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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 ezingeni le-microscopic, kuye ngokuthi umsuka wokungalingani kobuso unjani. Kulo msebenzi, ukungafani kwamakhemikhali ongaphezulu kwe-nanoscale okutholwe nge-spectroscopic microscopy kanye nokuhlaziywa kwe-chemometric kungalindelekile kubusa ukubola nokugqwala kwensimbi engagqwali ehlanganisiwe ebandayo i-cerium modified super duplex stainless steel 2507 (SDSS) ngesikhathi sokuziphatha kwayo kokuguquguquka okushisayo. ngakolunye uhlangothi. Nakuba i-X-ray photoelectron microscopy ibonise ukumbozwa okufanayo kwengqimba yemvelo ye-Cr2O3, i-cold rolled SDSS ibonise imiphumela emibi yokungaphazamisi ngenxa yokusatshalaliswa kwendawo kweziqhingi ezicebile ze-Fe3+ kungqimba lwe-oxide ye-Fe/Cr. Lolu lwazi ezingeni le-athomu lunikeza ukuqonda okujulile kokugqwala kwensimbi engagqwali futhi kulindeleke ukuthi kusize ekulweni nokugqwala kwezinsimbi ezifanayo ezine-alloy ephezulu.
Kusukela kwasungulwa insimbi engagqwali, ukumelana nokugqwala kwama-ferrochromium alloys kuye kwahlotshaniswa ne-chromium, eyakha i-oxide/oxyhydroxide enamandla ekhombisa ukuziphatha kokudlula ezindaweni eziningi. Uma kuqhathaniswa nezinsimbi ezingagqwali ezivamile (i-austenitic ne-ferritic), izinsimbi ezingagqwali ezi-super duplex (SDSS) ezinokumelana nokugqwala okungcono zinezakhiwo ezinhle kakhulu zemishini1,2,3. Amandla akhulayo emishini avumela imiklamo elula futhi emincane kakhulu. Ngokuphambene nalokho, i-SDSS engabizi inokumelana okuphezulu nokugqwala kwemigodi kanye ne-crevice, okuholela empilweni yenkonzo ende kanye nezicelo ezibanzi ekulawuleni ukungcola, izitsha zamakhemikhali, kanye nemboni kawoyela negesi yasogwini4. Kodwa-ke, ububanzi obuncane bamazinga okushisa okwelashwa kokushisa kanye nokwakheka okubi kuvimbela ukusetshenziswa kwayo okubanzi okusebenzayo. Ngakho-ke, i-SDSS ishintshiwe ukuze kuthuthukiswe izakhiwo ezingenhla. Isibonelo, ukuguqulwa kwe-Ce kanye nokwengezwa okuphezulu kwe-N 6, 7, 8 kwethulwa ngo-2507 SDSS (Ce-2507). Ukuhlushwa okufanele kwe-0.08 wt.% rare earth element (Ce) kunomphumela omuhle ezimpahleni zemishini ze-DSS, njengoba kuthuthukisa ukuhluzwa kokusanhlamvu kanye namandla omngcele wokusanhlamvu. Ukumelana nokuguguleka nokugqwala, amandla okuthambekela kanye namandla okukhiqiza, kanye nokusebenza kahle kokushisa nakho kuthuthukisiwe9. 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 (izinga lokushisa eliphansi, elibandayo nelishisayo) ukuze kufezwe izakhiwo ezinhle kakhulu zemishini6,7,8. Kodwa-ke, ukumelana okuhle kakhulu kokugqwala kwe-SDSS kungenxa yokuba khona kwefilimu encane ye-oxide ebusweni, ethintwa yizici eziningi, njengokuba khona kwezigaba eziningi ezinemingcele ehlukene yokusanhlamvu, ukushaqeka okungafuneki kanye nokusabela okuhlukile. isakhiwo sangaphakathi esingalingani sezigaba ezahlukahlukene ze-austenitic ne-ferritic siguqulwe 7. Ngakho-ke, ukutadisha izakhiwo ze-microdomain zamafilimu anjalo ezingeni lesakhiwo se-elekthronikhi kubaluleke kakhulu 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 nohlelo lwe-X-ray photoelectron photoelectron oluqinile luhlukanisa, kodwa ngokuvamile luyehluleka ukuhlukanisa, izimo zamakhemikhali zento efanayo ezindaweni ezahlukene esikhaleni ku-nanoscale. Izifundo eziningana zakamuva zixhumanise ukushiswa kwe-chromium yendawo nokuziphatha kokugqwala okubonwe kwezinsimbi ezingagqwali ze-austenitic ezingu-17, izinsimbi ezingagqwali ze-martensitic ezingu-18, kanye ne-SDSS 19, 20. Kodwa-ke, lezi zifundo zigxile kakhulu emthonjeni we-Cr heterogeneity (isb., isimo se-Cr3+ oxidation) ekuphikisweni kokugqwala. Ukungafani kwe-lateral ezimweni ze-oxidation zezinto kungabangelwa ama-compound ahlukene anezakhi ezifanayo, njenge-iron oxides. Lawa ma-compound adla usayizi omncane ocutshungulwe ngokushisa eduze komunye nomunye, kodwa ahlukile ngokwakheka kanye nesimo se-oxidation16,21. Ngakho-ke, ukwembula ukubhujiswa kwamafilimu e-oxide bese kuba yi-pitting kudinga ukuqonda ukungalingani kwendawo ezingeni le-microscopic. Naphezu kwalezi zidingo, ukuhlolwa kobuningi okufana nokungafani kwe-lateral oxidation, ikakhulukazi kwensimbi esikalini se-nano/atomic, kusantuleka futhi ukubaluleka kwawo kokumelana nokugqwala kusalokhu kungahlolwa. Kuze kube muva nje, isimo samakhemikhali sezinto ezahlukahlukene, njenge-Fe ne-Ca, sasichazwa ngobuningi kumasampula ensimbi kusetshenziswa i-soft X-ray photoelectron microscopy (X-PEEM) ezindaweni zokukhishwa kwemisebe ye-synchrotron ye-nanoscale. Kuhlanganiswe namasu e-X-ray absorption spectroscopy (XAS) azwela amakhemikhali, i-X-PEEM inika amandla ukulinganiswa kwe-XAS ngesisombululo esiphezulu sendawo kanye ne-spectral, ihlinzeka ngolwazi lwamakhemikhali mayelana nokwakheka kwezinto kanye nesimo samakhemikhali sawo ngesisombululo sendawo kuze kufike esikalini se-nanometer 23. Lokhu kubonwa kwe-spectroscopic kwendawo yokuqalisa ngaphansi kwe-microscope kwenza kube lula ukuhlola kwamakhemikhali endawo futhi kungabonisa ngokwendawo izinguquko zamakhemikhali ezingakaze zihlolwe ngaphambili kungqimba lwe-Fe.
