“Ukuguquka kwezakhi zofuzo kuyisihluthulelo sokwembula imfihlakalo yokuziphendukela kwemvelo. Indlela yokukhula isuka entweni elula kunazo zonke iye ezinhlobonhlobo zezinto eziphilayo ezihamba phambili ithatha izinkulungwane zeminyaka. Kodwa njalo eminyakeni eyizinkulungwane eziyikhulu kuba khona ukugxuma okubukhali phambili ekuziphendukeleni kwemvelo" (Charles Xavier, X-Men, 2000). Uma silahla zonke izinto eziqanjiwe zesayensi ezikhona kumahlaya namafilimu, amazwi kaProfesa X ayiqiniso impela. Ukuthuthukiswa kokuthile kuqhubeka ngokulinganayo isikhathi esiningi, kodwa ngezinye izikhathi kuba khona ukweqa okunomthelela omkhulu kuyo yonke inqubo. Lokhu akusebenzi nje kuphela ekuziphendukeleni kwezinhlobo zezilwane, kodwa nasekuziphendukeleni kwezobuchwepheshe, umshayeli oyinhloko okungabantu, ucwaningo lwabo kanye nezinto ezisunguliwe. Namuhla sizojwayelana nocwaningo, ngokusho kwababhali balo, ukugxuma kwangempela kokuziphendukela kwemvelo ku-nanotechnology. Ososayensi baseNorthwestern University (USA) bakwazi kanjani ukwakha i-heterostructure entsha enezinhlangothi ezimbili, kungani kwakhethwa i-graphene ne-borophene njengesisekelo, futhi yiziphi izakhiwo okungenzeka uhlelo olunjalo lube nazo? Umbiko weqembu locwaningo uzositshela ngalokhu. Hamba.
Isisekelo socwaningo
Sizwe igama elithi “graphene” izikhathi eziningi, liwukuguqulwa kwekhabhoni enezinhlangothi ezimbili, okuhlanganisa ungqimba lwe-athomu ye-carbon 1 athomu. Kodwa "borofen" ayivelakancane kakhulu. Leli gama lisho ikristalu enezinhlangothi ezimbili ehlanganisa kuphela ama-athomu e-boron (B). Amathuba okuba khona kwe-borophene kwabikezelwa okokuqala emuva maphakathi nawo-90, kodwa ngokusebenza lesi sakhiwo satholwa kuphela ngo-2015.
Isakhiwo se-athomu se-borophene siqukethe izakhi ezingunxantathu nezinezinhlangothi ezine futhi siwumphumela wokusebenzelana phakathi kwamabhondi endiza aphakathi nendawo naphakathi nendawo, okujwayelekile kakhulu ezintweni ezingenawo ama-electron, afaka i-boron.
*Ngamabhondi aphakathi nendawo namakhulu sisho amabhondi amakhemikhali - ukusebenzisana kwama-athomu okubonisa ukuzinza kwe-molecule noma ikristalu njengesakhiwo esisodwa. Isibonelo, ibhondi yama-electron amabili ephakathi nendawo yenzeka lapho ama-athomu angu-2 ehlanganyela ama-electron angu-2, futhi ibhondi yama-electron amathathu ephakathi nendawo yenzeka lapho ama-athomu angu-2 nama-electron angu-3, njll.
Ngokombono womzimba, i-borophene ingase ibe namandla futhi iguquguquke kakhulu kune-graphene. Kuphinde kukholakala ukuthi izakhiwo ze-borophene zingaba umphelelisi ophumelelayo wamabhethri ngoba i-borophene inomthamo othize ophezulu kanye ne-electronic conductivity eyingqayizivele kanye nezindawo zokuthutha ze-ion. Nokho, okwamanje lokhu kuwumbono nje.
Ukuba i-trivalent element*, i-boron inama-10 okungenani i-allotropes*. Ngefomu elinezinhlangothi ezimbili, ezifanayo i-polymorphism* kuyabhekwa futhi.
Isici se-Trivalent* ekwazi ukwenza izibopho ezintathu ze-covalent, i-valency yayo emithathu.
