“Kusintha kwa masinthidwe ndiko mfungulo yovumbula chinsinsi cha chisinthiko. Njira yachitukuko kuchokera ku chamoyo chosavuta kupita ku mitundu yayikulu yazamoyo imatha zaka masauzande ambiri. Koma zaka 2000 zilizonse pamakhala kulumpha kwakukulu kwachisinthiko" (Charles Xavier, X-Men, XNUMX). Ngati titaya zinthu zonse zopeka za sayansi zomwe zimapezeka muzithunzithunzi ndi mafilimu, ndiye kuti mawu a Pulofesa X ndi oona. Kukula kwa chinthu kumachitika mofanana nthawi zambiri, koma nthawi zina pali kulumpha komwe kumakhudza kwambiri ndondomeko yonseyi. Izi sizikugwiranso ntchito pa kusinthika kwa zamoyo, komanso kusinthika kwa teknoloji, dalaivala wamkulu yemwe ali anthu, kafukufuku wawo ndi zatsopano. Lero tidziwana ndi kafukufuku yemwe, malinga ndi olemba ake, ndikusintha kwenikweni kwa nanotechnology. Kodi asayansi aku Northwestern University (USA) adakwanitsa bwanji kupanga mawonekedwe atsopano amitundu iwiri, chifukwa chiyani graphene ndi borophene zidasankhidwa kukhala maziko, ndipo ndi zinthu ziti zomwe dongosolo loterolo lingakhale nalo? Lipoti la gulu lofufuza litiuza za izi. Pitani.
Maziko ofufuza
Tamva mawu oti "graphene" nthawi zambiri, ndikusintha kwamitundu iwiri ya kaboni, yomwe imakhala ndi gawo la maatomu a carbon 1 atomu yokhuthala. Koma "borofen" ndi osowa kwambiri. Mawuwa amatanthauza kristalo wa mbali ziwiri wokhala ndi maatomu a boroni (B). Kuthekera kwa kukhalapo kwa borophene kudanenedweratu m'ma 90s, koma pochita izi zidangopezedwa ndi 2015.
Mapangidwe a atomiki a borophene amakhala ndi zinthu zitatu ndi zitatu ndipo ndi zotsatira za mgwirizano pakati pa ma bondi apakati ndi apakati pa ndege, omwe ndi ofanana kwambiri ndi zinthu zopanda ma elekitironi, zomwe zimaphatikizapo boron.
*Ndi maunyolo apakati ndi ma multicenter timatanthawuza mgwirizano wamankhwala - kuyanjana kwa maatomu omwe amawonetsa kukhazikika kwa molekyulu kapena kristalo ngati chinthu chimodzi. Mwachitsanzo, awiri pakati awiri ma elekitironi chomangira kumachitika pamene 2 maatomu kugawana 2 ma elekitironi, ndi awiri pakati atatu ma elekitironi chomangira kumachitika pamene 2 maatomu ndi 3 ma elekitironi, etc.
Kuchokera pakuwona kwakuthupi, borophene ikhoza kukhala yamphamvu komanso yosinthika kuposa graphene. Amakhulupiriranso kuti mapangidwe a borophene atha kukhala othandizira bwino mabatire, popeza borophene ili ndi mphamvu zapadera komanso mawonekedwe apadera amagetsi ndi katundu wa ion zoyendera. Komabe, pakali pano ichi ndi chiphunzitso chabe.
Kukhala trivalent element*, boron ili ndi osachepera 10 allotropes *. Mu mawonekedwe amitundu iwiri, ofanana polymorphism * imawonedwanso.
Trivalent element* wokhoza kupanga zomangira zitatu za covalent, valency yomwe ili itatu.
Allotropy* - pamene chinthu chimodzi cha mankhwala chikhoza kuperekedwa mu mawonekedwe a zinthu ziwiri kapena zingapo zosavuta. Mwachitsanzo, carbon - diamondi, graphene, graphite, mpweya nanotubes, etc.
Polymorphism * - kuthekera kwa chinthu kukhalapo mumitundu yosiyanasiyana ya kristalo (zosintha zapolymorphic). Pankhani ya zinthu zosavuta, mawuwa ndi ofanana ndi allotropy.
Poganizira za polymorphism yayikuluyi, akuti borophene ikhoza kukhala njira yabwino kwambiri yopangira ma heterostructures amitundu iwiri, popeza masinthidwe osiyanasiyana a boron amayenera kumasula zofunikira zofananira ndi latisi. Tsoka ilo, nkhaniyi idaphunziridwa kale pamlingo wongoyerekeza chifukwa cha zovuta pakuphatikiza.