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 idatha ye-K-means cluster chemometric24 ukumaka ukwakheka kwamakhemikhali omhlaba wonke (ukungafani) kwezinto ezihilelekile, kanye nezimo zawo zamakhemikhali ezivezwe ngendlela yezibalo. Ngokungafani necala lendabuko lokugqwala okubangelwa ukuwohloka kwefilimu ye-chromium oxide, ukungasebenzi kahle kwamanje kanye nokumelana nokugqwala okubi kubangelwa yiziqhingi ze-nanois ezicebile ze-Fe3+ eziseduze nongqimba lwe-oxide lwe-Fe/Cr, okungaba umphumela wama-oxide avikelayo. Endaweni yokuwohloka, kwakheka ifilimu ebangela ukugqwala.
Ukuziphatha okulimazayo kwe-SDSS 2507 okukhubazekile kwahlolwa okokuqala kusetshenziswa izilinganiso ze-electrochemical. Ku-Fig. Isithombe 1 sibonisa ama-curve e-Nyquist kanye ne-Bode amasampula akhethiwe kuzixazululo zamanzi ze-acidic (pH = 1) ze-FeCl3 ekushiseni kwegumbi. I-electrolyte ekhethiwe isebenza njenge-ejenti enamandla yokuxilisa, echaza ukuthambekela kwefilimu yokudlula ekuqhekekeni. Nakuba izinto ezisetshenzisiwe zingazange zidlule ekufakweni kokushisa kwegumbi okuzinzile, lokhu kuhlaziya kunikeze ukuqonda ngemicimbi yokwehluleka okungenzeka kanye nezinqubo zangemuva kokugqwala. Isekethe efanayo (Isithombe 1d) yasetshenziswa ukulingana ne-electrochemical impedance spectroscopy (EIS) spectra, futhi imiphumela yokufaneleka ehambisanayo iboniswe kuThebula 1. Izindilinga ezingaphelele zavela lapho kuhlolwa amasampula aphathwe ngesisombululo kanye namasampula asebenza ngokushisa, kuyilapho izindilinga ezihambisanayo ezicindezelwe zazigoqekile (Isithombe 1b). Ku-spectrum ye-EIS, i-radius ye-semicircle ingabhekwa njengokumelana kwe-polarization (Rp)25,26. I-Rp yesisombululo se-SDSS esiphathwe kuThebula 1 icishe ibe yi-135 kΩ cm-2, noma kunjalo kwi-SDSS eshisiwe nebandayo egoqiwe singabona amanani aphansi kakhulu angu-34.7 kanye no-2.1 kΩ cm–2 ngokulandelana. Lokhu kwehla okukhulu kwe-Rp kubonisa umphumela omubi wokuguqulwa kwepulasitiki ekungangeni kanye nokumelana nokugqwala, njengoba kuboniswe emibikweni yangaphambilini 27, 28, 29, 30.
I-Nyquist, b, c I-Bode impedance kanye ne-phase diagrams, kanye nemodeli yesekethe efanayo ye-d, lapho i-RS ingukumelana kwe-electrolyte, i-Rp ingukumelana kwe-polarization, kanti i-QCPE iyi-constant phase element oxide esetshenziselwa ukulingisa i-non-ideal capacitance (n) . Ukulinganiswa kwe-EIS kwenziwa nge-no-load potential.
Ama-constant okuqala aboniswa ku-Bode diagram kanti i-high frequency plateau imelela ukumelana kwe-electrolyte RS26. Njengoba imvamisa incipha, i-impedance iyanda futhi kutholakala i-negative phase angle, okubonisa ukubusa kwe-capacitance. I-phase angle iyanda, igcina inani layo eliphezulu ebangeni lemvamisa elibanzi, bese incipha (Umfanekiso 1c). Kodwa-ke, kuzo zonke izimo ezintathu leli nani eliphakeme lisangaphansi 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 okususelwa ekuqineni kobuso noma ekungalingani, ikakhulukazi ngokwesilinganiso se-athomu, i-fractal geometry, i-electrode porosity, i-non-uniform potential, kanye nokusatshalaliswa kwamanje okuxhomeke ebusweni. I-Electrode geometry31,32. I-CPE impedance:
lapho u-j eyinombolo ecatshangelwayo kanti u-ω uyimvamisa ye-angular. I-QCPE iyi-frequency engaguquki ehambisana nendawo evulekile esebenzayo ye-electrolyte. i-n iyinombolo yamandla engenakulinganiswa echaza ukuphambuka ekuziphatheni okuhle kwe-capacitor, okungukuthi u-n oseduze no-1, i-CPE eseduze ne-capacitance emsulwa, futhi uma u-n eseduze no-zero, kuwukumelana. Ukuphambuka okuncane kuka-n, eduze no-1, kubonisa ukuziphatha okuhle kwe-capacitor ebusweni ngemva kokuhlolwa kwe-polarization. I-QCPE ye-cold rolled SDSS iphakeme kakhulu kunemikhiqizo efanayo, okusho ukuthi ikhwalithi yobuso ayifani kangako.
Ngokuhambisana nezakhiwo eziningi zokumelana nokugqwala kwezinsimbi ezingagqwali, okuqukethwe okuphezulu kwe-Cr kwe-SDSS ngokuvamile kuphumela ekumelaneni nokugqwala okuphezulu kwe-SDSS ngenxa yokuba khona kwefilimu ye-oxide evikelayo engasebenzisi i-passive ebusweni17. Le filimu edlulisa i-passive ngokuvamile inothile ngama-oxide e-Cr3+ kanye/noma ama-hydroxide, ikakhulukazi ahlanganisa ama-oxide e-Fe2+, ama-Fe3+ kanye/noma ama-hydroxide (oxy) 33. Naphezu kokufana okufanayo kobuso, ungqimba lwe-oxide edlulisa i-passive, kanye nokuqhekeka okubonakalayo ebusweni, njengoba kunqunywa yizithombe ezincane,6,7 ukuziphatha kokugqwala kwe-SDSS esebenza ngokushisa kanye ne-cold-rolled kuhlukile futhi ngakho-ke kudinga ucwaningo olujulile lwesakhiwo se-deformation kanye nesici sesakhiwo sensimbi.
