo okubanzi okusebenzayo. Ngakho-ke, i-SDSS iguqulwa ukuze kuthuthukiswe ukusebenza okungenhla. Isibonelo, ukuguqulwa kwe-Ce kwethulwa ku-SDSS 2507 (Ce-2507) ngokuqukethwe okuphezulu kwe-nitrogen6,7,8. I-rare earth element (Ce) ekugxilweni okufanele okungu-0.08 wt.% inomphumela omuhle ezimpahleni zemishini ze-DSS, njengoba ithuthukisa ukuhluzwa kokusanhlamvu kanye namandla omngcele wokusanhlamvu. Ukumelana nokuguguleka nokugqwala, amandla okuthambekela kanye namandla okukhiqiza, kanye nokusebenza okushisa nakho kuyathuthuka9. Inani elikhulu le-nitrogen lingathatha indawo yokuqukethwe kwe-nickel okubizayo, okwenza i-SDSS ibe ngcono kakhulu10.
Muva nje, i-SDSS iguqulwe ngepulasitiki emazingeni okushisa ahlukahlukene (i-cryogenic, ebandayo neshisayo) ukuze kufezwe izakhiwo ezinhle kakhulu zemishini6,7,8. Kodwa-ke, ukumelana okuhle kakhulu kokugqwala kwe-SDSS ngenxa yokuba khona kwefilimu encane ye-oxide ebusweni kuthinteka yizici eziningi ezifana nokungafani okungokwemvelo ngenxa yokuba khona kwezigaba ezingafani ezinemingcele ehlukene yokusanhlamvu, ukwehla okungafuneki kanye nokusabela okuhlukile. ukuguquguquka kwezigaba ze-austenitic ne-ferritic7. Ngakho-ke, ukutadisha izakhiwo zesizinda ezincane zamafilimu anjalo kuze kufike ezingeni lesakhiwo se-elekthronikhi kuba yinto ebalulekile ekuqondeni ukugqwala kwe-SDSS futhi kudinga amasu okuhlola ayinkimbinkimbi. Kuze kube manje, izindlela ezizwela ubuso 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 zobuso. izimo zamakhemikhali zento efanayo ezindaweni ezahlukene zesikhala se-nanoscale. Izifundo eziningana zakamuva zihlobanise ukushiswa kwe-chromium endaweni ethile nokuziphatha kokushiswa okubonwe kwezinsimbi ezingagqwali ze-austenitic17, izinsimbi ze-martensitic18 kanye ne-SDSS19,20. Kodwa-ke, lezi zifundo zigxile kakhulu emthonjeni we-Cr heterogeneity (isb., isimo se-Cr3+ oxidation) ekuphikisweni kokushiswa. Ukungafani kwe-lateral ezimweni ze-oxidation zezinto kungabangelwa ama-compound ahlukene anezakhi ezifanayo, njenge-iron oxides. La ma-compound, azuze usayizi omncane ngenxa yokwelashwa kwe-thermomechanical, asondelene kakhulu, kodwa ahlukile ngokwakheka kanye nesimo se-oxidation16,21. Ngakho-ke, ukuze kutholakale ukuqhekeka kwamafilimu e-oxide kanye nokufakwa kwemigodi okulandelayo, kubalulekile ukuqonda ukungafani kwendawo ezingeni le-microscopic. Naphezu kwalezi zidingo, izilinganiso zokulinganisa ezifana nokungafani kwe-lateral ku-oxidation, ikakhulukazi i-Fe esikalini se-nano- kanye ne-atomic, kusantuleka, futhi ukuhlangana kwayo nokumelana nokushiswa kusalokhu kungahlolwa. Kuze kube muva nje, isimo samakhemikhali sezinto ezahlukahlukene, njenge-Fe ne-Ca22, kumasampula ensimbi sasichazwa ngobuningi kusetshenziswa i-soft X-ray photoelectron microscopy (X-PEEM) ezindaweni zokukhishwa kwemisebe ye-synchrotron ye-nanoscale. Kuhlanganiswe ne-X-ray absorption spectroscopy (XAS) ezwela amakhemikhali, i-X-PEEM ivumela ukulinganiswa kwe-XAS ngesisombululo esiphezulu sendawo kanye ne-spectral, ihlinzeka ngolwazi lwamakhemikhali mayelana nokwakheka kwezinto kanye nesimo sazo samakhemikhali ngesisombululo sendawo esifinyelela esikalini sama-nanometer angamashumi amabili nantathu. . Lokhu kubonwa kwe-spectromicroscopic kokuqala kwenza kube lula ukubonwa kwamakhemikhali endawo futhi kungabonisa izinguquko zamakhemikhali esikhaleni sengqimba yensimbi ezingakaze zihlolwe ngaphambilini.
Lolu cwaningo lwandisa izinzuzo ze-PEEM ekutholeni umehluko wamakhemikhali ku-nanoscale futhi luveza indlela yokuhlaziya ubuso be-athomu eqondakalayo yokuqonda ukuziphatha kokugqwala kwe-Ce-2507. Lusebenzisa indlela ye-K-means24 chemometric ehlanganisiwe ukuze kuhlolwe ukulingana kwamakhemikhali omhlaba wonke (hetero) kwezinto ezihilelekile, izimo zawo zamakhemikhali ezivezwe ngendlela yezibalo. Ngokungafani nokugqwala okuqalwe ukubhujiswa kwefilimu ye-chromium oxide esimweni sendabuko, ukungasebenzi kahle kanye nokumelana nokugqwala okuphansi okwamanje kubangelwa yiziqhingi ze-nanois ezicebile ze-Fe3+ eduze kwengqimba ye-oxide ye-Fe/Cr, ezingaba yizakhiwo zokuvikela. I-oxide ibhubhisa ifilimu enamachashazi futhi ibangele ukugqwala.
Ukuziphatha okulimazayo kwe-SDSS 2507 okukhubazekile kwahlolwa okokuqala kusetshenziswa izilinganiso ze-electrochemical. Ku-Fig. Isithombe 1 sibonisa ama-Nyquist kanye nama-Bode curves amasampula akhethiwe kusisombululo samanzi esi-acidic (pH = 1) se-FeCl3 ekushiseni kwegumbi. I-electrolyte ekhethiwe isebenza njenge-ejenti enamandla yokuxilisa, echaza ukuthambekela kwefilimu yokudlula ekuqhekekeni. Nakuba izinto zingazange zidlule ekufakweni okuzinzile ekushiseni kwegumbi, ukuhlaziywa kunikeze ukuqonda ngezenzakalo ezingase zenzeke kanye nokugqwala okulandelayo. Isekethe efanayo (Isithombe 1d) yasetshenziswa ukulingana ne-spectroscopy ye-electrochemical impedance (EIS), futhi imiphumela yokufaneleka ehambisanayo iboniswe kuThebula 1. Ama-semicircle angaphelele avela kumasampula aphathwe ngesisombululo kanye nasebenza ngokushisa, kuyilapho ama-semicircle acindezelwe avela kuma-counterparts aqoqwe ngokubandayo (Isithombe .1b). Ku-EIS spectroscopy, i-radius ye-semicircle ingabhekwa njengokumelana kwe-polarization (Rp)25,26. I-Rp yendlela yokugijima ephathwe ngesisombululo kuThebula 1 icishe ibe ngu-135 kΩ cm–2, noma kunjalo, amanani endlela yokugijima yendlela yokugijima esebenza ngokushisa kanye ne-cold-rolled aphansi kakhulu, angu-34.7 kanye no-2.1 kΩ cm–2, ngokulandelana. Lokhu kwehla okuphawulekayo ku-Rp kubonisa umphumela omubi wokuguqulwa kwepulasitiki ekungangeni nasekumelaneni nokugqwala, njengoba kuboniswe emibikweni yangaphambilini27,28,29,30.
a Nyquist, b, c I-Bode impedance kanye ne-phase diagrams, kanye namamodeli wesekethe alinganayo ahambisanayo d, lapho i-RS ingukumelana kwe-electrolyte, i-Rp ingukumelana kwe-polarization, kanye ne-QCPE iyi-oxide ye-constant phase element esetshenziswa ukulingisa i-capacitance engeyona i-ideal (n). Izilinganiso ze-EIS zenziwa ku-open circuit potential.