Pazinthu wamba za 2D zopezedwa kuchokera ku makhiristo ambiri osanjikiza, ma heterostructures osunthika amatha kuzindikirika pogwiritsa ntchito makina ojambulira. Kumbali inayi, ma heterostructures awiri-dimensional lateral amachokera kumunsi-mmwamba kaphatikizidwe. Ma atomically lateral heterostructures ali ndi kuthekera kwakukulu pakuthana ndi zovuta zowongolera magwiridwe antchito a heterojunction, komabe, chifukwa cha kulumikizana kogwirizana, kufananiza kwa latisi kopanda ungwiro kumapangitsa kuti pakhale malo otalikirana komanso osokonekera. Choncho, pali kuthekera, koma palinso mavuto pakuzindikira.
Mu ntchitoyi, ochita kafukufuku adatha kuphatikiza borophene ndi graphene mu heterostructure imodzi yamitundu iwiri. Ngakhale kuti crystallographic lattice imasokonekera komanso yofananira pakati pa borophene ndi graphene, kuyika motsatizana kwa kaboni ndi boron pagawo la Ag (111) pansi pa vacuum yapamwamba kwambiri (UHV) kumapangitsa kuti ma atomu am'mbali am'mbali akhale olondola kwambiri okhala ndi mizere yoloseredwa ya lattice, komanso mopingasa. .
Kukonzekera phunziro
Asanaphunzire za heterostructure, idayenera kupangidwa. Kukula kwa graphene ndi borophene kunkachitika m'chipinda chapamwamba kwambiri cha vacuum chokhala ndi mphamvu ya 1x10-10 millibars.
Gawo limodzi la crystal Ag (111) lidatsukidwa ndi kubwerezabwereza kwa Ar + sputtering (1 x 10-5 millibar, 800 eV, mphindi 30) ndi kutentha kwa kutentha (550 ° C, mphindi 45) kuti apeze Ag yoyera ndi yosalala. 111) pamwamba..
Graphene idakulitsidwa ndi kutuluka kwa ma elekitironi pamtengo wa ndodo ya graphite yoyera (99,997%) yokhala ndi mainchesi 2.0 mm pagawo la Ag (750) lotenthedwa mpaka 111 °C pakutentha kwapano kwa ~ 1.6 A ndi mphamvu yothamanga ya ~ 2 kV , yomwe imapereka mpweya wa ~ 70 mA ndi carbon flux ~ 40 nA. Kupanikizika m'chipindacho kunali 1 x 10-9 millibars.
Borophene idakulitsidwa kudzera mu evaporation ya ma elekitironi ya boroni yoyera (99,9999%) pa submonolayer graphene pa Ag (400) yotenthedwa mpaka 500-111 °C. Mphamvu yamagetsi inali ~ 1.5 A ndipo mphamvu yothamanga inali 1.75 kV, yomwe imapereka mpweya wa ~ 34 mA ndi boron flux ~ 10 nA. Kupanikizika m'chipindamo panthawi ya kukula kwa borophene kunali pafupifupi 2 x 10-10 millibars.
Zotsatira za kafukufuku
Chithunzi #1
Pa chithunzi 1A wasonyeza STM* chithunzithunzi chakukula kwa graphene, komwe madera a graphene amawonetsedwa bwino pogwiritsa ntchito mapu dI/dV (1B), pati I и V ndi tunneling panopa ndi zitsanzo kusamuka, ndi d - kachulukidwe.
STM* - kusanthula maikulosikopu.
dI/dV mamapu achitsanzo atilola kuwona kuchulukirachulukira kwapamwamba kwa mayiko a graphene poyerekeza ndi gawo lapansi la Ag(111). Mogwirizana ndi maphunziro am'mbuyomu, mawonekedwe a Ag (111) ali ndi mawonekedwe, amasinthidwa kupita ku mphamvu zabwino dI/dV mtundu wa graphene (1С), chomwe chimafotokoza za kuchuluka kwapang'onopang'ono kwamayiko a graphene pa 1B ku 0.3v.
Pa chithunzi 1D tikhoza kuona kapangidwe ka single-wosanjikiza graphene, kumene zisa zisa zikuonekera bwino ndi moiré superstructure *.
Superstructure* - mawonekedwe a mawonekedwe a crystalline pawiri omwe amabwereza pakapita nthawi ndipo motero amapanga mawonekedwe atsopano ndi nthawi yosiyana.
Moire* - superposition of two periodic mesh mapatani pamwamba pa mzake.
Pa kutentha otsika, kukula kumabweretsa mapangidwe dendritic ndi zosalongosoka graphene madambwe. Chifukwa cha kusagwirizana kofooka pakati pa graphene ndi gawo lapansi lapansi, kusinthasintha kozungulira kwa graphene ponena za Ag (111) yomwe ili pansi pake si yapadera.
