“Kev hloov pauv yog tus yuam sij rau kev nthuav tawm qhov tsis meej ntawm evolution. Txoj kev ntawm txoj kev loj hlob los ntawm cov kab mob yooj yim tshaj plaws mus rau cov hom kab mob tseem ceeb yuav kav ntau txhiab xyoo. Tab sis txhua 2000 xyoo muaj ib tug ntse dhia mus rau hauv evolution" (Charles Xavier, X-Men, XNUMX). Yog hais tias peb muab pov tseg tag nrho cov ntsiab lus science-fiction muaj nyob rau hauv comics thiab films, ces cov lus ntawm xib fwb X yog tiag tiag. Txoj kev loj hlob ntawm ib yam dab tsi ua tau zoo sib xws feem ntau ntawm lub sijhawm, tab sis qee zaum muaj kev dhia uas muaj kev cuam tshuam loj rau tag nrho cov txheej txheem. Qhov no siv tsis tau tsuas yog rau evolution ntawm hom, tab sis kuj mus rau evolution ntawm technology, lub ntsiab tsav tsheb uas yog tib neeg, lawv cov kev tshawb fawb thiab inventions. Niaj hnub no peb yuav tau paub nrog ib txoj kev tshawb no, raws li nws cov sau phau ntawv, yog ib tug tiag tiag evolutionary leap nyob rau hauv nanotechnology. Cov kws tshawb fawb los ntawm Northwestern University (Tebchaws USA) tau tswj hwm li cas los tsim cov txheej txheem tshiab ob sab, vim li cas graphene thiab borophene tau xaiv los ua lub hauv paus, thiab cov khoom zoo li no yuav muaj li cas? Daim ntawv tshaj tawm ntawm pab pawg tshawb fawb yuav qhia peb txog qhov no. Mus.
Kev tshawb fawb hauv paus
Peb tau hnov lo lus "graphene" ntau zaus; nws yog kev hloov kho ob sab ntawm cov pa roj carbon monoxide, uas muaj cov txheej txheem carbon atoms 1 atom tuab. Tab sis "borofen" yog qhov tsawg kawg nkaus. Lub sij hawm no yog hais txog ob lub ntsej muag siv lead ua uas tsuas yog boron (B) atoms. Qhov muaj peev xwm ntawm qhov muaj nyob ntawm borophene yog thawj zaug kwv yees rov qab rau hauv nruab nrab-90s, tab sis hauv kev xyaum nws muaj peev xwm tau txais cov qauv no tsuas yog los ntawm 2015.
Cov qauv atomic ntawm borophene muaj cov duab peb sab thiab hexagonal thiab yog qhov tshwm sim ntawm kev sib cuam tshuam ntawm ob-center thiab multi-center hauv-plane bonds, uas yog qhov zoo heev rau cov khoom tsis muaj hluav taws xob, uas suav nrog boron.
*Los ntawm ob-center thiab multicenter bonds peb txhais tau hais tias tshuaj bonds - kev sib cuam tshuam ntawm atoms uas characterize lub stability ntawm ib tug molecule los yog siv lead ua raws li ib tug qauv. Piv txwv li, ob lub hauv nruab nrab ob-electron daim ntawv cog lus tshwm sim thaum 2 atoms sib koom 2 electrons, thiab ob-center peb-electron bond tshwm sim thaum 2 atoms thiab 3 electrons, thiab lwm yam.
Los ntawm qhov pom ntawm lub cev, borophene yuav muaj zog thiab hloov tau ntau dua li graphene. Nws kuj tseem ntseeg tau tias cov qauv borophene tuaj yeem ua tau zoo ntxiv rau cov roj teeb, vim borophene muaj peev xwm tshwj xeeb thiab cov khoom siv hluav taws xob tshwj xeeb thiab cov khoom thauj ion. Txawm li cas los xij, lub sijhawm no tsuas yog kev xav xwb.
Ua trivalent element *, boron muaj tsawg kawg yog 10 allotropes *. Nyob rau hauv ob-dimensional daim ntawv, zoo sib xws polymorphism * kuj pom.
Trivalent element * muaj peev xwm tsim peb covalent bonds, lub valency ntawm uas yog peb.