Ama-constant ahambisanayo aboniswa ku-Bode plot, kanye ne-plateau ebangeni eliphezulu lama-frequency elimele ukumelana kwe-electrolyte RS26. Njengoba imvamisa yehla, i-impedance iyanda futhi kutholakala i-negative phase angle, okubonisa ukubusa kwe-capacitance. I-phase angle iyanda, igcina i-maximum phezu kwebanga lama-frequency elibanzi, bese iyancipha (Isithombe 1c). Kodwa-ke, kuzo zonke izimo ezintathu, lokhu okuphezulu kusengaphansi kuka-90°, okubonisa ukuziphatha kwe-capacitive okungekuhle ngenxa yokusabalala kwe-capacitive. Ngakho-ke, i-QCPE constant phase element (CPE) isetshenziselwa ukumela ukusatshalaliswa kwe-interfacial capacitance okuvela ebulukhunini bomphezulu noma ukungalingani, ikakhulukazi esikalini se-athomu, i-fractal geometry, i-electrode porosity, i-non-uniform potential, kanye ne-geometry ngesimo sama-electrode31,32. I-CPE impedance:
lapho u-j eyinombolo ecatshangelwayo kanti u-ω iyimvamisa ye-angular. I-QCPE iyi-constant ezimele imvamisa ehambisana nendawo evulekile esebenzayo ye-electrolyte. i-n iyinombolo yamandla engenakulinganiswa echaza ukuphambuka kwe-capacitor kusuka ku-capacitance efanelekile, okungukuthi uma u-n eseduze no-1, i-CPE iseduze kakhulu ne-capacitive kuphela, kuyilapho uma u-n eseduze no-zero, ibonakala iphikisana. Ukuphambuka okuncane kuka-n, eduze no-1, kubonisa ukuziphatha kwe-capacitive okungeyona i-ideal kwendawo ngemuva kokuhlolwa kwe-polarization. I-QCPE ye-cold rolled SDSS iphakeme kakhulu kunezinye zayo, okusho ukuthi ikhwalithi yendawo ayifani kangako.
Ngokuhambisana nezakhiwo eziningi zokumelana nokugqwala kwezinsimbi ezingagqwali, okuqukethwe okuphezulu kwe-Cr kwe-SDSS ngokuvamile kuphumela ekumelaneni okuhle kakhulu kokugqwala kwe-SDSS ngenxa yokuba khona kwefilimu ye-oxide evikelayo edlulayo ebusweni17. Amafilimu anjalo adlulayo avame ukucebile ngama-oxide e-Cr3+ kanye/noma ama-hydroxide, ikakhulukazi ngokuhlanganiswa nama-oxide e-Fe2+, ama-Fe3+ kanye/noma (oxy)33. Naphezu kokufana okufanayo kobuso, ungqimba lwe-oxide edlulayo, kanye nokuqhekeka kobuso okubonwe ngokwezilinganiso ezincane6,7, ukuziphatha kokugqwala kwe-SDSS esebenza ngokushisa kanye ne-cold-rolled kuhlukile, ngakho-ke ucwaningo olujulile lwezici zesakhiwo luyadingeka ukuze kuguqulwe insimbi.
Isakhiwo esincane sensimbi engagqwali esiguquliwe safundwa ngobuningi kusetshenziswa ama-X-ray angaphakathi kanye nama-synchrotron anamandla aphezulu (Izithombe Ezingeziwe 1, 2). Ukuhlaziywa okuningiliziwe kunikezwe kulwazi olungeziwe. Nakuba kukhona ukuvumelana okuvamile ngohlobo lwesigaba esikhulu, umehluko kuma-fraction esigaba esikhulu utholakale, abhalwe kuThebula Elingeziwe 1. Lokhu kungafani kungase kubangelwe ama-fraction esigaba angalingani ebusweni kanye nasevolumu, athintwa ukujula kokuthola okuhlukile kwe-X-ray diffraction (XRD). ) nemithombo yamandla ehlukene yama-photon esigameko 34. Ama-fraction e-austenite aphezulu kakhulu kuma-specimens aqoqwe abandayo anqunywe yi-XRD emthonjeni welabhorethri abonisa ukudlula okungcono bese kuba ukumelana nokugqwala okungcono 35, kuyilapho imiphumela enembile kakhulu neyezibalo iphakamisa ukuthambekela okuphambene kuma-fraction esigaba. Ngaphezu kwalokho, ukumelana nokugqwala kwensimbi nakho kuncike ezingeni lokucwengwa kokusanhlamvu, ukunciphisa usayizi wokusanhlamvu, ukwanda kokuguquguquka okuncane kanye nobuningi bokuhlukaniswa okwenzeka ngesikhathi sokwelashwa kwe-thermomechanical 36,37,38. Amasampula asebenza ngokushisa abonise uhlobo olunezinhlayiya eziningi, olubonisa okusanhlayiya okusanhlayiya okusanhlayiya okusanhlayiya, kuyilapho amasongo abushelelezi abonwe kumasampula aqoqwe ngokubandayo (Isithombe Esingeziwe 3) ayebonisa ukucwengwa okukhulu kokusanhlayiya ukuze kube nosayizi omncane emsebenzini wangaphambilini. Lokhu kufanele kuthande ukwakheka kwefilimu engasebenzi kanye nokwanda kokumelana nokugqwala. Ubuningi obukhulu bokuhlukaniswa kwezicubu buvame ukuhlotshaniswa nokumelana okuphansi kokufakwa kwezicubu, okuhambisana kahle nokulinganiswa kwe-electrochemical.
Izinguquko esimweni samakhemikhali sama-microdomains ezinto eziyinhloko zafundwa ngokuhlelekile kusetshenziswa i-X-PEEM. Nakuba kunezinye izinto ezixubayo, i-Cr, i-Fe, i-Ni kanye ne-Ce39 zikhethiwe lapha, njengoba i-Cr iyisici esiyinhloko sokwenza ifilimu engasebenzi, i-Fe iyisici esiyinhloko sensimbi, kanti i-Ni ithuthukisa ukudlula futhi ilinganisela isigaba se-ferrite-austenitic. Isakhiwo nokuguqulwa kuyinhloso ye-Ce. Ngokulungisa amandla omsebe we-synchrotron, i-XAS yabamba izici eziyinhloko ze-Cr (umphetho we-L2.3), i-Fe (umphetho we-L2.3), i-Ni (umphetho we-L2.3), kanye ne-Ce (umphetho we-M4.5) ebusweni. -2507 SDSS. Ukuhlaziywa kwedatha okufanele kwenziwe ngokufaka ukulinganiswa kwamandla ngedatha eshicilelwe (isb. i-XAS ku-Fe L2, izimbambo ezi-340,41).