Pambuyo pakuyika kwa boron, kusanthula ma microscopy (Kufotokozera:) adawonetsa kukhalapo kwa zigawo za borophene ndi graphene. Zomwe zikuwonekera pachithunzichi ndi zigawo zamkati mwa graphene, zomwe pambuyo pake zidadziwika kuti graphene yolumikizidwa ndi borophene (yowonetsedwa pachithunzichi). Gr/B). Zinthu zokhala ndi mzere wolunjika mbali zitatu ndikulekanitsidwa ndi ngodya ya 120 ° zimawonekeranso bwino mderali (mivi yachikasu).
Chithunzi #2
Chithunzi pa 2Akomanso Kufotokozera:, kutsimikizira kuwoneka kwa mdima wakuda mu graphene pambuyo poyika boron.
Kuti muwone bwino mapangidwe awa ndikupeza komwe adachokera, chithunzi china chinajambulidwa cha malo omwewo, koma pogwiritsa ntchito mapu |dlnI/dz| (2b), ku I - Tunnel current, d ndi kachulukidwe, ndi z - kulekanitsa kwachitsanzo (mpata pakati pa singano ya microscope ndi chitsanzo). Kugwiritsiridwa ntchito kwa njirayi kumapangitsa kuti zitheke kupeza zithunzi zokhala ndi malo apamwamba. Mukhozanso kugwiritsa ntchito CO kapena H2 pa singano ya microscope pa izi.
chithunzi 2С ndi chithunzi chopezedwa pogwiritsa ntchito STM yomwe nsonga yake idakutidwa ndi CO. Kuyerekeza kwa zithunzi А, В и С ikuwonetsa kuti maelementi onse a atomiki amatanthauzidwa ngati ma hexagoni atatu owala oyandikana olunjika mbali ziwiri zosagwirizana (makona atatu ofiira ndi achikasu pazithunzi).
Zithunzi zazikuluzikulu za derali (2D) amatsimikizira kuti zinthuzi zikugwirizana ndi zonyansa za boron dopant, zomwe zimakhala ndi ma graphene sublattices awiri, monga momwe zimasonyezedwera ndi mapangidwe apamwamba.
Kuphimba kwa CO kwa singano ya microscope kunapangitsa kuti zitheke kuwulula mawonekedwe a geometric a pepala la borophene (Kufotokozera:), zomwe sizikanatheka ngati singanoyo inali yokhazikika (zitsulo) popanda zokutira za CO.
Chithunzi #3
Kupanga ma lateral heterointerfaces pakati pa borophene ndi graphene (3A) ziyenera kuchitika pamene borophene ikukula pafupi ndi madera a graphene omwe ali ndi boron kale.
Asayansi amakumbutsa kuti lateral heterointerfaces zochokera graphene-hBN (graphene + boron nitride) ndi lattice kusasinthasintha, ndi heterojunctions zochokera kusintha zitsulo dichalcogenides ndi symmetry kusasinthasintha. Pankhani ya graphene/borophene, zinthu ndizosiyana pang'ono - zimakhala ndi mawonekedwe ocheperako potengera ma lattice constants kapena crystal symmetry. Komabe, ngakhale izi, lateral graphene/borophene heterointerface amasonyeza pafupifupi wangwiro atomiki kusasinthasintha, ndi boron mzere (B-mzere) mayendedwe ogwirizana ndi zigzag (ZZ) malangizo a graphene (3A) Pa 3B chithunzi chokulirapo cha dera la ZZ la heterointerface chikuwonetsedwa (mizere yabuluu ikuwonetsa zinthu zolumikizana ndi boron-carbon covalent bond).
Popeza borophene amakula pa kutentha otsika poyerekeza graphene, m'mbali mwa ankalamulira graphene ndi chodziwikiratu kuti kuyenda mkulu popanga heterointerface ndi borophene. Chifukwa chake, ma heterointerface olondola kwambiri atomu mwina ndi chifukwa cha masinthidwe osiyanasiyana ndi mawonekedwe a ma boron ambiri. Kujambula tunneling spectroscopy spectra (3С) ndi machulukidwe osiyanasiyana (3D) kuwonetsa kuti kusintha kwamagetsi kuchokera ku graphene kupita ku borophene kumachitika pamtunda wa ~ 5 Å popanda mayiko owonekera.
Pa chithunzi Kufotokozera: Kuwonetsedwa ndi mawonekedwe atatu ojambulira makina ojambulidwa motsatizana ndi mizere itatu yodukaduka mu 3D, zomwe zimatsimikizira kuti kusintha kwakanthawi kwamagetsi kumeneku sikukhudzidwa ndi mawonekedwe am'deralo ndipo kungafanane ndi komwe kumalumikizana ndi borophene-silver.