Isakhiwo esincane sensimbi engagqwali esiguquliwe sihlolwe ngobuningi kusetshenziswa ama-X-ray angaphakathi nawamandla aphezulu e-synchrotron (Izithombe Ezingeziwe 1, 2). Ukuhlaziywa okuningiliziwe kunikezwe kulwazi olungeziwe. Nakuba lokhu kuhambisana kakhulu nohlobo lwesigaba esiyinhloko, umehluko utholakale ezingxenyeni zevolumu zezigaba, ezibalwe kuThebula Elingeziwe 1. Umehluko ungase ubangelwe yingxenye yesigaba esingafani ebusweni kanye nengxenye yevolumu (XRD) encike ekujuleni okuhlukile kokutholwa ngokusebenzisa i-X-ray diffraction enemithombo ehlukahlukene yamandla yama-photon esigameko. Ingxenye ephezulu kakhulu ye-austenite kumasampula aqoqwe ngokubandayo, enqunywe yi-XRD emthonjeni webhubhoratri, ikhombisa ukudlula okungcono kanye nokumelana nokugqwala okungcono kamuva35, kuyilapho imiphumela enembile kakhulu neyezibalo ikhombisa izitayela eziphambene ngezilinganiso zesigaba. Ngaphezu kwalokho, ukumelana nokugqwala kwensimbi nakho kuncike ezingeni lokucwengwa kokusanhlamvu, ukunciphisa usayizi wokusanhlamvu, ukwanda kokuguquguquka okuncane kanye nobuningi bokuhlukaniswa okwenzeka ngesikhathi sokwelashwa kwe-thermomechanical36,37,38. Amasampula asebenza ngokushisa abonisa uhlobo olunezinhlayiya eziningi, olubonisa okusanhlayiya okusanhlayiya okusanhlayiya okusanhlayiya, kuyilapho amasongo abushelelezi abonwe kumasampula aqoqwe ngokubandayo (Isithombe Esingeziwe 3) abonisa ukucwengwa okukhulu kokusanhlayiya ku-nanoscale emsebenzini wangaphambilini6, okufanele kufake isandla ekungangeni kwefilimu. Ubuningi obukhulu bokuhlukaniswa kwezicubu buvame ukuhlotshaniswa nokumelana okuphansi kokufakwa kwezicubu, okuhambisana kahle nokulinganiswa kwe-electrochemical.
Izinguquko ezimweni zamakhemikhali zama-microdomains ezinto eziyisisekelo ziye zafundwa ngokuhlelekile kusetshenziswa i-X-PEEM. Naphezu kobuningi bezinto ezixubile, i-Cr, i-Fe, i-Ni, ne-Ce39 zikhethwe lapha ngoba i-Cr iyisici esiyinhloko sokwakheka kwefilimu yokudlulisa, i-Fe iyisici esiyinhloko ensimbini, kanti i-Ni ithuthukisa ukudlulisa futhi ilinganisela isakhiwo sesigaba se-ferrite-austenitic kanye nenhloso yokuguqula i-Ce. Ngokulungisa amandla emisebe ye-synchrotron, i-RAS yambozwa kusukela ebusweni ngezici eziyinhloko ze-Cr (edge ​​​​L2.3), i-Fe (edge ​​​​L2.3), i-Ni (edge ​​​​L2.3) kanye ne-Ce (edge ​​​​M4.5). ukwakheka okushisayo kanye nokugoqa okubandayo kwe-Ce-2507 SDSS. Ukuhlaziywa kwedatha okufanele kwenziwe ngokufaka ukulinganiswa kwamandla nedatha eshicilelwe (isb. i-XAS 40, 41 ku-Fe L2, imiphetho emi-3).
Ku-Fig. Isithombe 2 sibonisa izithombe ze-X-PEEM ze-hot-worked (Isithombe 2a) kanye ne-cold-rolled (Isithombe 2d) Ce-2507 SDSS kanye nemiphetho ye-XAS ehambisanayo ye-Cr kanye ne-Fe L2,3 ezindaweni ezimakwe ngazinye. Umphetho we-L2,3 we-XAS uhlola izimo ze-3d ezingenamuntu ngemuva kokukhishwa kwe-electron emazingeni okuhlukanisa i-spin-orbit 2p3/2 (umphetho we-L3) kanye ne-2p1/2 (umphetho we-L2). Ulwazi mayelana nesimo se-valence se-Cr lutholakale ku-XAS emphethoni we-L2,3 ku-Fig. 2b, e. Ukuqhathaniswa namajaji. 42,43 kubonise ukuthi iziqongo ezine zibonwe eduze komphetho we-L3, ezibizwa ngokuthi i-A (578.3 eV), i-B (579.5 eV), i-C (580.4 eV) kanye ne-D (582.2 eV), ezibonisa i-octahedral Cr3+, ehambisana ne-Cr2O3 ion. Ama-spectra okuhlola ayavumelana nezibalo zethiyori eziboniswe kumaphaneli b no-e, ezitholwe ekubalweni okuningi kwensimu yekristalu esixhumi 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 sokushisa se-X-PEEM se-SDSS esiguquliwe ngokushisa esihambisana nomngcele we-b Cr L2.3 kanye nomngcele we-c Fe L2.3, d isithombe sokushisa se-X-PEEM se-SDSS egoqiwe ebandayo esihambisana nomngcele we-e Cr L2.3 kanye nohlangothi lomngcele we-f Fe L2 .3 (f). Ama-spectra e-XAS adwetshwe ezindaweni ezahlukene zesikhala ezimakwe ezithombeni zokushisa (a, d), imigqa ephuzi enamachashazi ku-(b) kanye no-(e) imelela ama-spectra e-XAS alingisiwe e-Cr3+ anenani lensimu yekristalu elingu-2.0 eV. Ezithombeni ze-X-PEEM, sebenzisa i-palette yokushisa ukuze uthuthukise 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 asizange sishintshe. Umdwebo owengeziwe. Izibalo 5-9 zibonisa izithombe ze-X-PEEM kanye nama-spectra e-XAS ahambisanayo e-Ni ne-Ce ezindaweni ezahlukahlukene ebusweni bezibonelo ezishisiwe neziqoqiwe. I-Ni XAS ikhombisa izimo ze-oxidation ze-Ni2+ phezu kobuso bonke obulinganisiwe bezibonelo ezishisiwe neziqoqiwe (Ingxoxo Engeziwe). Kufanele kuqashelwe ukuthi, esimweni samasampula ashisiwe, isignali ye-XAS ye-Ce ayizange ibonwe, kanti esimweni samasampula aqoqiwe abandayo, kwabonakala i-spectrum ye-Ce3+. Ukubonwa kwamabala e-Ce kumasampula aqoqiwe abandayo kubonise ukuthi i-Ce ivela kakhulu ngesimo se-precipitates.