Ku-Fig. Isithombe 2 sibonisa izithombe ze-X-PEEM ze-hot-worked (Isithombe 2a) kanye ne-cold-rolled (Isithombe 2d) Ce-2507 SDSS kanye ne-XAS Cr kanye ne-Fe L2,3 edges ezihambisanayo ezindaweni ezimakwe ngazinye. Unqenqema lwe-L2,3 XAS luhlola izimo ze-3d ezingenamuntu zama-electron ngemva kokukhipha i-photoexcitation emazingeni okuhlukana kwe-2p3/2 (L3 edge) kanye ne-2p1/2 (L2 edge) spin-orbit. Ulwazi mayelana nesimo se-valence se-Cr lutholakale ekuhlaziyweni kwe-X-ray diffraction konqenqema lwe-L2,3 ku-Fig. 2b,d. Ukuqhathaniswa kwesixhumanisi. 42, 43 kubonise ukuthi iziqongo ezine u-A (578.3 eV), u-B (579.5 eV), u-C (580.4 eV), kanye no-D (582.2 eV) zibonwe eduze konqenqema lwe-L3, zibonisa ama-ion e-octahedral Cr3+, i-Cr2O3 ehambisanayo. Ama-spectra okuhlola ayavumelana nezibalo zethiyori, njengoba kuboniswe kumaphaneli b no-e, atholwe ekubalweni kwensimu yekristalu eminingi esibonakalayo se-Cr L2.3 kusetshenziswa insimu yekristalu engu-2.0 eV44. Zombili izindawo ze-SDSS ezishisiwe kanye nezigoqiwe ezibandayo zimbozwe ngesendlalelo esifanayo se-Cr2O3.
Isithombe esishisayo se-X-PEEM SDSS esakhiwe ngokushisa esihambisana nomphetho b Cr L2.3 kanye nomphetho c Fe L2.3, d Isithombe esishisayo X-PEEM se-SDSS egoqekile ebandayo esihambisana nomphetho e Cr L2.3 kanye f Fe L2.3 ohlangothini (e). Ama-spectra e-XAS adwetshwe ezindaweni ezahlukahlukene zesikhala ezimakwe ezithombeni ezishisayo (a, d) ngemigqa ephuzi enamachashazi ku-(b) kanye no-(e) amele ama-spectra e-XAS alingisiwe e-Cr3+ anenani lensimu yekristalu elingu-2.0 eV. Ezithombeni ze-X-PEEM, kusetshenziselwa iphalethi yokushisa ukuthuthukisa ukufundwa kwesithombe, lapho imibala kusukela kokuluhlaza okwesibhakabhaka kuya kokubomvu ilingana nobukhulu bokumuncwa kwe-X-ray (kusukela phansi kuya phezulu).
Kungakhathaliseki ukuthi lezi zinto zensimbi zinjani, isimo samakhemikhali sokwengezwa kwezinto ze-Ni ne-Ce alloying kuzo zombili izibonelo sahlala sinjalo. Umdwebo owengeziwe. Ku-fig. 5-9 kukhombisa izithombe ze-X-PEEM kanye nama-spectra e-XAS ahambisanayo e-Ni ne-Ce ezindaweni ezahlukahlukene ebusweni bezibonelo ezishisiwe neziqoqiwe. I-Ni XAS ikhombisa isimo se-oxidation se-Ni2+ phezu kobuso bonke obulinganisiwe bezibonelo ezishisiwe neziqoqiwe (Ingxoxo Engeziwe). Kuyaphawuleka ukuthi endabeni yezibonelo ezishisiwe, isignali ye-XAS ye-Ce ayibonwa, kuyilapho i-spectrum ye-Ce3+ yezibonelo eziqoqiwe ezibandayo ibonwa ngesikhathi esisodwa. Ukubonwa kwamabala e-Ce kumasampula aqoqiwe abandayo kubonise ukuthi i-Ce ikhona ikakhulukazi ngesimo se-precipitates.
Ku-SDSS eguquliwe ngokushisa, akukho shintsho lwesakhiwo sendawo ku-XAS olubonwe emaphethelweni e-Fe L2.3 (Isithombe 2c). Kodwa-ke, njengoba kuboniswe ku-Fig. 2f, i-Fe matrix ishintsha isimo sayo samakhemikhali ngama-microscope ngamaphuzu ayisikhombisa akhethwe ngokungahleliwe ku-SDSS egoqekile ebandayo. Ngaphezu kwalokho, ukuze kutholakale umbono onembile wezinguquko esimweni se-Fe ezindaweni ezikhethiwe ku-Fig. 2f, kwenziwa izifundo zobuso bendawo (Isithombe 3 kanye nesithombe esengeziwe 10) lapho kwakhethwa khona izifunda ezincane eziyindilinga. Ama-spectra e-XAS onqenqemeni lwe-Fe L2,3 lwezinhlelo ze-α-Fe2O3 kanye nama-octahedral oxide e-Fe2+ aklanywe kusetshenziswa izibalo zensimu yekristalu ehlukahlukene kusetshenziswa amasimu ekristalu angu-1.0 (Fe2+) kanye no-1.0 (Fe3+)44. Siphawula ukuthi i-α-Fe2O3 kanye ne-γ-Fe2O3 zine-symmetries yendawo ehlukile45,46, i-Fe3O4 inenhlanganisela ye-Fe2+ kanye ne-Fe3+,47, kanye ne-FeO45 njenge-Fe2+ oxide ehlukanisiwe ngokusemthethweni (3d6). Siphawula ukuthi i-α-Fe2O3 kanye ne-γ-Fe2O3 zine-symmetries yendawo ehlukile45,46, i-Fe3O4 inenhlanganisela ye-Fe2+ kanye ne-Fe3+,47, kanye ne-FeO45 njenge-Fe2+ oxide ehlukanisiwe ngokusemthethweni (3d6).Qaphela ukuthi i-α-Fe2O3 kanye ne-γ-Fe2O3 zine-symmetries yendawo ehlukile45,46, i-Fe3O4 ihlanganisa i-Fe2+ kanye ne-Fe3+,47 kanye ne-FeO45 ngesimo se-oxide ehlukanisiwe ngokomthetho i-Fe2+ (3d6).Qaphela ukuthi i-α-Fe2O3 kanye ne-γ-Fe2O3 zine-symmetries yendawo ehlukene45,46, i-Fe3O4 inezinhlanganisela ze-Fe2+ kanye ne-Fe3+,47 kanti i-FeO45 isebenza njenge-oxide ye-Fe2+ ehlukanisiwe esemthethweni (3d6). Wonke ama-ion e-Fe3+ ku-α-Fe2O3 anezikhundla ze-Oh kuphela, kuyilapho i-γ-Fe2O3 ivame ukuvezwa njenge-Fe3+ t2g [Fe3+5/3V1/3]eg O4 spinel enezikhala ezikhundleni zesib. Ngakho-ke, ama-ion e-Fe3+ ku-γ-Fe2O3 anezikhundla ze-Td kanye ne-Oh. Njengoba kushiwo emsebenzini odlule, yize izilinganiso zokuqina zalezi ezimbili zihlukile, isilinganiso sazo sokuqina isib/t2g singu-≈1, kanti kulokhu isilinganiso sokuqina esibonwe isib/t2g singu-1. Lokhu kuqeda amathuba okuba kube yi-Fe3+ kuphela kulesi simo. Uma sibheka isimo se-Fe3O4 kanye nenhlanganisela ye-Fe2+ kanye ne-Fe3+, kwaziwa ukuthi isici sokuqala esibuthakathaka (esinamandla) emphethweni we-L3 we-Fe sibonisa ukungabi bikho kwabantu okuncane (okukhulu) esimweni se-t2g. Lokhu kusebenza ku-Fe2+ (Fe3+), okubonisa ukwanda kwesibonakaliso sokuqala esibonisa ukwanda kokuqukethwe kwe-Fe2+47. Le miphumela ikhombisa ukuthi i-Fe2+ kanye ne-γ-Fe2O3, i-α-Fe2O3 kanye/noma i-Fe3O4 zibusa ezindaweni ezibandayo ezigoqekile zezinhlanganisela.