Allotropy * - thaum ib qho tshuaj lom neeg tuaj yeem nthuav tawm hauv daim ntawv ntawm ob lossis ntau dua cov tshuaj yooj yim. Piv txwv li, carbon - pob zeb diamond, graphene, graphite, carbon nanotubes, thiab lwm yam.
Polymorphism * - lub peev xwm ntawm cov khoom muaj nyob hauv cov qauv siv lead ua sib txawv (polymorphic hloov kho). Nyob rau hauv cov ntaub ntawv ntawm tej yam yooj yim, lo lus no yog synonymous nrog allotropy.
Muab qhov dav polymorphism no, nws tau pom tias borophene yuav yog ib tus neeg sib tw zoo tshaj plaws rau kev tsim cov txheej txheem ob-dimensional heterostructures, txij li cov txheej txheem sib txawv ntawm cov boron sib txuas yuav tsum tau ua kom lub lattice sib phim. Hmoov tsis zoo, qhov teeb meem no yav dhau los tau kawm tshwj xeeb ntawm qib theoretical vim muaj teeb meem hauv kev sib txuas.
Rau cov pa 2D cov ntaub ntawv tau los ntawm cov txheej txheem ntau lawm, ntsug heterostructures tuaj yeem pom tau tias siv tshuab stacking. Ntawm qhov tod tes, ob-dimensional lateral heterostructures yog nyob rau hauv qab-up synthesis. Atomically precision lateral heterostructures muaj peev xwm daws tau qhov teeb meem ntawm kev ua haujlwm ntawm heterojunction, txawm li cas los xij, vim yog covalent sib txuas, cov lattice tsis zoo sib xws feem ntau ua rau muaj kev cuam tshuam dav thiab cuam tshuam. Yog li ntawd, muaj peev xwm, tab sis kuj muaj teeb meem hauv kev paub txog nws.
Hauv kev ua haujlwm no, cov kws tshawb fawb tau tswj hwm kev sib koom ua ke ntawm borophene thiab graphene rau hauv ib qho ntawm ob sab heterostructure. Txawm hais tias crystallographic lattice mismatch thiab symmetry ntawm borophene thiab graphene, sequential deposition ntawm carbon thiab boron mus rau ib tug Ag (111) substrate nyob rau hauv ultra-high nqus (UHV) ua rau ze li ntawm atomically meej lateral heterointerfaces nrog kwv yees lattice alignments, as Well as vertical heteroface. .
Kev npaj kawm
Ua ntej kawm txog heterostructure, nws yuav tsum tau tsim. Kev loj hlob ntawm graphene thiab borophene yog nqa tawm nyob rau hauv ib tug ultra-high nqus chamber nrog ib tug siab ntawm 1x10-10 millibars.
Ib leeg siv lead ua Ag(111) substrate raug ntxuav los ntawm kev rov ua dua ntawm Ar + sputtering (1 x 10-5 millibar, 800 eV, 30 feeb) thiab thermal annealing (550 ° C, 45 feeb) kom tau txais ib qho atomically huv thiab tiaj tus Ag ( 111) Ib..
Graphene yog zus los ntawm electron beam evaporation ntawm ib tug ntshiab (99,997%) graphite pas nrig nrog ib txoj kab uas hla ntawm 2.0 hli mus rau ib tug Ag (750) substrate rhuab mus rau 111 ° C ntawm lub cua sov tam sim no ntawm ~ 1.6 A thiab ib tug accelerating voltage ntawm ~ 2 kV. , uas muab emission tam sim no ntawm ~ 70 mA thiab carbon flux ~ 40 nA. Lub siab nyob rau hauv lub chamber yog 1 x 10-9 millibars.
Borophene tau zus los ntawm electron beam evaporation ntawm ib tug ntshiab (99,9999%) boron pas nrig mus rau submonolayer graphene ntawm Ag (400) rhuab mus rau 500-111 ° C. Lub filament tam sim no yog ~ 1.5 A thiab qhov nrawm nrawm yog 1.75 kV, uas muab cov emission tam sim no ntawm ~ 34 mA thiab boron flux ntawm ~ 10 nA. Lub siab nyob rau hauv lub chamber thaum lub sij hawm loj hlob ntawm borophene yog kwv yees li 2 x 10-10 millibars.