Ku-SDSS eguquliwe ngokwesimo sokushisa, akukho shintsho lwesakhiwo sendawo ku-XAS emphethweni we-Fe L2,3 olubonwe (Umfanekiso 2c). Kodwa-ke, i-Fe matrix micro-regionally ishintsha isimo sayo samakhemikhali ezindaweni eziyisikhombisa ezikhethwe ngokungahleliwe ze-SDSS ebandayo, njengoba kuboniswe ku-Fig. 2f. Ngaphezu kwalokho, ukuze kutholakale umbono onembile wezinguquko esimweni se-Fe ezindaweni ezikhethiwe ku-Fig. 2f, kwenziwa izifundo zobuso bendawo (Umfanekiso 3 kanye nomfanekiso owengeziwe 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 ngokubalwa kwensimu yekristalu eminingi 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 ezahlukene45,46, i-Fe3O4 inenhlanganisela ye-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 ukumelwa yi-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 ephepheni elidlule,45 yize isilinganiso sokuqina salokhu okubili sihlukile, isilinganiso sawo sokuqina isib/t2g singu-≈1, kanti kulokhu isilinganiso sokuqina esibonwe isib/t2g sicishe sibe ngu-1. Lokhu kuqeda amathuba okuthi esimweni samanje yi-Fe3+ kuphela ekhona. Uma sibheka isimo se-Fe3O4 kokubili i-Fe2+ ne-Fe3+, isici sokuqala, esaziwa ngokuba nomphetho we-L3 obuthakathaka (oqinile) we-Fe, sibonisa inani elincane (elikhudlwana) lezimo ze-t2g ezingenamuntu. Lokhu kusebenza ku-Fe2+ (Fe3+), okubonisa ukuthi isici sokuqala sokwanda sibonisa ukwanda kokuqukethwe kwe-Fe2+47. Le miphumela ikhombisa ukuthi ukuba khona kwe-Fe2+ kanye ne-γ-Fe2O3, i-α-Fe2O3 kanye/noma i-Fe3O4 kubusa ebusweni obugoqekile obubandayo bezinto ezihlanganisiwe.
Izithombe ezikhulisiwe zesithombe sokushisa se-photoelectron se-XAS spectra (a, c) kanye no-(b, d) zidlula umphetho we-Fe L2,3 ezindaweni ezahlukahlukene zesikhala ngaphakathi kwezifunda ezikhethiwe 2 kanye no-E ku-Figs. 2d.
Idatha yokuhlola etholakele (Isithombe 4a kanye nesithombe esengeziwe 11) idwetshwe futhi iqhathaniswa nedatha yamakhemikhali ahlanzekile 40, 41, 48. Izinhlobo ezintathu ezahlukene ze-Fe L-edge XAS spectra ebonwe ngokuhlola (XAS-1, XAS-2 kanye ne-XAS-3: Isithombe 4a). Ikakhulukazi, i-spectrum 2-a (ekhonjiswe njenge-XAS-1) ku-Fig. 3b elandelwa yi-spectrum 2-b (ebhalwe nge-XAS-2) ibonwe kuyo yonke indawo yokuthola, kuyilapho ama-spectra afana ne-E-3 abonwe ku-figure 3d (ebhalwe nge-XAS-3) abonwe ezindaweni ezithile. Njengomthetho, kusetshenziswe amapharamitha amane ukuhlonza izimo ze-valence ezikhona kusampula engaphansi kocwaningo: (1) izici ze-spectral L3 kanye ne-L2, (2) izikhundla zamandla zezici L3 kanye ne-L2, (3) umehluko wamandla 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 obusafundwa. Isilinganiso sokuqina esibaliwe i-L2/L3 siphinde sabonisa ukuba khona kwazo zonke izingxenye ezintathu.
i-XAS spectra elingisiwe ye-Fe enedatha yokuhlola emithathu ehlukene ebonwe (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-3) Ukuqhathanisa, i-Octahedrons Fe2+, i-Fe3+ enamanani ensimu yekristalu angu-1.0 eV kanye ne-1.5 eV, ngokulandelana, idatha yokuhlola elinganiswe nge-bd (XAS-1, XAS-2, XAS-3) kanye nedatha ye-LCF elungiselelwe ehambisanayo (umugqa omnyama oqinile), kanye nasesimweni se-XAS-3 spectra ene-Fe3O4 (isimo esixubile se-Fe) kanye nezindinganiso ze-Fe2O3 (i-Fe3+ emsulwa).
Ukulingana okuhlanganisiwe okuqondile (LCF) kwezindinganiso ezintathu 40, 41, 48 kwasetshenziswa ukulinganisa 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 yokuthi sibone i-ledge encane kuyo yonke idatha, kanye nangenxa yokuthi 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.事实上，X-PEEM 对Fe（~6 nm）49的检测深度大于估计的氧化层厚度（略> 4 nm），允许检测來自钝化层下方的铁基体（Fe0）的信号。事实上 , X-PEEM 对 Fe （~ 6 nm） 49 的 检测 深度 大于 的 氧化层 厚度 略 略> 4 nm） 允测下方 铁基体 (fe0) 的。 信号 信号 信号 信号 信号 信号Фактически, глубина обнаружения Fe (~ 6 нм) 49 с помощью X-PEEM больше, чем предполагаемая толщина оксидного слоя (немного > 4 обнаруживать сигнал от железной матрицы (Fe0) ниже пассивирующего слоя. Eqinisweni, ukujula kokutholwa kwe-Fe (~6 nm) 49 yi-X-PEEM kukhulu kunobukhulu obulindelekile bengqimba ye-oxide (kancane > 4 nm), okuvumela ukutholwa kwesignali evela ku-iron matrix (Fe0) ngaphansi kwengqimba ye-passivation. .Kwenziwa inhlanganisela ehlukahlukene ye-Fe2+ ne-Fe3+ ukuze kutholakale ikhambi elingcono kakhulu ledatha yokuhlola ebonwe. Ku-fig. 4b kukhombisa i-XAS-1 spectrum yokuhlanganiswa kwe-Fe2+ ne-Fe3+, lapho izilinganiso ze-Fe2+ ne-Fe3+ zazifana cishe ngo-45%, okubonisa izimo ze-oxidation ezixubile ze-Fe. Ngenkathi ku-XAS-2 spectrum, iphesenti le-Fe2+ ne-Fe3+ liba