Izithombe ezikhulisiwe ze-photoemission electron thermal ze-(a, c) kanye ne-(b, d) XAS spectra ngaphesheya komphetho we-Fe L2,3 ezindaweni ezahlukahlukene zesikhala ngaphakathi kwezifunda ezikhethiwe 2 kanye ne-E ku-Figs. 2d.
Idatha yokuhlola etholakele (Isithombe 4a kanye nesithombe esengeziwe 11) yadwetshwa futhi yaqhathaniswa naleyo yama-compound amsulwa 40, 41, 48. Ngokuyisisekelo, izinhlobo ezintathu ezahlukene zama-spectra e-Fe L-edge XAS abonwe ngokuhlola (XAS-1, XAS-2 kanye ne-XAS-3: Isithombe 4a) zabonwa ezindaweni ezahlukene ngokwendawo. Ikakhulukazi, i-spectrum efana ne-2-a (ekhonjiswe njenge-XAS-1) ku-Fig. 3b yabonwa kuso sonke isifunda esithakazelisayo, yalandelwa i-spectrum engu-2-b (ebhalwe nge-XAS-2), kuyilapho i-spectrum efana ne-E-3 yabonwa ku-Fig. 3d (ebizwa ngokuthi i-XAS-3) yabonwa ezindaweni ezithile ezisendaweni. Ngokuvamile, amapharamitha amane asetshenziswa ukuhlonza izimo ze-valence ezikhona kusampula ye-probe: (1) izici ze-spectral ze-L3 kanye ne-L2, (2) izikhundla zamandla zezici ze-L3 kanye ne-L2, (3) umehluko wamandla we-L3-L2, (4) isilinganiso sokuqina kwe-L2 /L3. Ngokusho kokubonwa okubonakalayo (Umfanekiso 4a), zonke izingxenye ezintathu ze-Fe, okungukuthi i-Fe0, i-Fe2+, kanye ne-Fe3+, zikhona ebusweni be-SDSS efundwe. Isilinganiso sokuqina esibaliwe i-L2/L3 siphinde sabonisa ukuba khona kwazo zonke izingxenye ezintathu.
a Kubonwe idatha emithathu eyahlukene yokuhlola (imigqa eqinile i-XAS-1, i-XAS-2 kanye ne-XAS-3 ihambelana ne-2-a, i-2-b kanye ne-E-3 ku-Fig. 2 kanye ne-Fig. 3) uma kuqhathaniswa ne-XAS elingisiwe Ukuqhathanisa ama-spectra, ama-octahedron Fe2+, i-Fe3+, amanani ensimu yekristalu angu-1.0 eV kanye ne-1.5 eV, ngokulandelana, b–d Kulinganiswe idatha yokuhlola (i-XAS-1, i-XAS-2, i-XAS-3) kanye nedatha ye-LCF elungiselelwe ehambisanayo (umugqa omnyama oqinile), kanye nokuqhathanisa ama-spectra e-XAS-3 ne-Fe3O4 (isimo esixubile se-Fe) kanye nezindinganiso ze-Fe2O3 (i-Fe3+ emsulwa).
Kusetshenziswe ukulingana kwenhlanganisela eqondile (LCF) yamazinga amathathu40,41,48 ukuze kulinganiswe ukwakheka kwe-iron oxide. I-LCF yasetshenziswa kuma-spectra amathathu akhethiwe e-Fe L-edge XAS abonisa umehluko omkhulu, okungukuthi i-XAS-1, i-XAS-2 kanye ne-XAS-3, njengoba kuboniswe ku-Fig. 4b–d. Ngokufakwa kwe-LCF, i-10% Fe0 yacatshangelwa kuzo zonke izimo ngenxa ye-ledge encane esiyibonile kuyo yonke idatha kanye neqiniso lokuthi insimbi yensimbi iyisakhi esiyinhloko sensimbi. Ngempela, ukujula kokuhlolwa kwe-X-PEEM ye-Fe (~6 nm)49 kukhulu kunobukhulu bengqimba ye-oxidation elinganisiwe (kancane > 4 nm), okuvumela ukutholakala kwesiginali evela ku-iron matrix (Fe0) ngaphansi kwengqimba ye-passivation. Ngempela, ukujula kokuhlolwa kwe-X-PEEM ye-Fe (~6 nm)49 kukhulu kunobukhulu bengqimba ye-oxidation elinganisiwe (kancane > 4 nm), okuvumela ukutholakala kwesiginali evela ku-iron matrix (Fe0) ngaphansi kwengqimba ye-passivation. 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 kunobukhulu obucatshangelwe bengqimba ye-oxidation (kancane >4 nm), okwenza kube nokwenzeka ukuthola isignali evela ku-iron matrix (Fe0) ngaphansi kwengqimba ye-passivation.Eqinisweni, i-X-PEEM ithola i-Fe (~6 nm)49 ejulile kunobukhulu obulindelekile bengqimba ye-oxide (ngaphezu nje kwe-4 nm), okuvumela ukutholakala kwezibonakaliso ezivela ku-iron matrix (Fe0) ngaphansi kwengqimba ye-passivation. Ukuhlanganiswa okuhlukahlukene kwe-Fe2+ ne-Fe3+ kwenziwa ukuze kutholakale ikhambi elingcono kakhulu ledatha yokuhlola ebonwe. Ku-Fig. Umfanekiso 4b ukhombisa ukuhlanganiswa kwe-Fe2+ ne-Fe3+ ku-XAS-1 spectrum, lapho izilinganiso ze-Fe2+ ne-Fe3+ ziseduze, cishe ngo-45%, okubonisa isimo se-oxidation esixubile se-Fe. Kanti ku-XAS-2 spectrum, iphesenti le-Fe2+ ne-Fe3+ liba ngu-~30% no-60%, ngokulandelana. Okuqukethwe kwe-Fe2+ kuphansi kunokwe-Fe3+. Isilinganiso se-Fe2+ ne-Fe3 esingu-1:2 sisho ukuthi i-Fe3O4 ingakhiwa ngesilinganiso esifanayo sama-ion e-Fe. Ngaphezu kwalokho, ku-XAS-3 spectrum, amaphesenti e-Fe2+ kanye ne-Fe3+ ashintshele ku-~10% kanye no-80%, okubonisa ukuguqulwa okuphezulu kwe-Fe2+ kuya ku-Fe3+. Njengoba kushiwo ngenhla, i-Fe3+ ingavela ku-α-Fe2O3, γ-Fe2O3 noma i-Fe3O4. Ukuze uqonde umthombo ongaba khona we-Fe3+, ama-XAS-3 spectra adwetshwe kanye nezindinganiso ezahlukene ze-Fe3+ ku-Fig. 4e ezibonisa ukufana nazo zonke izindinganiso ezimbili lapho kucatshangelwa i-Peak B. Kodwa-ke, ukuqina kwehlombe (A: kusuka ku-Fe2+) kanye nesilinganiso sokuqina kwe-B/A kubonisa ukuthi i-spectrum ye-XAS-3 iseduze kodwa ayifani neka-γ-Fe2O3. Uma kuqhathaniswa ne-bulk γ-Fe2O3, ukuqina kwe-Fe 2p XAS kwe-A SDSS peak kuphakeme kancane (Fig. 4e), okubonisa ukuqina kwe-Fe2+ okuphezulu. Nakuba i-spectrum ye-XAS-3 ifana neye-γ-Fe2O3, lapho i-Fe3+ ikhona khona kuzo zombili izikhundla ze-Oh ne-Td, ukuhlonza izimo ze-valence ezahlukene kanye nokuhlanganiswa kuphela ngomphetho we-L2,3 noma isilinganiso sokuqina kwe-L2/L3 kuseyinkinga. Isihloko esiphindaphindayo sengxoxo ngenxa yobunzima bezici ezahlukahlukene ezihilelekile ku-spectrum yokugcina41.