I-Allotropy* - lapho isakhi samakhemikhali esisodwa singavezwa ngesimo sezinto ezimbili noma ngaphezulu ezilula. Ngokwesibonelo, carbon - diamond, graphene, graphite, carbon nanotubes, njll.
I-Polymorphism* - ikhono lento yokuba khona ezakhiweni ezihlukene zekristalu (ukuguqulwa kwe-polymorphic). Endabeni yezinto ezilula, leli gama lifana ne-allotropy.
Uma kubhekwa le-polymorphism ebanzi, kuphakanyiswa ukuthi i-borophene ingase ibe ikhandidethi elihle kakhulu lokudala i-heterostructures entsha enezinhlangothi ezimbili, njengoba ukulungiselelwa okuhlukene kwebhoron kufanele kuxegise izidingo zokumataniswa kwe-lattice. Ngeshwa, lolu daba luke lwafundwa ngokukhethekile ezingeni letiyori ngenxa yobunzima bokuhlanganisa.
Okwezinto ezijwayelekile ze-2D ezitholwe kumakristalu anezingqimba ngobuningi, ama-heterostructures aqondile angenziwa kusetshenziswa ukupakishwa komshini. Ngakolunye uhlangothi, ama-heterostructures asemaceleni anezinhlangothi ezimbili asekelwe ekuhlanganiseni okusuka phansi kuya phezulu. I-Atomically lateral heterostructures yangemuva inamandla amakhulu ekuxazululeni izinkinga zokulawula ukusebenza kwe-heterojunction, nokho, ngenxa yokuhlangana okuhlangene, ukufaniswa kwe-lattice okungaphelele ngokuvamile kubangela ukuxhumana okubanzi nokuphazamisekile. Ngakho-ke, kukhona okungenzeka, kodwa kukhona nezinkinga ekukuboneni.
Kulo msebenzi, abacwaningi bakwazi ukuhlanganisa i-borophene ne-graphene ibe yi-heterostructure eyodwa enezinhlangothi ezimbili. Naphezu kokungafani kwe-crystallographic lattice kanye nokulinganisa phakathi kwe-borophene ne-graphene, ukubekwa ngokulandelana kwe-carbon ne-boron ku-Ag(111) substrate ngaphansi kwe-ultra-high vacuum (UHV) kuphumela cishe ku-atomically lateral heterointerfaces nokuqondanisa kwe-lattice okubikezelwe, kanye nokuqondanisa kwe-heteroyo okuvundlile. .
Ukulungiselela ucwaningo
Ngaphambi kokutadisha i-heterostructure, kwakudingeka yenziwe. Ukukhula kwe-graphene ne-borophene kwenziwa ekamelweni le-vacuum ephezulu kakhulu ngengcindezi ye-1x10-10 millibars.
I-single crystal Ag(111) substrate yahlanzwa imijikelezo ephindaphindiwe ye-Ar+ sputtering (1 x 10-5 millibar, 800 eV, imizuzu engu-30) kanye ne-thermal annealing (550 °C, imizuzu engu-45) ukuze kutholwe i-Ag ehlanzekile nephansi 111).
I-graphene yakhuliswa ukuhwamuka kwe-electron beam ye-graphite rod emsulwa (99,997%) enobubanzi obungu-2.0 mm ku-Ag (750) substrate eshisiswe yaba ngu-111 °C endaweni yokushisisa engu-~ 1.6 A kanye nevolthi esheshayo engu-~ 2 kV , enikeza amandla akhona angu-~ 70 mA kanye ne-carbon flux ~40 nA. Ukucindezela ekamelweni kwakuyi-1 x 10-9 millibars.
I-Borophene yakhuliswa ngokuhwamuka kwe-electron beam ye-boron rod ehlanzekile (99,9999%) ku-submonolayer graphene ku-Ag (400) eshisiselwe ku-500-111 °C. I-filament current ibingu-~1.5 A kanti amandla kagesi asheshayo abe ngu-1.75 kV, okunikeza amandla akhona angu-~34 mA kanye ne-boron flux engu-~10 nA. Ukucindezela ekamelweni ngesikhathi sokukhula kwe-borophene kwakucishe kube yi-2 x 10-10 millibars.