ngu-~30% no-60%, ngokulandelana. I-Fe2+ ​​ingaphansi kwe-Fe3+. Isilinganiso se-Fe2+ ne-Fe3, esilingana no-1:2, sisho ukuthi i-Fe3O4 ingakhiwa ngesilinganiso esifanayo phakathi kwama-ion e-Fe. Ngaphezu kwalokho, ku-XAS-3 spectrum, iphesenti le-Fe2+ ne-Fe3+ liba ngu-~10% no-80%, okubonisa ukuguqulwa okuphezulu kwe-Fe2+ ku-Fe3+. Njengoba kushiwo ngenhla, i-Fe3+ ingavela ku-α-Fe2O3, γ-Fe2O3 noma i-Fe3O4. Ukuze kuqondwe umthombo ongaba khona we-Fe3+, i-XAS-3 spectrum yadwetshwa ngezindinganiso ezahlukene ze-Fe3+ ku-Figure 4e, okubonisa ukufana kuzo zombili izindinganiso lapho kucatshangelwa i-B peak. Kodwa-ke, ukuqina kweziqongo zamahlombe (A: kusuka ku-Fe2+) kanye nesilinganiso sokuqina kwe-B/A kubonisa ukuthi i-spectrum ye-XAS-3 iseduze, kodwa ayihambisani ne-spectrum ye-γ-Fe2O3. Uma kuqhathaniswa ne-bulk γ-Fe2O3, i-Fe 2p XAS peak ye-A SDSS inamandla aphezulu kancane (Isithombe 4e), okubonisa ukuqina okuphezulu kwe-Fe2+. Nakuba i-spectrum ye-XAS-3 ifana ne-γ-Fe2O3, lapho i-Fe3+ ikhona khona ezikhundleni ze-Oh ne-Td, ukuhlonza izimo ezahlukene ze-valence kanye nokuxhumana kuphela eceleni komphetho we-L2,3 noma i-L2/L3 intensity ratio kusalokhu kuyinkinga. isihloko sengxoxo eqhubekayo ngenxa yobunzima bezici ezahlukene ezithinta i-spectrum yokugcina41.
Ngaphezu komehluko we-spectral esimweni samakhemikhali sezindawo ezikhethiwe ezichazwe ngenhla, ukungafani kwamakhemikhali emhlabeni wonke kwezinto ezibalulekile i-Cr ne-Fe nakho kwahlolwa ngokuhlukanisa wonke ama-spectra e-XAS atholakale ebusweni besampula kusetshenziswa indlela ye-K-means clustering. . Amaphrofayili e-Edge Cr L asethelwe ukwakha amaqoqo amabili afanele asatshalaliswa ngokwendawo kumasampula ashisiwe kanye nabandayo aqoqwe aboniswe ku-Figs. 5. Kusobala ukuthi azikho izinguquko zesakhiwo sendawo ezibhekwa njengezifanayo, njengoba ama-centroid amabili e-XAS Cr spectra afanayo. Lezi zinhlobo ze-spectral zamaqoqo amabili zicishe zifane nalezo ezihambisana ne-Cr2O342, okusho ukuthi izendlalelo ze-Cr2O3 zihlukaniswe ngokulinganayo ku-SDSS.
I-Cr L K-means edge region clusters, kanti i-b iyi-XAS centroids ehambisanayo. Imiphumela yokuqhathaniswa kwe-K-means X-PEEM kwe-SDSS egoqekile ebandayo: c I-Cr L2.3 edge region yama-K-means clusters kanye ne-d ehambisanayo ye-XAS centroids.
Ukuze kuboniswe amamephu onqenqema lwe-FeL ayinkimbinkimbi kakhulu, amaqoqo amane nanhlanu alungiselelwe kahle kanye nama-centroid ahlobene nawo (amaphrofayili e-spectral) asetshenziswe kumasampula asebenza ngokushisa kanye nalawo aqoqwe ngokubandayo, ngokulandelana. Ngakho-ke, iphesenti (%) le-Fe2+ kanye ne-Fe3+ lingatholakala ngokufaka 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 \(\rm{Fe} + 2e^ – \ kuya ku \rm {Fe}^{2 + (3 + )}\), 0.440 kanye no-0.036 V, ngokulandelana. Izifunda ezine-potential ephansi zinokuqukethwe okuphezulu kwe-Fe3+ compound. Ukusatshalaliswa okungenzeka kumasampula aguquliwe 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 ezincike endaweni ngaphakathi kwe-laminar engaphansi ezibonwe (Isithombe 6b). Ngokuphambene nalokho, ngokuxhumeka kwama-oxide ahlukene anokuqukethwe okuhlukile kwe-Fe2+ ne-Fe3+ ku-SDSS egoqekile ebandayo, umuntu angabona uhlobo olungalingani lwe-pseudopotential (Isithombe 6c, d). Ama-Fe3+ oxides kanye/noma ama-oxy hydroxide yizona zinto eziyinhloko zokugqwala ensimbini futhi angena emoyeni nasemanzini50. Kulesi simo, iziqhingi ezicebile ku-Fe3+ zibhekwa njengezisakazeke endaweni futhi zingabhekwa njengezindawo ezigqwalile. Ngesikhathi esifanayo, i-gradient ensimini engaba khona, kunokuba kube yinani eliphelele le-potential, ingasetshenziswa njengesibonakaliso sokwakheka kwezindawo zokugqwala ezisebenzayo. Lokhu kusatshalaliswa okungalingani kwe-Fe2+ kanye ne-Fe3+ ebusweni be-SDSS egoqiwe ebandayo kungashintsha i-chemistry yendawo futhi kuhlinzeke indawo engaphezulu esebenzayo ekwaphukeni kwefilimu ye-oxide kanye nokusabela kokugqwala, ngaleyo ndlela kuvumele ukugqwala okuqhubekayo kwe-matrix yensimbi engaphansi, okuholela ekugqwaleni kwangaphakathi. ukungafani kwezakhiwo kanye nokwehla kwezakhiwo zokuvikela zengqimba yokungaphazamisi.
Amaqoqo e-K-means kanye nama-centroid e-XAS ahambisanayo esifundeni somphetho we-Fe L2.3 we-hot-deformed X-PEEM ac kanye ne-df ye-cold-rolled SDSS. a, d Ama-K-means cluster plots ambozwe ezithombeni ze-X-PEEM. I-pseudo potential ebaliwe (i-Epseudo) ishiwo kanye ne-K-means cluster plot. Ukukhanya kwesithombe se-X-PEEM, njengombala ku-Fig. 2 kuhambelana nokuqina kokumuncwa kwe-X-ray.