Ngaphezu kokuhlukaniswa kwe-spectral kwezimo zamakhemikhali zezifunda ezikhethiwe ezichazwe ngenhla, ukungafani kwamakhemikhali emhlabeni wonke kwezinto ezibalulekile i-Cr ne-Fe kuhlolwe ngokuhlukanisa wonke ama-spectra e-XAS atholakale ebusweni besampula kusetshenziswa indlela ye-K-means clustering. Amaphrofayili onqenqema i-Cr L abekwe ngendlela yokuthi akhe amaqoqo amabili afanele asatshalaliswe ngokwendawo kumasampula ashisiwe kanye nabandayo aqoqwe aboniswe ku-Figs. 5. Kusobala ukuthi azikho izinguquko zesakhiwo sendawo ezibonwe, njengoba ama-centroid amabili e-XAS Cr spectra afana kakhulu. Lezi zinhlobo ze-spectral zamaqoqo amabili zicishe zifane nalezo ezihambisana ne-Cr2O342, okusho ukuthi izendlalelo ze-Cr2O3 zisatshalaliswe ngokulinganayo phezu kwe-SDSS.
i-cluster yezifunda ze-K-means L-edge Cr, ama-centroid e-XAS ahambisanayo ne-b. Imiphumela yokuqhathaniswa kwe-K-means X-PEEM kwe-SDSS egoqekile ebandayo: ama-c c c ezifunda ze-K-means edge ze-Cr L2,3 kanye nama-centroid e-XAS ahambisanayo ne-d.
Ukuze kuboniswe imephu yomphetho we-FeL eyinkimbinkimbi kakhulu, amaqoqo amane nanhlanu alungiselelwe kahle kanye nama-centroid ahlobene nawo (ukusatshalaliswa kwe-spectral) asetshenziselwa amasampula asebenza ngokushisa kanye nalawo aqoqwe ngokubandayo, ngokulandelana. Ngakho-ke, iphesenti (%) le-Fe2+ kanye ne-Fe3+ lingatholakala ngokulungisa i-LCF eboniswe ku-Fig.4. I-pseudo engaba khona ye-pseudo njengomsebenzi we-Fe0 yasetshenziswa ukwembula ukungalingani kwe-microchemical kwefilimu ye-surface oxide. I-Epseudo ilinganiselwa cishe ngomthetho wokuxuba,
lapho \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) kulingana \(\rm{Fe} + 2e^ – \to\rm {Fe}^{2 + (3 + )}\), okungu-0.440 no-0.036 V, ngokulandelana. Izindawo ezine-potential ephansi zinokuqukethwe okuphezulu kwama-compound e-Fe3+. Ukusatshalaliswa okungenzeka kusampula eguquliwe ngokushisa kunohlamvu olunezingqimba olunoshintsho olukhulu olungaba ngu-0.119 V (Isithombe 6a,b). Lokhu kusatshalaliswa okungenzeka kuhlobene kakhulu ne-topography yomphezulu (Isithombe 6a). Azikho ezinye izinguquko ezihlobene nesikhundla ezibonwe ngaphakathi kwe-lamellar engaphansi (Isithombe 6b). Ngokuphambene nalokho, ngokuhlanganiswa kwama-oxide ahlukene anokuqukethwe okuhlukile kwe-Fe2+ ne-Fe3+ ku-SDSS egoqekile ebandayo, isimo esingalingani se-pseudopotential singabonakala (Isithombe 6c, d). Ama-Fe3+ oxides kanye/noma ama-oxy hydroxides yizona zinto eziyinhloko zokugqwala ensimbini futhi angena emoyeni nasemanzini50. Kulesi simo, kungabonakala ukuthi iziqhingi ezicebile ku-Fe3+ zisatshalaliswa endaweni futhi zingabhekwa njengezindawo zokugqwala. Kulesi simo, i-gradient ensimini engaba khona, kunokuba kube yinani eliphelele le-potential, ingabhekwa njengesibonakaliso sokwakheka kwezindawo zokugqwala ezisebenzayo51. Lokhu kusatshalaliswa okungafani kwe-Fe2+ kanye ne-Fe3+ ebusweni be-SDSS egoqiwe ebandayo kungashintsha izakhiwo zamakhemikhali endawo futhi kuhlinzeke indawo engaphezulu esebenza kahle ekuqhekekeni kwefilimu ye-oxide kanye nokusabela kokugqwala, ngaleyo ndlela kuvumele i-matrix yensimbi engaphansi ukuthi igqwale njalo, okuholela ekungalingani kwangaphakathi. futhi kunciphise izici zokuvikela zengqimba yokungaphazamisi.
Amaqoqo e-K-mean ezifundeni zomphetho we-Fe L2,3 kanye nama-centroid e-XAS ahambisanayo e-a-c e-hot-worked X-PEEM kanye ne-d-f cold-rolled SDSS. a, d I-K-means cluster plot embozwe esithombeni se-X-PEEM. Ama-pseudo potentials alinganiselwayo (i-epseudo) ashiwo kanye nemidwebo yeqembu le-K-means. Ukukhanya kwesithombe se-X-PEEM njengombala ku-Fig. 2 kuhambelana ngqo nokuqina kokumuncwa kwe-X-ray.
I-Cr efanayo kodwa isimo samakhemikhali esihlukile se-Fe siholela emvelaphi ehlukene yokuqhekeka kwefilimu ye-oxide kanye namaphethini okugqwala ku-Ce-2507 egoqwe ngokushisa kanye ne-cold-rolled. Le mpahla ye-Ce-2507 egoqwe ngokushisa yaziwa kahle. Ngokuphathelene nokwakheka kwama-oxide nama-hydroxide e-Fe emoyeni womoya, ukusabela okulandelayo kuvaliwe kulo msebenzi njengokusabela okungathathi hlangothi:
Ngokusekelwe ekulinganisweni kwe-X-PEEM, ukusabela okungenhla kwenzeke ezimweni ezilandelayo. Ihlombe elincane elihambisana ne-Fe0 lihlotshaniswa nensimbi yensimbi engaphansi. Ukusabela kwe-Fe yensimbi nendawo ezungezile kuholela ekwakhekeni kwengqimba ye-Fe(OH)2 (isibalo (5)), ekhulisa isignali ye-Fe2+ ku-XAS yomphetho we-L we-Fe. Ukuchayeka isikhathi eside emoyeni kuzoholela ekwakhekeni kwe-Fe3O4 kanye/noma ama-Fe2O3 oxides ngemuva kwe-Fe(OH)252,53. Izinhlobo ezimbili ze-Fe ezizinzile, i-Fe3O4 kanye ne-Fe2O3, zingakheka futhi kungqimba oluvikelayo olucebile lwe-Cr3+, lapho i-Fe3O4 ikhetha khona isakhiwo esifanayo nesihlangene. Ukuba khona kokubili kuphumela ezimweni ezixubile ze-oxidation (i-XAS-1 spectrum). I-XAS-2 spectrum ihambelana kakhulu ne-Fe3O4. Ngenkathi i-XAS-3 spectra ebonwe ezindaweni eziningana ibonise ukuguqulwa okuphelele ku-γ-Fe2O3. Njengoba ama-X-ray angasongiwe enobubanzi bokungena obungaba ngu-50 nm, isignali evela kungqimba olungaphansi iphumela ekuqineni okuphezulu kwe-A peak.