Imiphumela yocwaningo
Isithombe #1
Esithombeni I-1A kukhonjisiwe I-STM* isifinyezo se-graphene esikhulile, lapho izizinda ze-graphene zibonwa kangcono kusetshenziswa imephu dI/dV (I-1B), lapho I и V kukhona umhubhe wamanje kanye nokususwa kwesampula, futhi d - ukuminyana.
I-STM* - ukuskena isibonakhulu sokushunqa.
dI/dV amamephu wesampula asivumele ukuthi sibone ukuminyana okuphezulu kwendawo kwezifunda ze-graphene uma kuqhathaniswa ne-substrate ye-Ag(111). Ngokuhambisana nezifundo zangaphambilini, isimo esingaphezulu se-Ag (111) sinesimo sesinyathelo, esishintshelwe emandleni amahle dI/dV i-spectrum ye-graphene (I-1С), echaza ukuminyana okuphezulu kwendawo kwezifunda ze-graphene ku I-1B kwe 0.3ev.
Esithombeni 1D singabona isakhiwo se-graphene yongqimba olulodwa, lapho i-lattice yekhekhe lezinyosi kanye i-moiré superstructure*.
Superstructure* - isici sesakhiwo senhlanganisela yekristalu esiphinda ngesikhathi esithile futhi ngaleyo ndlela sidale isakhiwo esisha esinenkathi ehlukile yokushintshanisa.
Moire* - Ukuma okuphezulu kwamaphethini amabili anezikhala ezikhathi ezithile phezu kwelinye.
Emazingeni okushisa aphansi, ukukhula kuholela ekwakhekeni kwezizinda ze-dendritic kanye ne-graphene ezingasebenzi. Ngenxa yokusebenzelana okubuthakathaka phakathi kwe-graphene ne-substrate engaphansi, ukuqondanisa okujikelezayo kwe-graphene ngokuphathelene ne-Ag(111) engaphansi akuyona into ehlukile.
Ngemuva kokufakwa kwe-boron, ukuskena i-microscope yokuthungatha (1E) ibonise ukuba khona kwenhlanganisela yezizinda ze-borophene ne-graphene. Okunye okubonakalayo esithombeni yizifunda ezingaphakathi kwe-graphene, kamuva eziye zahlonzwa njenge-graphene ehlanganiswe ne-borophene (ekhonjiswe esithombeni. Gr/B). Izakhi zomugqa eziqondiswe ezikhombisi-ndlela ezintathu futhi zihlukaniswa nge-engeli engu-120° nazo zibonakala ngokucacile kule ndawo (imicibisholo ephuzi).
Isithombe #2
Isithombe sivuliwe I-2Afuthi 1E, qinisekisa ukubukeka kokucindezeleka okumnyama kwendawo ku-graphene ngemva kokufakwa kwe-boron.
Ukuze uhlole kangcono lezi zakhiwo futhi uthole umsuka wazo, esinye isithombe sathathwa endaweni efanayo, kodwa kusetshenziswa amamephu |dlnI/dz| (2B), lapho I - umhubhe wamanje, d ukuminyana, futhi z - ukuhlukaniswa kwesampula ye-probe (igebe phakathi kwenaliti yesibonakhulu kanye nesampula). Ukusetshenziswa kwale ndlela kwenza kube nokwenzeka ukuthola izithombe ezinesinqumo esiphezulu sendawo. Ungasebenzisa futhi i-CO noma i-H2 enalithi yesibonakhulu kulokhu.
Isithombe I-2С isithombe esitholwe kusetshenziswa i-STM ithiphu layo lalimbozwe nge-CO. Ukuqhathaniswa kwezithombe А, В и С ikhombisa ukuthi zonke izakhi ze-athomu zichazwa njengamaheksagoni amathathu agqamile ancikene aqondiswe ezinhlangothini ezimbili ezingalingani (onxantathu obomvu nabaphuzi ezithombeni).