I-Cr efanayo kodwa isimo samakhemikhali esihlukile se-Fe siholela ekulimaleni kwefilimu ye-oxide ehlukene kanye namaphethini okugqwala ku-Ce-2507 esebenza ngokushisa kanye ne-cold-rolled. Le mpahla ye-Ce-2507 egingqiwe ebandayo ifundwe kahle. Ngokuphathelene nokwakheka kwama-oxide nama-hydroxide e-Fe emoyeni ozungezile kulo msebenzi ocishe ungathathi hlangothi, ukusabela kungokulandelayo:
Ukusabela okungenhla kwenzeka kulezi zimo ezilandelayo ngokusekelwe ekuhlaziyweni kwe-X-PEEM. Ihlombe elincane elihambisana ne-Fe0 lihlotshaniswa nensimbi yensimbi engaphansi. Ukusabela kwe-metallic Fe nemvelo kuphumela ekwakhekeni kwengqimba ye-Fe(OH)2 (isibalo (5)), ethuthukisa isignali ye-Fe2+ ku-Fe L-edge XAS. Ukuchayeka isikhathi eside emoyeni kungabangela ukwakheka kwe-Fe3O4 kanye/noma ama-Fe2O3 oxides ngemva kwe-Fe(OH)252,53. Izinhlobo ezimbili ezizinzile ze-Fe, i-Fe3O4 kanye ne-Fe2O3, zingakheka futhi kungqimba oluvikelayo olucebile lwe-Cr3+, lapho i-Fe3O4 ikhetha khona isakhiwo esifanayo nesinamathelayo. Ukuba khona kokubili kuphumela ezimweni ezixubile ze-oxidation (i-XAS-1 spectrum). I-XAS-2 spectrum ihambelana kakhulu ne-Fe3O4. Ngenkathi ukubonwa kwe-XAS-3 spectra ezindaweni eziningana kubonise ukuguqulwa okuphelele ku-γ-Fe2O3. Njengoba ukujula kokungena kwe-X-rays evulekile kungama-50 nm, isignali evela kungqimba olungezansi iholela ekuqineni okuphezulu kwe-A peak.
I-XPA spectrum ikhombisa ukuthi ingxenye ye-Fe efilimini ye-oxide inesakhiwo esinezingqimba esihlanganiswe nengqimba ye-Cr oxide. Ngokungafani nezimpawu zokungaguquguquki ngenxa yokungalingani kwendawo kwe-Cr2O3 ngesikhathi sokugqwala, naphezu kwengqimba efanayo ye-Cr2O3 kulo msebenzi, ukumelana okuphansi kokugqwala kuyabonwa kulokhu, ikakhulukazi kumasampula aqoqwe ngokubandayo. Ukuziphatha okubonwe kungaqondwa njengokungafani kwesimo se-chemical oxidation engqimbeni ephezulu (Fe), okuthinta ukusebenza kokugqwala. Ngenxa ye-stoichiometry efanayo yengqimba ephezulu (i-iron oxide) kanye nengqimba engezansi (i-chromium oxide)52,53 ukusebenzisana okungcono (ukunamathela) phakathi kwazo kuholela ekuthuthweni okuhamba kancane kwama-ion ensimbi noma e-oxygen e-lattice, okuholela ekwandeni kokumelana nokugqwala. Ngakho-ke, isilinganiso esiqhubekayo se-stoichiometric, okungukuthi isimo esisodwa se-oxidation se-Fe, singcono kunezinguquko ezisheshayo ze-stoichiometric. I-SDSS eguquliwe ukushisa inobuso obufanayo, ungqimba oluvikelayo oluqinile, kanye nokumelana nokugqwala okungcono. Ngenkathi kwi-SDSS egoqekile ebandayo, ukuba khona kweziqhingi ezicebile nge-Fe3+ ngaphansi kwesendlalelo esivikelayo kwephula ubuqotho bomphezulu futhi kubangele ukugqwala kwe-galvanic nge-substrate eseduze, okuholela ekwehleni okukhulu kwe-Rp (Ithebula 1). I-EIS spectrum kanye nokumelana kwayo nokugqwala kuncishisiwe. Kungabonakala ukuthi ukusatshalaliswa kwendawo kweziqhingi ezicebile nge-Fe3+ ngenxa yokuguqulwa kwepulasitiki kuthinta kakhulu ukumelana nokugqwala, okuyintuthuko kulo msebenzi. Ngakho-ke, lolu cwaningo luveza izithombe ezincane kakhulu ze-spectroscopic zokunciphisa ukumelana nokugqwala kwamasampula e-SDSS afundwe ngendlela yokuguqulwa kwepulasitiki.
Ngaphezu kwalokho, nakuba ukuhlanganiswa nezinto zomhlaba ezingavamile ezinsimbini ezinezigaba ezimbili kubonisa ukusebenza okungcono, ukusebenzisana kwalesi sakhi sokwengeza ne-matrix yensimbi ngayinye ngokwendlela yokuziphatha kokugqwala ngokusho kwedatha ye-spectroscopic microscopy kusalokhu kungaqondakali. Ukuvela kwezimpawu ze-Ce (nge-XAS M-edges) kubonakala ezindaweni ezimbalwa kuphela ngesikhathi sokugoqa okubandayo, kodwa kuyanyamalala ngesikhathi sokuguqulwa okushisayo kwe-SDSS, okubonisa imvula yendawo ye-Ce ku-matrix yensimbi, kunokuba kuhlanganiswe ngokulinganayo. Nakuba kungathuthukisi kakhulu izakhiwo ze-SDSS6,7, ukuba khona kwezinto zomhlaba ezingavamile kunciphisa usayizi wezinto ezifakiwe futhi kucatshangwa ukuthi kuvimbela ukugoba esifundeni sokuqala54.
Ekuphetheni, lo msebenzi wembula umphumela wokungafani kobuso ekugqwaleni kwe-2507 SDSS eguqulwe nge-cerium ngokulinganisa okuqukethwe kwamakhemikhali kwezingxenye ze-nanoscale. Siphendula umbuzo wokuthi kungani insimbi engagqwali igqwala ngisho nangaphansi kwesendlalelo se-oxide esivikelayo ngokulinganisa isakhiwo sayo esincane, i-surface chemistry, kanye nokucubungula isignali kusetshenziswa i-K-means clustering. Kuye kwatholakala ukuthi iziqhingi ezicebile nge-Fe3+, okuhlanganisa ukuhlanganiswa kwazo kwe-octahedral kanye ne-tetrahedral kuyo yonke isici se-Fe2+/Fe3+ exubile, ziwumthombo womonakalo kanye nokugqwala kwefilimu ye-oxide egoqwe ngokubandayo i-SDSS. Iziqhingi ze-Nanois ezilawulwa yi-Fe3+ ziholela ekumelaneni nokugqwala okubi ngisho nalapho kukhona isendlalelo esanele se-stoichiometric Cr2O3 passivating. Ngaphezu kwentuthuko yezindlela ekunqumeni umphumela wokungafani kwamakhemikhali e-nanoscale ekugqwaleni, umsebenzi oqhubekayo kulindeleke ukuthi ugqugquzele izinqubo zobunjiniyela ukuthuthukisa ukumelana nokugqwala kwezinsimbi ezingagqwali ngesikhathi sokwenza insimbi.