I-XRD spectrum ikhombisa ukuthi ingxenye ye-Fe efilimini ye-oxide inesakhiwo esinezingqimba, esihlanganiswe nengqimba ye-Cr oxide. Ngokungafani nesici sokungaphazamisi kokugqwala ngenxa yokungalingani kwendawo kwe-Cr2O317, naphezu kwengqimba efanayo ye-Cr2O3 kulolu cwaningo, ukumelana okuphansi kokugqwala kwabonwa kulokhu, ikakhulukazi kumasampula aqoqwe ngokubandayo. Ukuziphatha okubonwe kungaqondwa njengokungafani kwesimo se-chemical oxidation sengqimba ephezulu (Fe) ethinta ukusebenza kokugqwala. Ukudluliselwa kancane kwama-ion ensimbi noma e-oxygen ku-lattice ngenxa ye-stoichiometry efanayo yengqimba ephezulu (Fe oxide) kanye nengqimba engezansi (Cr oxide)52,53 kuholela ekusebenzisaneni okungcono (ukunamathela) phakathi kwazo. Lokhu, nakho, kuthuthukisa ukumelana nokugqwala. Ngakho-ke, i-stoichiometry eqhubekayo, okungukuthi isimo esisodwa se-oxidation se-Fe, singcono kunezinguquko ezisheshayo ze-stoichiometric. I-SDSS eguquliwe ngokushisa inobuso obufanayo kanye nengqimba yokuvikela eqine kakhulu, enikeza ukumelana okungcono kokugqwala. Kodwa-ke, nge-SDSS egoqekile ebandayo, ukuba khona kweziqhingi ezicebile nge-Fe3+ ngaphansi kwesendlalelo esivikelayo kubhubhisa ubuqotho bomphezulu futhi kubangele ukugqwala kwe-galvanic kwe-substrate eseduze, okuholela ekunciphiseni kwe-Rp (Ithebula 1) kuma-spectra e-EIS kanye nokumelana kwayo nokugqwala. Ngakho-ke, iziqhingi ezisakazeke endaweni ezicebile nge-Fe3+ ngenxa yokuguquguquka kwepulasitiki zithinta kakhulu ukusebenza kokumelana nokugqwala, okuyintuthuko kulo msebenzi. Ngakho-ke, lolu cwaningo luveza ama-spectromicrograph okunciphisa ukumelana nokugqwala ngenxa yokuguquguquka kwepulasitiki kwamasampula e-SDSS afundwe.
Ngaphezu kwalokho, yize ukuhlanganiswa komhlaba okungajwayelekile ezinsimbini zesigaba esiphindwe kabili kusebenza kangcono, ukusebenzisana kwalesi sakhi esengeziwe ne-matrix yensimbi ngayinye ngokwendlela yokuziphatha kokugqwala kusalokhu kungaqondakali ngokusekelwe ekubonweni kwe-spectroscopic microscopy. Isignali ye-Ce (eceleni kwe-XAS M-edge) ibonakala ezindaweni ezimbalwa kuphela ngesikhathi sokugoqa okubandayo, kodwa iyanyamalala ngesikhathi sokuguqulwa okushisayo kwe-SDSS, okubonisa ukufakwa kwendawo kwe-Ce ku-matrix yensimbi esikhundleni sokuhlanganiswa okufanayo. Nakuba izakhiwo ze-mechanical ze-SDSS zingathuthukiswa6,7, ukuba khona kwe-REE kunciphisa usayizi wezinto ezifakiwe futhi kucatshangwa ukuthi kuvimbela ukugoba endaweni yokuqala54.
Ekuphetheni, lo msebenzi wembula umphumela wokungafani kobuso ekugqwaleni kwe-2507 SDSS eguqulwe nge-cerium ngokulinganisa okuqukethwe kwamakhemikhali kwezingxenye ze-nanoscale. Siphendule umbuzo wokuthi kungani insimbi engagqwali igqwala ngisho noma imbozwe ngesendlalelo se-oxide esivikelayo ngokufunda ngobuningi isakhiwo esincane, isimo samakhemikhali sezici zobuso kanye nokucubungula isignali kusetshenziswa ukuhlanganiswa kwe-K-means. Kuye kwatholakala ukuthi iziqhingi ezicebile nge-Fe3+, okuhlanganisa ukuhlanganiswa kwazo kwe-octahedral kanye ne-tetrahedral kulo lonke isakhiwo se-Fe2+/Fe3+, ziwumthombo wokubhujiswa kwefilimu ye-oxide kanye nomthombo wokugqwala kwe-SDSS egoqwe ngokubandayo. Iziqhingi ze-Nanois ezilawulwa yi-Fe3+ ziholela ekumelaneni nokugqwala okubi ngisho nalapho kukhona isendlalelo esanele se-stoichiometric Cr2O3 passivating. Ngaphezu kwentuthuko yezindlela ezenziwe ekunqumeni umphumela wokungafani kwamakhemikhali e-nanoscale ekugqwaleni, umsebenzi wamanje kulindeleke ukuthi ugqugquzele izinqubo zobunjiniyela ukuthuthukisa ukumelana nokugqwala kwezinsimbi ezingagqwali ngesikhathi sokwenza insimbi.
Ukuze kulungiswe ama-ingots e-Ce-2507 SDSS asetshenziswe kulolu cwaningo, izingxenye ezixubile, okuhlanganisa i-Fe-Ce master alloy evalwe ngamapayipi ensimbi ahlanzekile, zancibilikiswa esithandweni sokungenisa esiphakathi esingama-150 kg ukuze kukhiqizwe insimbi encibilikisiwe futhi zathelwa ezikhumbeni zokubumba. Ukwakheka kwamakhemikhali okulinganisiwe (wt %) kubhalwe kuThebula Elingeziwe 2. I-ingot iqala ngokushisa ibe amabhlogo. Ngemuva kwalokho insimbi yafakwa ku-1050°C imizuzu engama-60 ibe yisisombululo esiqinile, bese icishwa emanzini kuya ekushiseni kwegumbi. Amasampula ahloliwe ahlolisiswe ngokuningiliziwe kusetshenziswa i-TEM ne-DOE ukuze kufundwe izigaba, usayizi wezinhlamvu kanye nesimo. Ulwazi oluningiliziwe mayelana namasampula kanye nenqubo yokukhiqiza lungatholakala kweminye imithombo6,7.