Izithombe ezikhulisiwe zale ndawo (2D) qinisekisa ukuthi lezi zakhi zivumelana nokungcola kwe-boron dopant, ezithatha ama-graphene sublattices amabili, njengoba kuboniswa izakhiwo ezibekwe phezulu.
Ukufakwa kwe-CO enaliti yesibonakhulu kwenze kwaba nokwenzeka ukuveza ukwakheka kwejiyomethri yeshidi le-borophene (2E), okungeke kwenzeke uma inaliti yayijwayelekile (insimbi) ngaphandle kwe-CO coating.
Isithombe #3
Ukwakhiwa kwama-heterointerfaces angemuva phakathi kwe-borophene ne-graphene (I-3A) kufanele yenzeke lapho i-borophene ikhula eduze nezizinda ze-graphene esezivele zine-boron.
Ososayensi bakhumbuza ukuthi i-lateral heterointerfaces esekelwe ku-graphene-hBN (graphene + boron nitride) inokungaguquguquki kwe-lattice, futhi ama-heterojunctions asekelwe kunguquko ye-dichalcogenides yensimbi inokungaguquguquki kwe-symmetry. Endabeni ye-graphene/borophene, isimo sihluke kancane - banokufana okuncane kwesakhiwo ngokuya nge-lattice constants noma i-crystal symmetry. Nokho, ngaphandle kwalokhu, i-graphene/borophene heterointerface engemuva ibonisa ukuvumelana okucishe kufane kwe-athomu, nezikhombisi-ndlela zomugqa we-boron (B-row) ziqondaniswe nezikhombisi-ndlela ze-zigzag (ZZ) zegraphene (I-3A) Use I-3B isithombe esikhulisiwe sesifunda se-ZZ se-heterointerface siyaboniswa (imigqa eluhlaza okwesibhakabhaka ibonisa izakhi ezihlangene ezihambisana ne-boron-carbon covalent bond).
Njengoba i-borophene ikhula ngezinga lokushisa eliphansi uma iqhathaniswa ne-graphene, imiphetho yesizinda se-graphene cishe ayinakwenzeka ukuhamba okuphezulu lapho yenza i-heterointerface ene-borophene. Ngakho-ke, i-heterointerface ecishe inembe nge-athomu kungenzeka iwumphumela wokucushwa okuhlukile nezici zamabhondi e-boron amaningi. Ukuskena umhubhe we-spectroscopy spectra (I-3С) kanye nokuhanjiswa komhubhe okuhlukile (3D) bonisa ukuthi uguquko lwe-elekthronikhi lusuka ku-graphene luye ku-borophene lwenzeka ebangeni elingu-~5 Å ngaphandle kokusebenzelana okubonakalayo kwezimo.
Esithombeni 3E Kuboniswa izibukeli ezintathu zokuskena ze-spectroscopy ezithathwe emigqeni emithathu edayishiwe ku-3D, okuqinisekisa ukuthi lolu shintsho olufushane lwe-elekthronikhi aluzweli ezakhiweni zendawo ezihlangene futhi luqhathaniswa nalolo oluse-borophene-silver interfaces.
Isithombe #4
I-graphene ukuxhumana* nayo ifundwe kabanzi ngaphambilini, kodwa ukuguqulwa kwama-intercalants abe amashidi eqiniso e-2D akuvamile.
I-intercalation* - ukufakwa okubuyiselekayo kwe-molecule noma iqembu lama-molecule phakathi kwamanye ama-molecule noma amaqembu ama-molecule.
Iradiyasi encane ye-athomu ye-boron nokusebenzisana okubuthakathaka phakathi kwegraphene ne-Ag(111) kuphakamisa ukuhlobana okungaba khona kwegraphene ne-boron. Esithombeni I-4A ubufakazi abuvezwa nje kuphela ngokuhlangana kwe-boron, kodwa futhi nokwakhiwa kwe-borophene-graphene heterostructures eqondile, ikakhulukazi izizinda ezingunxantathu ezizungezwe i-graphene. I-lattice yekhekhe lezinyosi ebonwa kulesi sizinda esingunxantathu iqinisekisa ukuba khona kwe-graphene. Kodwa-ke, le graphene ibonisa ukuminyana okuphansi kwendawo yezifunda ku--50 meV uma kuqhathaniswa ne-graphene ezungezile (I-4B). Uma kuqhathaniswa ne-graphene ngqo ku-Ag(111), abukho ubufakazi bokuminyana okuphezulu kwasendaweni kwezifunda ku-spectrum. dI/dV (4C, ijika eliluhlaza okwesibhakabhaka), elihambisana nesimo esiphezulu se-Ag(111), siwubufakazi bokuqala bokuhlangana kwe-boron.