Ukuze kulungiswe ingot ye-Ce-2507 SDSS esetshenziswe kulolu cwaningo, ukwakheka okuxubile okuhlanganisa i-Fe-Ce master alloy evalwe ngethubhu yensimbi emsulwa kwancibilikiswa esithandweni sokungenisa esiphakathi esingamakhilogremu angu-150 ukuze kukhiqizwe insimbi encibilikisiwe futhi kwathelwa esikhumbeni. Ukwakheka kwamakhemikhali okulinganisiwe (wt%) kubhalwe kuThebula Elingeziwe 2. Ama-ingot aqala ngokushisa ahlanganiswe abe amabhlogo. Ngemuva kwalokho afakwa ku-1050°C imizuzu engama-60 ukuze kutholakale insimbi esimweni sesisombululo esiqinile, bese ecinywa 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.
Amasampula e-cylindrical (φ10 mm×15 mm) okucindezela okushisayo acutshungulwa ukuze i-axis yesilinda ihambisane nesiqondiso sokuguquguquka kwebhloko. Ukucindezela kokushisa okuphezulu kwenziwa emazingeni okushisa ahlukahlukene ebangeni lika-1000-1150°C kusetshenziswa i-Gleeble-3800 thermal simulator ngesivinini sokucindezela esingaguquki ebangeni lika-0.01-10 s-1. Ngaphambi kokuguquguquka, amasampula ashiswa ngesivinini sika-10 °C s-1 imizuzu emi-2 ekushiseni okukhethiwe ukuze kuqedwe i-gradient yokushisa. Ngemva kokufinyelela ukufana kwezinga lokushisa, isampula yashiswa yaba yinani langempela lokucindezela elingu-0.7. Ngemva kokuguquguquka, amasampula acinywa ngokushesha ngamanzi ukuze kulondolozwe isakhiwo esikhubazekile. Isampula eqinile ibe isinqunywa ngokuhambisana nesiqondiso sokucindezela. Kulolu cwaningo oluthile, sikhethe isampula enesimo sokucindezela okushisayo esingu-1050°C, 10 s-1 ngoba ubulukhuni obubonakalayo babuphezulu kunezinye izibonelo7.
Amasampula amakhulu (80 × 10 × 17 mm3) esisombululo esiqinile se-Ce-2507 asetshenziswe kumshini wokugaya we-LG-300 onezigaba ezintathu ongavumelanisi onezici ezinhle kakhulu zemishini phakathi kwawo wonke amanye amazinga okuguquguquka6. Izinga lokucindezeleka kanye nokunciphisa ukujiya kwendlela ngayinye kungu-0.2 m·s-1 kanye no-5%, ngokulandelana.
I-Autolab PGSTAT128N electrochemical workstation yasetshenziswa ekulinganisweni kwe-SDSS electrochemical ngemva kokugoqa okubandayo kuze kube ukwehla okungu-90% kobukhulu (uhlobo lweqiniso olulinganayo oluyi-1.0) kanye nangemva kokucindezela okushisayo ku-1050°C imizuzu eyi-10 kuya kuhlobo lweqiniso oluyi-0.7. 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. Amasampula abe eseqiniswa nge-epoxy, kwasala indawo evulekile yokusebenza engu-1 cm2 njenge-electrode esebenzayo (uhlangothi olungezansi lwesampula ye-cylindrical). Qaphela ngesikhathi sokulungisa i-epoxy kanye nokusikwa nokupholisha okulandelayo ukuze ugweme ukuqhekeka. Izindawo zokusebenza zagaywa futhi zapholisha nge-diamond polishing suspension enobukhulu bezinhlayiya obuyi-1 μm, zagezwa ngamanzi acwengekile kanye ne-ethanol, futhi zomiswa emoyeni obandayo. Ngaphambi kokulinganiswa kwe-electrochemical, amasampula acwengekile ayevezwa emoyeni izinsuku eziningana ukuze akhe ifilimu ye-oxide yemvelo. Isixazululo samanzi se-FeCl3 (6.0 wt%), esizinzile ku-pH = 1.0 ± 0.01 nge-HCl ngokwezincomo ze-ASTM, sisetshenziselwa ukusheshisa ukugqwala kwensimbi engagqwali55 ngoba iyagqwala lapho kukhona ama-ion e-chloride anamandla amakhulu okuxilisa kanye ne-pH ephansi Izindinganiso zemvelo i-G48 kanye ne-A923. Faka isampula esixazululweni sokuhlola ihora eli-1 ukuze ufinyelele esimweni esizinzile ngaphambi kokwenza noma yiziphi izilinganiso. Kumasampula esisombululo esiqinile, esakhiwe ngokushisa, kanye nasokugoqwa okubandayo, izilinganiso ze-impedance zenziwa kuma-potentials e-open circuit (OPC) angu-0.39, 0.33, kanye no-0.25 V, ngokulandelana, ebangeni lemvamisa kusukela ku-1 105 kuya ku-0.1 Hz nge-amplitude engu-5 mV. Zonke izivivinyo zamakhemikhali ziphindwe okungenani izikhathi ezi-3 ngaphansi kwezimo ezifanayo ukuqinisekisa ukuphindaphindwa kwedatha.
Ngezilinganiso ze-HE-SXRD, amabhlogo ensimbi angunxande angunxande alinganisa u-1 × 1 × 1.5 mm3 alinganiswa ukuze kulinganiswe ukwakheka kwesigaba se-beam se-Brockhouse high-energy wiggler e-CLS, eCanada56. Ukuqoqwa kwedatha kwenziwa ku-Debye-Scherrer geometry noma i-geometry yokudlulisela ekushiseni kwegumbi. Ubude be-X-ray obulinganiswe nge-LaB6 calibrator bungu-0.212561 Å, obuhambisana ne-58 keV, ephakeme kakhulu kuneye-Cu Kα (8 keV) evame ukusetshenziswa njengomthombo we-X-ray welebhu. Isampula itholakala 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. Yonke idatha iqoqwe kusetshenziswa i-Perkin Elmer area detector, i-flat panel X-ray detector, amaphikseli angu-200 µm, 40×40 cm2 kusetshenziswa isikhathi sokuchayeka samasekhondi angu-0.3 namafreyimu angu-120.