Chithunzi #4
Graphene kulumikizana* adaphunziranso kale kwambiri, komabe kutembenuka kwa intercalants kukhala mapepala enieni a 2D ndikosowa.
Kulumikizana* - kuphatikiza kosinthika kwa molekyulu kapena gulu la mamolekyu pakati pa mamolekyu ena kapena magulu a mamolekyu.
Kagawo kakang'ono ka atomiki ka boroni ndi kulumikizana kofooka pakati pa graphene ndi Ag(111) zikuwonetsa kuthekera kolumikizana kwa graphene ndi boroni. Mu chithunzi 4A umboni umaperekedwa osati wa intercalation boron, komanso mapangidwe ofukula borophene-graphene heterostructures, makamaka triangular madera ozunguliridwa ndi graphene. Chisa cha uchi chomwe chimawonedwa pamagawo atatu awa chimatsimikizira kukhalapo kwa graphene. Komabe, graphene iyi ikuwonetsa kuchulukira kocheperako kwa mayiko ku -50 meV poyerekeza ndi graphene yozungulira (4B). Poyerekeza ndi graphene mwachindunji pa Ag(111), palibe umboni wa kachulukidwe mkulu wa mayiko mu sipekitiramu. dI/dV (4C, curve ya buluu), yofanana ndi Ag (111) pamwamba, ndi umboni woyamba wa kusakanikirana kwa boron.
Komanso, monga kuyembekezera kwa tsankho intercalation, ndi graphene lattice amakhala mosalekeza mu ofananira nawo mawonekedwe pakati graphene ndi chigawo triangular (4D - chikufanana ndi dera amakona anayi 4Amozungulira mzere wa madontho ofiira). Chithunzi chogwiritsa ntchito CO pa singano ya microscope chinatsimikiziranso kukhalapo kwa zonyansa zolowa m'malo mwa boron (4E - chikufanana ndi dera amakona anayi 4A, mozungulira mzere wa madontho achikasu).
Singano za microscope popanda zokutira zinagwiritsidwanso ntchito pakuwunika. Pachifukwa ichi, zizindikiro za mzere wamtundu umodzi wokhala ndi nthawi ya 5 Å zidawululidwa m'magawo osakanikirana a graphene (4F и 4G). Mapangidwe amtundu umodziwa amafanana ndi mizere ya boron mu chitsanzo cha borophene. Kuwonjezera pa mfundo zogwirizana ndi graphene, Fourier amasintha chithunzicho kukhala 4G akuwonetsa mfundo za orthogonal zofanana ndi 3 Å x 5 Å latisi yamakona anayi (4H pa), zomwe zimagwirizana kwambiri ndi chitsanzo cha borophene. Kuphatikiza apo, kuyang'ana katatu kwamitundu yosiyanasiyana (Kufotokozera:) imagwirizana bwino ndi mawonekedwe omwewo omwe amawonedwa pamapepala a borophene.
Zonsezi zikusonyeza mwamphamvu kusakanikirana kwa graphene ndi borophene pafupi ndi m'mphepete mwa Ag, zomwe zimapangitsa kuti mapangidwe apangidwe a borophene-graphene heterostructures, omwe angathe kuzindikiridwa mwachidwi powonjezera kufalitsa koyamba kwa graphene.
4I ndi chithunzi choyimira cha mawonekedwe oyima pa 4H, kumene mayendedwe a mzere wa boron (pinki muvi) amagwirizana kwambiri ndi njira ya zigzag ya graphene (muvi wakuda), motero amapanga mawonekedwe ozungulira ozungulira.
Kuti mudziwe zambiri za ma nuances a phunziroli, ndikupangira kuyang'ana и kwa iye.
Epilogue
Kafukufukuyu adawonetsa kuti borophene imatha kupanga ma heterostructures am'mbali komanso ofukula ndi graphene. Machitidwe oterewa angagwiritsidwe ntchito popanga mitundu yatsopano ya zinthu ziwiri-dimensional zomwe zimagwiritsidwa ntchito mu nanotechnology, flexible and wearable electronics, komanso mitundu yatsopano ya semiconductors.
Ofufuzawo amakhulupirira kuti chitukuko chawo chikhoza kukhala kulimbikitsana kwamphamvu kwaukadaulo wokhudzana ndi zamagetsi. Komabe, n’zovuta kunena motsimikiza kuti mawu awo adzakhala aulosi. Pakalipano, pali zambiri zoti zifufuzidwe, kumvetsetsedwa ndi kupangidwa kuti malingaliro a sayansi omwe amadzaza maganizo a asayansi akhale zenizeni zenizeni.
Zikomo powerenga, khalani ndi chidwi ndikukhala ndi sabata yabwino anyamata. 🙂
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Source: www.habr.com