Cubungula amasampula ayisilinda (φ10 mm × 15 mm) ukuze kucindezelwe ngokushisa nge-axis yesilinda ehambisana nesiqondiso sokuguquguquka kwebhulokhi. Ukucindezela kokushisa okuphezulu kwenziwa ngesivinini sokucindezela esingaguquki ebangeni lika-0.01-10 s-1 emazingeni okushisa ahlukahlukene ebangeni lika-1000-1150°C kusetshenziswa i-Gleeble-3800 thermal simulator. Ngaphambi kokuguquguquka, amasampula ayeshiswa emazingeni okushisa akhethiwe ngesivinini sika-10 °C s-1 imizuzu emi-2 ukuze kuqedwe i-gradient yokushisa. Ngemva kokufinyelela ukufana kwezinga lokushisa, amasampula ashiswa abe yinani langempela lokucindezeleka elingu-0.7. Ngemva kokuguquguquka, kucinywa ngokushesha ngamanzi ukuze kugcinwe isakhiwo esikhubazekile. Ngemuva kwalokho amasampula aqinisiwe asikwa ahambisana nesiqondiso sokucindezela. Kulolu cwaningo oluthile, sikhethe isampula eshiswa ngokushisa ku-1050°C, 10 s-1 ngenxa yokuqina okuphezulu okubonwe kunezinye izibonelo7.
Amasampula amakhulu (80 × 10 × 17 mm3) esisombululo esiqinile se-Ce-2507 ahlolwe emshinini wokuguqulwa kwemigqa emibili wesigaba ezintathu ongavumelani, i-LG-300, owanikeza izakhiwo ezinhle kakhulu zemishini phakathi kwazo zonke ezinye izigaba zokuguqulwa6. Izinga lokucindezeleka kanye nokunciphisa ukujiya kwakungu-0.2 m·s-1 kanye no-5% endleleni ngayinye, ngokulandelana.
I-Autolab PGSTAT128N electrochemical workstation yasetshenziswa ukukala i-SDSS ngogesi ngemva kokugoqa okubandayo kube ngu-90% ukujiya (uhlobo lweqiniso olulinganayo oluyi-1.0) kanye nokucindezela okushisayo kube uhlobo lweqiniso oluyi-0.7 ku-1050 oC kanye ne-10 s-1. I-workstation ineseli lama-electrode amathathu eline-electrode ye-calomel egcwele njenge-electrode yokubhekisela, i-electrode ye-graphite counter, kanye nesampula ye-SDSS njenge-electrode esebenzayo. Amasampula anqunywa abe amasilinda anobubanzi obuyi-11.3 mm, ezinhlangothini lapho izintambo zethusi zazihlanganiswa khona. Isampula yabe isithelwa nge-epoxy resin, kwasala indawo evulekile yokusebenza engu-1 cm2 njenge-electrode esebenzayo (ubuso obuphansi besampula yesilinda). Qaphela ngesikhathi sokulungisa i-epoxy nangesikhathi sokusikwa nokupholisha okulandelayo ukuze ugweme ukuqhekeka. Ubuso obusebenzayo buyahlanganiswa futhi bupholishwe nge-diamond polishing suspension enobukhulu bezinhlayiya obuyi-1 micron, buhlanzwe ngamanzi acwengekile kanye ne-ethanol bese bomiswa emoyeni obandayo. Ngaphambi kokulinganisa i-electrochemical, amasampula acwebezelwe ayevezwa emoyeni izinsuku eziningana ukuze akhe ifilimu ye-oxide yemvelo. Isixazululo samanzi se-FeCl3 (6.0 wt.%), esiqiniswe nge-HCl ku-pH = 1.0 ± 0.01, sisetshenziswe ukusheshisa ukugqwala kwensimbi engagqwali55, njengoba sitholakala ezindaweni ezinolaka lapho ama-ion e-chloride ekhona khona ngamandla aqinile okuxilisa kanye ne-pH ephansi njengoba kuchaziwe yi-ASTM. Izindinganiso eziphakanyisiwe yi-G48 kanye ne-A923. Amasampula acwiliswa esixazululweni sokuhlola ihora eli-1 ngaphambi kokuba kuthathwe noma yiziphi izilinganiso ukuze kufinyelelwe esimweni esiseduze nesingaguquki. Kumasampula esisombululo esiqinile, asebenza ngokushisa kanye naqoqwayo abandayo, ububanzi bemvamisa yokulinganisa impedance babuyi-1 × 105 ~ 0.1 Hz, kanti amandla e-open-circuit (OPS) ayeyi-5 mV, okwakuyi-0.39, 0.33, kanye ne-0.25 VSCE, ngokulandelana. Ukuhlolwa ngakunye kwe-electrochemical kwanoma yisiphi isampula kwaphindwa okungenani izikhathi ezintathu ngaphansi kwezimo ezifanayo ukuqinisekisa ukuphindaphindwa kwedatha.
Ngezilinganiso ze-HE-SXRD, amabhlogo ensimbi angunxande angu-1 × 1 × 1.5 mm3 alinganiswe emgqeni we-Brockhouse wiggler onamandla aphezulu e-CLS, eCanada ukuze kulinganiswe ukwakheka kwesigaba56. Ukuqoqwa kwedatha kwenziwa ekushiseni kwegumbi ku-geometry ye-Debye-Scherrer noma i-geometry yokuthutha. Ubude be-X-rays obulinganiswe ku-calibrant ye-LaB6 bungu-0.212561 Å, obuhambisana ne-58 keV, ephakeme kakhulu kuneye-Cu Kα (8 keV) evame ukusetshenziswa njengomthombo we-X-ray welebhu. Isampula ibekwe ebangeni elingama-740 mm ukusuka kumtholi. Umthamo wokuthola wesampula ngayinye ungu-0.2 × 0.3 × 1.5 mm3, okunqunywa usayizi we-beam kanye nobukhulu besampula. Ngayinye yalezi datha iqoqwe kusetshenziswa i-Perkin Elmer area detector, i-flat panel X-ray detector, amaphikseli angu-200 µm, 40 × 40 cm2, kusetshenziswa isikhathi sokuvezwa semizuzwana engu-0.3 kanye namafreyimu angu-120.