Cov txiaj ntsig tshawb fawb
Duab #1
Ntawm daim duab 1A muaj qhia STM* snapshot ntawm zus graphene, qhov twg graphene domains yog qhov zoo tshaj plaws pom tau siv daim ntawv qhia dI/dV (1B), qhov twg I и V yog cov tunneling tam sim no thiab cov qauv xa tawm, thiab d - qhov ceev.
STM* - scanning tunneling microscope.
dI/dV Daim duab qhia chaw ntawm cov qauv tso cai rau peb kom pom qhov ntom ntom ntawm cov xeev ntawm graphene piv rau Ag(111) substrate. Raws li kev tshawb fawb yav dhau los, lub xeev saum npoo ntawm Ag (111) muaj cov yam ntxwv ntawm cov kauj ruam, hloov mus rau lub zog zoo los ntawm dI/dV spectrum ntawm graphene (1S), uas piav qhia qhov siab dua hauv zos ntawm cov xeev ntawm graphene rau 1B ua 0.3v.
Ntawm daim duab 1D peb tuaj yeem pom cov qauv ntawm ib txheej graphene, qhov twg honeycomb lattice thiab moiré superstructure *.
Superstructure * - ib qho tshwj xeeb ntawm cov qauv ntawm cov crystalline compound uas rov ua dua ntawm qee lub sijhawm thiab yog li tsim cov qauv tshiab nrog lub sijhawm sib txawv.
Moire* - superposition ntawm ob lub sij hawm mesh qauv nyob rau sab saum toj ntawm ib leeg.
Thaum qhov kub thiab txias, kev loj hlob ua rau tsim cov dendritic thiab tsis zoo graphene domains. Vim muaj kev cuam tshuam tsis muaj zog ntawm graphene thiab lub hauv paus substrate, kev sib hloov ntawm graphene nrog rau cov hauv paus Ag(111) tsis yog tshwj xeeb.
Tom qab boron deposition, scanning tunneling microscopy (1E) pom tias muaj kev sib xyaw ntawm borophene thiab graphene domains. Kuj pom hauv daim duab yog cov cheeb tsam hauv graphene, uas tom qab ntawd tau txheeb xyuas tias graphene intercalated nrog borophene (qhia hauv daim duab. G/B). Linear ntsiab lus taw qhia nyob rau hauv peb cov lus qhia thiab sib cais los ntawm lub kaum sab xis ntawm 120 ° kuj pom meej hauv cheeb tsam no (cov xub daj).
Duab #2
Duab nyob rau 2Ali qub 1E, paub meej tias qhov tshwm sim ntawm kev nyuaj siab nyob rau hauv graphene tom qab boron deposition.
Txhawm rau txhawm rau tshuaj xyuas cov kev tsim no zoo dua thiab pom lawv cov keeb kwm, lwm daim duab raug coj los ntawm tib cheeb tsam, tab sis siv cov duab qhia chaw |dlnI/dz| (2B), qhov twg I - tunnel tam sim no, d yog qhov ceev, thiab z - kev sojntsuam-cov qauv sib cais (qhov sib txawv ntawm lub koob tsom iav thiab cov qauv). Kev siv cov txheej txheem no ua rau nws tuaj yeem tau txais cov duab nrog kev daws teeb meem siab. Koj tseem tuaj yeem siv CO lossis H2 ntawm lub koob txhaj tshuaj rau qhov no.
Image Duab 2S yog ib daim duab tau siv STM uas nws lub taub hau coated nrog CO. Kev sib piv ntawm cov duab А, В и С qhia tau hais tias tag nrho cov ntsiab lus atomic txhais tau tias yog peb lub teeb hexagons uas nyob ib sab uas tau qhia nyob rau hauv ob qho kev qhia tsis sib xws (daim duab peb sab liab thiab daj hauv daim duab).
Cov duab loj ntawm thaj chaw no (2D) paub meej tias cov ntsiab lus no tau pom zoo nrog boron dopant impurities, tuav ob lub graphene sublattices, raws li qhia los ntawm cov qauv superimposed.
CO txheej ntawm rab koob tsom iav tau ua kom pom cov qauv geometric ntawm daim ntawv borophene (2E), uas yuav ua tsis tau yog tias rab koob yog tus qauv (hlau) tsis muaj CO txheej.