Futhi, njengoba kulindelekile ekuxhumaneni okuyingxenye, i-graphene lattice ihlala iqhubekayo kuyo yonke i-interface yangemuva phakathi kwe-graphene nesifunda esingunxantathu (4D - ihambisana nendawo engunxande I-4A, zizungezwe ngomugqa wamachashazi obomvu). Isithombe esisebenzisa i-CO enaliti yesibonakhulu siphinde saqinisekisa ubukhona bokungcola okufaka esikhundleni se-boron (4E - ihambisana nendawo engunxande I-4A, zizungezwe ngomugqa wamachashazi aphuzi).
Izinaliti zeMicroscope ngaphandle kwanoma yikuphi ukunamathela nazo zasetshenziswa ngesikhathi sokuhlaziya. Kulokhu, izimpawu zezakhi zomugqa ezinohlangothi olulodwa ezine-periodicity ye-5 Å zembulwa ezizindeni ze-graphene ezihlanganisiwe (4F и 4G). Lezi zakhiwo ezinohlangothi olulodwa zifana nemigqa ye-boron kumodeli ye-borophene. Ngokungeziwe kusethi yamaphoyinti ahambisana ne-graphene, uguquko lwe-Fourier lwesithombe lube 4G Ibonisa ipheya yamaphuzu we-orthogonal ahambisana neletiyela elingunxande elingu-3 Å x 5 Å (4H), okuvumelana kahle kakhulu nemodeli ye-borophene. Ngaphezu kwalokho, umumo okathathu ophawuliwe wohlu lwezakhi zomugqa (1E) ivumelana kahle nesakhiwo esifanayo esivelele esiqashelwa amashidi e-borophene.
Konke lokhu kuqashelwa kuphakamisa ngokuqinile ukuhlangana kwe-graphene nge-borophene eduze konqenqema lwe-Ag, okuholela ekwakhekeni kwe-borophene–graphene heterostructures eqondile, engabonakala ngokunenzuzo ngokwandisa ukumbozwa kokuqala kwe-graphene.
4I iwumfanekiso ongokomfanekiso we-heterostructure eqondile evuliwe 4H, lapho isiqondiso somugqa we-boron (umcibisholo obomvana) siqondaniswe eduze nesiqondisindlela esimazombezombe segraphene (umcibisholo omnyama), ngaleyo ndlela kwakheka i-heterostructure eqondile ejikelezayo.
Ukuze uthole ulwazi oluningiliziwe ngama-nuances ocwaningo, ngincoma ukubheka и kuyena.
Epilogue
Lolu cwaningo lubonise ukuthi i-borophene ikwazi ngempela ukwenza ama-heterostructures asemaceleni naqondile nge-graphene. Amasistimu anjalo angasetshenziswa ekuthuthukiseni izinhlobo ezintsha zezakhi ezimbili-dimensional ezisetshenziswa ku-nanotechnology, i-electronic flexible and wearable electronics, kanye nezinhlobo ezintsha zama-semiconductors.
Abacwaningi ngokwabo bakholelwa ukuthi ukuthuthuka kwabo kungaba ukuqhubekela phambili okunamandla kobuchwepheshe obuhlobene nogesi. Nokho, kusenzima ukusho ngokuqinisekile ukuthi amazwi abo ayoba isiprofetho. Okwamanje, kusekuningi okusamele kucwaningwe, kuqondwe futhi kusungulwe ukuze leyo mibono eqanjiwe yesayensi egcwalisa izingqondo zososayensi ibe yiqiniso eligcwele.
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Source: www.habr.com