Ukulinganiswa kwe-X-PEEM kwezinhlelo ezimbili zamamodeli ezikhethiwe kwenziwa esiteshini sokugcina se-Beamline MAXPEEM PEEM 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 somugqa we-beam sitholwe ngokulinganisa i-spectrum ye-ion yield esifundeni sokuvuselela kusukela ku-N 1 s kuya ku-1\(\pi _g^ \ast\) eduze kwe-hv = 401 eV ku-N2 ngokuncika kwamandla e-photon ku-E3/2, 57. Ama-spectra asondele anikeze i-ΔE (ububanzi bomugqa we-spectral) obungaba ngu-0.3 eV ebangeni lamandla elilinganisiwe. 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，通过使用带有1Si 120mm光栅的改进的SX-700 单色器用于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 , 使用 带有 带有 12 mm .改进 的 SX-700 单色器 于 于 用 用 用 Fe 2p L2.3 边缘、Cr 2p L2.3 边缘、Ni 2p L2.3 边缘和Ce M4.Ngakho-ke, uma usebenzisa i-monochromator ye-SX-700 eguquliwe ene-grating ye-Si engu-1200 line. 3, umphetho we-Cr 2p L2.3, umphetho we-Ni 2p L2.3 kanye nomphetho we-Ce M4.5.Skena amandla e-photon ngezinyathelo ezingu-0.2 eV. Kuwo wonke amandla, izithombe ze-PEEM zaqoshwa kusetshenziswa i-TVIPS F-216 CMOS detector ehlanganiswe ngefayibha enama-bin angu-2 x 2, enikeza isinqumo samaphikseli angu-1024 x 1024 ensimini yokubuka engu-20 µm. Isikhathi sokuvezwa kwezithombe sasingu-0.2 s, isilinganiso samafreyimu angu-16. Amandla esithombe se-photoelectron akhethwa ngendlela yokuthi anikeze isignali yesibili ephezulu kakhulu ye-electron. Zonke izilinganiso zenziwa ngokujwayelekile kusetshenziswa i-photon beam eqondile ehlanganisiwe. Ulwazi olwengeziwe mayelana nezilinganiso lungatholakala ocwaningweni lwangaphambilini. Ngemva kokufunda imodi yokuthola i-total electron yield (TEY) kanye nokusetshenziswa kwayo ku-X-PEEM49, ukujula kwesilingo sale ndlela kulinganiselwa ukuthi kungaba ngu-4-5 nm wesignali ye-Cr kanye no-6 nm we-Fe. Ukujula kwe-Cr kuseduze kakhulu nobukhulu befilimu ye-oxide (~4 nm)60,61 kuyilapho ukujula kwe-Fe kukhulu kunobukhulu. I-XRD eqoqwe emaphethelweni e-Fe L iyinhlanganisela ye-XRD yama-iron oxides kanye ne-Fe0 evela ku-matrix. Esimweni sokuqala, ukuqina kwama-electron akhishwayo kuvela kuzo 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 aye 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 kwama-electron, okunciphisa kakhulu impendulo ye-Fe0 spectral kumephu ye-iron XAS.
Ukuhlanganisa ukumbiwa kwedatha ku-data cube (idatha ye-X-PEEM) kuyisinyathelo esibalulekile ekukhipheni ulwazi olufanele (izakhiwo zamakhemikhali noma zomzimba) ngendlela enezilinganiso eziningi. Ukuhlanganiswa kwe-K-means kusetshenziswa kabanzi emikhakheni eminingana, kufaka phakathi umbono womshini, ukucubungula izithombe, ukuqashelwa kwephethini okungagadiwe, ubuhlakani bokwenziwa, kanye nokuhlaziywa kwezigaba. Isibonelo, ukuhlanganiswa kwe-K-means kusebenze kahle ekuhlanganisweni kwedatha yesithombe se-hyperspectral. Ngokomthetho, kwedatha enezici eziningi, i-algorithm ye-K-means ingazihlanganisa kalula ngokusekelwe olwazini mayelana nezimfanelo zazo (izakhiwo 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 kwensimbi ngesakhiwo esincane. I-algorithm ye-K-means ihlanganisa izigaba ezimbili: esigabeni sokuqala, kubalwa ama-centroid e-K, kanti esigabeni sesibili, iphuzu ngalinye linikezwa iqembu elinama-centroid angomakhelwane. Isikhungo sokudonsa amandla seqembu sichazwa njengesilinganiso sezibalo samaphuzu edatha (i-XAS spectrum) yalelo qembu. Kunebanga elihlukahlukene lokuchaza ama-centroid angomakhelwane njengebanga le-Euclidean. Ukuze uthole isithombe sokufaka se-px,y (lapho 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 ubulungu 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 yokugcina yekhwalithi yokuhlanganisa ihlobene kakhulu nokukhetha okungcono kakhulu kwama-centroid okuqala. Ngesakhiwo sedatha ye-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 nesithombe se-spectral ye-photon. energy. I-algorithm ye-K-means isetshenziselwa ukuhlola izifunda ezinesithakazelo kudatha ye-X-PEEM ngokuhlukanisa ama-pixel (ama-clusters noma ama-sub-blocks) ngokwezici zawo ze-spectral nokukhipha ama-centroid amahle kakhulu (amaphrofayili e-spectral e-XAS) e-analyte. cluster ngayinye). Isetshenziselwa ukutadisha ukusatshalaliswa kwendawo, izinguquko ze-spectral zendawo, ukuziphatha kwe-oxidation, kanye nezimo zamakhemikhali. 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 ezahlukene zamaqoqo e-K (izifunda zesakhiwo esincane) zihlolwe ukuthola amaqoqo nama-centroid afanele. Uma lezi zinombolo ziboniswa, amaphikseli aphinde abelwe kuma-centroid eqoqo afanele. Ukusatshalaliswa kombala ngakunye kuhambisana nendawo ephakathi kweqoqo, okubonisa ukuhlelwa kwendawo kwezinto zamakhemikhali noma zomzimba. Ama-centroid akhishwe ayinhlanganisela eqondile yama-spectra amsulwa.
Imininingwane esekela imiphumela yalolu cwaningo iyatholakala uma iceliwe ngokufanele kumbhali we-WC ofanele.
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