Duab #3
Tsim ntawm lateral heterointerfaces ntawm borophene thiab graphene (3A) yuav tsum tshwm sim thaum borophene loj hlob ib sab ntawm graphene domains uas twb muaj boron.
Cov kws tshawb fawb nco ntsoov tias lateral heterointerfaces raws li graphene-hBN (graphene + boron nitride) muaj lattice sib xws, thiab heterojunctions raws li kev hloov pauv hlau dichalcogenides muaj symmetry sib xws. Nyob rau hauv cov ntaub ntawv ntawm graphene / borophene, qhov teeb meem yog me ntsis txawv - lawv muaj tsawg yam ntxwv zoo sib xws nyob rau hauv cov nqe lus ntawm lattice tas li los yog siv lead ua symmetry. Txawm li cas los xij, txawm li cas los xij, qhov graphene sab nraud / borophene heterointerface qhia tau hais tias yuav luag zoo meej atomic sib xws, nrog cov kab boron (B-kab) cov lus qhia ua raws li cov lus qhia zigzag (ZZ) ntawm graphene (3A) Nyob rau 3B daim duab loj ntawm ZZ cheeb tsam ntawm heterointerface tau qhia (cov kab xiav qhia cov ntsiab lus sib txuas nrog boron-carbon covalent bonds).
Txij li thaum borophene loj hlob ntawm qhov kub qis dua piv rau graphene, cov npoo ntawm cov graphene tsis zoo li yuav muaj kev txav mus los siab thaum tsim cov heterointerface nrog borophene. Yog li ntawd, qhov ze li ntawm atomically meej heterointerface yog qhov tshwm sim ntawm kev teeb tsa sib txawv thiab cov yam ntxwv ntawm cov ntawv cog lus boron multisite. Scanning tunneling spectroscopy spectra (3S) thiab qhov sib txawv ntawm qhov conductivity (3D) qhia tau hais tias kev hloov hluav taws xob los ntawm graphene mus rau borophene tshwm sim dhau qhov deb ntawm ~ 5 Å uas tsis pom qhov cuam tshuam.
Ntawm daim duab 3E Pom tau yog peb qhov scanning tunneling spectroscopy spectra coj raws li peb txoj kab dashed hauv 3D, uas paub meej tias qhov kev hloov hluav taws xob luv luv no tsis zoo rau cov qauv hauv zos thiab sib piv rau qhov ntawm borophene-silver interfaces.
Duab #4
Graphene intercalation * yav dhau los kuj tau kawm dav dav, tab sis kev hloov pauv ntawm intercalants rau hauv cov nplooj ntawv 2D tseeb yog qhov tsawg.
Intercalation * - thim rov qab suav nrog cov molecule lossis pawg molecules ntawm lwm cov molecules lossis pawg ntawm cov molecules.
Lub atomic vojvoog me me ntawm boron thiab kev sib cuam tshuam tsis muaj zog ntawm graphene thiab Ag(111) qhia tau tias muaj peev xwm intercalation ntawm graphene nrog boron. Hauv daim duab 4A Cov pov thawj tau nthuav tawm tsis yog ntawm boron intercalation nkaus xwb, tab sis kuj ntawm kev tsim ntawm ntsug borophene-graphene heterostructures, tshwj xeeb tshaj yog cov duab peb sab uas nyob ib puag ncig los ntawm graphene. Honeycomb lattice pom nyob rau hauv daim duab peb sab no paub meej tias muaj graphene. Txawm li cas los xij, qhov graphene no nthuav tawm qhov qis qis hauv lub xeev ntawm -50 meV piv rau ib puag ncig graphene (4B). Muab piv rau graphene ncaj qha rau Ag(111), tsis muaj pov thawj ntawm cov xeev siab ntawm cov xeev hauv spectrum. dI/dV (4C, xiav nkhaus), sib xws rau Ag(111) nto xeev, yog thawj cov pov thawj ntawm boron intercalation.
Tsis tas li ntawd, raws li xav tau rau ib nrab intercalation, lub graphene lattice tseem txuas ntxiv mus thoob plaws lub lateral interface ntawm graphene thiab daim duab peb sab (4D - sib raug mus rau ib cheeb tsam nyob rau 4A, ncig hauv kab liab dotted). Ib daim duab uas siv CO ntawm lub koob txhaj tshuaj microscope kuj tau lees paub tias muaj boron hloov impurities (4E - sib raug mus rau ib cheeb tsam nyob rau 4A, voj voog nyob rau hauv daj dotted kab).