Ukulinganiswa kwe-X-PEEM kwezinhlelo ezimbili zamamodeli ezikhethiwe kwenziwa esiteshini sokugcina se-PEEM somugqa we-Beamline MAXPEEM elabhorethri ye-MAX IV (eLund, eSweden). Amasampula alungiswa ngendlela efanayo nokulinganiswa kwe-electrochemical. Amasampula alungisiwe agcinwa emoyeni izinsuku eziningana futhi akhishwa ugesi ekamelweni le-vacuum eliphakeme kakhulu ngaphambi kokuba ashiswe ngama-photon e-synchrotron. Isixazululo samandla somsebe sitholakala ngokulinganisa i-spectrum yokuphuma kwe-ion kusuka ku-N 1 s kuya ku-1\(\pi _g^ \ast\) yesifunda sokuvuselela nge-hv = 401 eV ku-N2 kanye nokuncika kwamandla e-photon ku-E3/2.57. Ukulingana kwe-Spectral kunikeze i-ΔE (ububanzi bomugqa we-spectral) ~0.3 eV ngaphezu kobubanzi bamandla obulinganisiwe. Ngakho-ke, isixazululo samandla e-beamline silinganiselwa ukuthi siyi-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-modified SX-700 monochromator ene-Si 1200-line mm−1 grating yomphetho we-Fe 2p L2,3, umphetho we-Cr 2p L2,3, umphetho we-Ni 2p L2,3, kanye nomphetho we-Ce M4,5. Ngakho-ke, isixazululo samandla e-beamline silinganiselwa ukuthi siyi-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-modified SX-700 monochromator ene-Si 1200-line mm−1 grating yomphetho we-Fe 2p L2.3, umphetho we-Cr 2p L2.3, umphetho we-Ni 2p L2.3, kanye nomphetho we-Ce M4.5. 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, isixazululo samandla sesiteshi se-beam silinganiswe njenge-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 f/s kusetshenziswa i-monochromator ye-SX-700 eguquliwe ene-Si grating yemigqa engu-1200/mm ye-Fe edge 2p L2 ,3, i-Cr edge 2p L2.3, i-Ni edge 2p L2.3, 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-grating ye-Si engu-1200 line. 3, i-Cr edge 2p L2.3, i-Ni edge 2p L2.3 kanye ne-Ce edge M4.5.Nweba amandla e-photon ngezinyathelo ezingu-0.2 eV. Kuwo wonke amandla, izithombe ze-PEEM zaqoshwa kusetshenziswa i-TVIPS F-216 CMOS detector enoxhumano lwe-fiber optic oluyi-2 x 2 olunikeza amaphikseli angu-1024 × 1024 ensimini yokubuka engu-20 µm. Isikhathi sokuvezwa kwezithombe singamasekhondi angu-0.2, isilinganiso samafreyimu angu-16. Amandla esithombe se-photoelectron akhethwa ngendlela yokuthi anikeze isignali yesibili ephezulu kakhulu ye-electron. Zonke izilinganiso zenziwa ngokujwayelekile kwe-photon beam eqondile ephola kahle. Ukuze uthole ulwazi olwengeziwe ngezilinganiso, bheka isifundo sangaphambilini58. Ngemva kokufunda imodi yokuthola i-total electron yield (TEY)59 kanye nokusetshenziswa kwayo ku-X-PEEM, ukujula kokutholwa kwale ndlela kulinganiselwa ku-~4–5 nm yesignali ye-Cr kanye no-~6 nm yesignali ye-Fe. Ukujula kwe-Cr kuseduze kakhulu nobukhulu befilimu ye-oxide (~4 nm)60,61 kuyilapho ukujula kwe-Fe kukhulu kunobukhulu befilimu ye-oxide. I-XAS eqoqwe eduze komphetho we-Fe L iyinhlanganisela ye-iron oxide XAS kanye ne-FeO kusuka ku-matrix. Esimweni sokuqala, ukuqina kwama-electron akhishwayo kungenxa yazo zonke izinhlobo zama-electron ezingaba khona ezifaka isandla ku-TEY. Kodwa-ke, isignali yensimbi emsulwa idinga amandla aphezulu e-kinetic ukuze ama-electron adlule ungqimba lwe-oxide, afinyelele phezulu, futhi aqoqwe yi-analyzer. Kulesi simo, isignali ye-Fe0 ibangelwa kakhulu ama-electron e-LVV Auger kanye nama-electron esibili akhishwa yiwo. Ngaphezu kwalokho, ukuqina kwe-TEY okubangelwa yilawa ma-electron kuyabola ngesikhathi sokuphuma kwe-electron49 kunciphisa kakhulu isignali ye-spectral ye-Fe0 kumephu ye-iron XAS.
Ukuhlanganisa ukumbiwa kwedatha kuma-cubes edatha (idatha ye-X-PEEM) kuyisinyathelo esibalulekile ekukhipheni ulwazi olufanele (izakhiwo zamakhemikhali noma zomzimba) ngendlela enezilinganiso eziningi. Ukuhlanganiswa kwe-K-means kusetshenziswa kabanzi ezindaweni eziningana, kufaka phakathi umbono womshini, ukucutshungulwa kwesithombe, ukuqashelwa kwephethini okungagadiwe, ubuhlakani bokwenziwa, kanye nokuhlaziywa kwezigaba24. Isibonelo, ukuhlanganiswa kwe-K-means kusetshenziswa kahle ekuhlanganisweni kwedatha yesithombe se-hyperspectral62. Ngokomthetho, kudatha yezinto eziningi, i-algorithm ye-K-means ingazihlanganisa kalula ngokusho kolwazi mayelana nezimfanelo zazo (izici zamandla e-photon). Ukuhlanganiswa kwe-K-means kuyi-algorithm ephindaphindayo yokuhlukanisa idatha ibe amaqembu e-K angahlangani (amaqoqo), lapho iphikseli ngayinye ingeyeqembu elithile kuye ngokusatshalaliswa kwendawo kokungafani kwamakhemikhali ekwakhiweni kwe-microstructural yensimbi. I-algorithm ye-K-means inezinyathelo ezimbili: isinyathelo sokuqala sibala ama-centroid e-K, kanti isinyathelo sesibili sinikeza iphuzu ngalinye eqenjini elinama-centroid angomakhelwane. Isikhungo sokudonsa amandla seqembu sichazwa njengesilinganiso sezibalo samaphuzu edatha (ama-XAS spectra) alelo qembu. Kunebanga elihlukile lokuchaza ama-centroid angomakhelwane njengebanga le-Euclidean. Ukuze uthole isithombe sokufaka se-px, y (u-x no-y kuyisisombululo ngamaphikseli), i-CK iyisikhungo sokudonsa amandla seqembu; lesi sithombe singahlukaniswa (sihlanganiswe) sibe amaqoqo e-K kusetshenziswa i-K-means63. Izinyathelo zokugcina ze-algorithm yokuqoqa amaqoqo e-K yilezi:
Isinyathelo 2. Bala izinga lobulungu bawo wonke amaphikseli ngokuya nge-centroid yamanje. Isibonelo, kubalwa kusukela ebangeni lika-Euclidean d phakathi kwesikhungo nephikseli ngayinye:
Isinyathelo 3 Nika iphikseli ngayinye i-centroid eseduze. Bese ubala kabusha izikhundla ze-K centroid kanje:
Isinyathelo 4. Phinda inqubo (izilinganiso (7) kanye (8)) kuze kube yilapho ama-centroid ehlangana. Imiphumela yekhwalithi yokugcina yeqoqo ihlobene kakhulu nokukhetha okuhle kwama-centroid okuqala63. Ngesakhiwo sedatha se-PEEM sezithombe zensimbi, ngokuvamile i-X (x × y × λ) iyi-cube yedatha ye-array ye-3D, kuyilapho ama-axes e-x kanye ne-y emelela ulwazi lwesikhala (isixazululo se-pixel) kanye ne-axis ye-λ ihambisana nemodi ye-spectral yamandla yama-photon. I-algorithm ye-K-means yasetshenziswa ukuhlola izifunda ezinesithakazelo kudatha ye-X-PEEM ngokuhlukanisa ama-pixel (ama-clusters noma ama-sub-blocks) ngokwezimpawu zawo ze-spectral nokukhipha i-centroid engcono kakhulu (i-XAS spectral curve) ye-analyte ngayinye (iqoqo). Isetshenziselwa ukutadisha ukusatshalaliswa kwendawo, izinguquko ze-spectral zendawo, ukuziphatha kwe-oxidation kanye nesimo samakhemikhali. Isibonelo, i-algorithm ye-K-means clustering yasetshenziselwa izifunda ze-Fe L-edge kanye ne-Cr L-edge ku-X-PEEM esebenza kahle futhi ebandayo. Izinombolo ezahlukahlukene zama-K-clusters (izifunda ezincane) zihlolwe ukuthola ama-clusters nama-centroid amahle kakhulu. Uma igrafu iboniswa, ama-pixel aphinde abelwe kuma-centroid e-cluster afanele. Ukusatshalaliswa kombala ngakunye kuhambisana nendawo ephakathi kwe-cluster, okubonisa ukuhlelwa kwendawo kwezinto zamakhemikhali noma zomzimba. Ama-centroid akhishwe ayinhlanganisela eqondile yama-spectra amsulwa.
Imininingwane esekela imiphumela yalolu cwaningo iyatholakala kumbhali we-WC uma kucelwa ngokufanele.
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