Microscope koob tsis muaj txheej txheem kuj tau siv thaum lub sij hawm tsom xam. Nyob rau hauv cov ntaub ntawv no, cov cim qhia ntawm ib-dimensional linear ntsiab nrog ib tug periodicity ntawm 5 Å tau tshwm sim nyob rau hauv lub intercalated graphene domains (4F и 4G). Cov qauv ib-dimensional no zoo li cov kab boron hauv cov qauv borophene. Ntxiv nrog rau cov txheej txheem ntawm cov ntsiab lus sib xws rau graphene, Fourier hloov pauv ntawm daim duab rau hauv 4G qhia ib khub ntawm orthogonal cov ntsiab lus sib raug rau ib tug 3 Å x 5 Å rectangular lattice (4 H ua), uas yog nyob rau hauv kev pom zoo zoo nrog cov qauv borophene. Tsis tas li ntawd, qhov pom triple orientation ntawm array ntawm linear ntsiab (1E) pom zoo nrog tib lub qauv tseem ceeb uas tau pom zoo rau cov nplooj ntawv borophene.
Tag nrho cov kev soj ntsuam no qhia tau hais tias kev sib cuam tshuam ntawm graphene los ntawm borophene nyob ze ntawm cov npoo ntawm Ag, uas yog li ua rau kev tsim ntawm ntsug borophene-graphene heterostructures, uas tuaj yeem ua tau zoo dua los ntawm kev nce qhov pib ntawm graphene.
4I yog ib tug schematic sawv cev ntawm ib tug ntsug heterostructure rau 4H, qhov twg cov kev taw qhia ntawm boron kab (paj liab) yog zoo sib xws nrog zigzag kev taw qhia ntawm graphene (dub xub), yog li tsim ib tug rotationally proportional ntsug heterostructure.
Rau cov ncauj lus kom ntxaws ntxiv nrog cov nuances ntawm txoj kev tshawb no, kuv xav kom saib и rau nws.
Epilogue
Txoj kev tshawb no qhia tau hais tias borophene muaj peev xwm tsim cov lateral thiab ntsug heterostructures nrog graphene. Cov tshuab zoo li no tuaj yeem siv rau hauv kev tsim cov khoom tshiab ntawm ob lub ntsiab lus siv hauv nanotechnology, hloov tau yooj yim thiab siv tau hluav taws xob, nrog rau hom tshiab ntawm semiconductors.
Cov kws tshawb fawb lawv tus kheej ntseeg tias lawv txoj kev loj hlob tuaj yeem yog lub zog thawb rau pem hauv ntej rau kev siv tshuab hluav taws xob. Txawm li cas los xij, nws tseem nyuaj rau hais kom paub tseeb tias lawv cov lus yuav dhau los ua yaj saub. Tam sim no, tseem muaj ntau yam uas yuav tsum tau tshawb fawb, nkag siab thiab tsim kom muaj cov tswv yim kev tshawb fawb txog kev tshawb fawb uas ua rau cov kws tshawb fawb hauv siab dhau los ua qhov tseeb.
Ua tsaug rau kev nyeem ntawv, nyob xav paub thiab muaj lub limtiam zoo. 🙂
Ua tsaug uas koj tau nyob nrog peb. Koj puas nyiam peb cov ntawv? Xav pom cov ntsiab lus nthuav ntxiv? Txhawb nqa peb los ntawm kev tso ib qho kev txiav txim lossis qhia rau cov phooj ywg, 30% luv nqi rau cov neeg siv Habr ntawm qhov tshwj xeeb analogue ntawm nkag-theem servers, uas tau tsim los ntawm peb rau koj: (muaj nrog RAID1 thiab RAID10, mus txog 24 cores thiab mus txog 40GB DDR4).
Dell R730xd 2 zaug pheej yig dua? Tsuas yog nyob ntawm no hauv Netherlands! Dell R420 - 2x E5-2430 2.2Ghz 6C 128GB DDR3 2x960GB SSD 1Gbps 100TB - los ntawm $ 99! Nyeem txog
Tau qhov twg los: www.hab.com