{"id":39036,"date":"2019-10-31T22:27:30","date_gmt":"2019-10-31T19:27:30","guid":{"rendered":"https:\/\/prohoster.info\/blog\/dvumernyj-duet-sozdanie-borofen-grafenovyh-geterostruktur\/"},"modified":"2019-10-31T22:27:30","modified_gmt":"2019-10-31T19:27:30","slug":"dvumernyj-duet-sozdanie-borofen-grafenovyh-geterostruktur","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/news\/dvumernyj-duet-sozdanie-borofen-grafenovyh-geterostruktur","title":{"rendered":"Dvojdimenzion\u00e1lny duet: vytv\u00e1ranie borof\u00e9n-graf\u00e9nov\u00fdch hetero\u0161trukt\u00far","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"Dvojdimenzion\u00e1lny
\n
\n\u201eMut\u00e1cia je k\u013e\u00fa\u010dom k vyrie\u0161eniu tajomstva evol\u00facie. Cesta v\u00fdvoja od najjednoduch\u0161ieho organizmu po dominantn\u00fd biologick\u00fd druh trv\u00e1 tis\u00edce rokov. Ale ka\u017ed\u00fdch stovky tis\u00edc rokov sa v evol\u00facii odohr\u00e1va prudk\u00fd skok vpred\u201c (Charles Xavier, X-Men, 2000). Ak sa zbav\u00edme v\u0161etk\u00fdch vedecko-fantastick\u00fdch prvkov pr\u00edtomn\u00fdch v komiksoch a filmoch, slov\u00e1 profesora X s\u00fa celkom pravdiv\u00e9. V\u00fdvoj \u010dohoko\u013evek prebieha rovnomerne v\u00e4\u010d\u0161inu \u010dasu, ale niekedy sa objavia skoky, ktor\u00e9 maj\u00fa obrovsk\u00fd vplyv na cel\u00fd proces. To plat\u00ed nielen pre evol\u00faciu druhov, ale aj pre evol\u00faciu technol\u00f3gi\u00ed, ktor\u00fdch hlavn\u00fdm motorom s\u00fa \u013eudia, ich v\u00fdskum a vyn\u00e1lezy. Dnes sa s vami zozn\u00e1mime s v\u00fdskumom, ktor\u00fd pod\u013ea jeho autorov predstavuje skuto\u010dn\u00fd evolu\u010dn\u00fd skok v nanotechnol\u00f3gi\u00e1ch. Ako sa vedcom z Northwestern University (USA) podarilo vytvori\u0165 nov\u00fa dvojrozmern\u00fa heterostrukt\u00faru, pre\u010do boli ako z\u00e1klad zvolen\u00e9 graf\u00e9n a borof\u00e9n, a ak\u00fdmi vlastnos\u0165ami m\u00f4\u017ee tak\u00fdto syst\u00e9m disponova\u0165? O tom n\u00e1m povie spr\u00e1va v\u00fdskumnej skupiny. Ideme na to.<\/a><\/noindex><\/p>\n

Z\u00e1klad v\u00fdskumu<\/h3>\n

\nTerm\u00edn \u201egraf\u00e9n\u201c sme u\u017e po\u010duli mnohokr\u00e1t - je to dvojrozmern\u00e1 modifik\u00e1cia uhl\u00edka, pozost\u00e1vaj\u00faca z vrstvy at\u00f3mov uhl\u00edka hrubej 1 at\u00f3m. No \u201eborof\u00e9n\u201c sa vyskytuje ve\u013emi zriedka. Tento term\u00edn ozna\u010duje dvojrozmern\u00fd kry\u0161t\u00e1l, ktor\u00fd pozost\u00e1va v\u00fdlu\u010dne z at\u00f3mov b\u00f3ru (B). Mo\u017enos\u0165 existencie borof\u00e9nu bola prv\u00fdkr\u00e1t predpovedan\u00e1 u\u017e v polovici 90. rokov, ale prakticky sa t\u00fato \u0161trukt\u00faru podarilo z\u00edska\u0165 a\u017e v roku 2015. <\/p>\n

Atomov\u00e1 \u0161trukt\u00fara borof\u00e9nu pozost\u00e1va z trojuholn\u00edkov\u00fdch a hexagon\u00e1lnych prvkov a je v\u00fdsledkom interakcie medzi dvojcentrov\u00fdmi a mnohocentrov\u00fdmi vn\u00fatropl\u00e1nkov\u00fdmi v\u00e4zbami, \u010do je ve\u013emi charakteristick\u00e9 pre prvky s deficitom elektr\u00f3nov, medzi ktor\u00e9 patr\u00ed aj b\u00f3rok.<\/p>\n

*<\/b>Pod dvojcentrov\u00fdmi a mnohocentrov\u00fdmi v\u00e4zbami sa rozumej\u00fa chemick\u00e9 v\u00e4zby - interakcie at\u00f3mov, ktor\u00e9 charakterizuj\u00fa stabilitu molekuly alebo kry\u0161t\u00e1lu ako jedinej \u0161trukt\u00fary. Napr\u00edklad, dvojcentrov\u00e1 dvojelektr\u00f3nov\u00e1 v\u00e4zba vznik\u00e1, ke\u010f 2 at\u00f3my delia medzi sebou 2 elektr\u00f3ny, a dvojcentrov\u00e1 trojelektr\u00f3nov\u00e1 - 2 at\u00f3my a 3 elektr\u00f3ny at\u010f.<\/p><\/blockquote>\n

Z fyzick\u00e9ho h\u013eadiska m\u00f4\u017ee by\u0165 borofen odolnej\u0161\u00ed a flexibilnej\u0161\u00ed v porovnan\u00ed s graf\u00e9nom. Taktie\u017e sa predpoklad\u00e1, \u017ee borofenov\u00e9 \u0161trukt\u00fary m\u00f4\u017eu by\u0165 efekt\u00edvnym doplnkom pre bat\u00e9rie, preto\u017ee borofen m\u00e1 vysok\u00fa \u0161pecifick\u00fa kapacitu a jedine\u010dn\u00e9 vlastnosti elektronickej vodivosti a prenosu i\u00f3nov. V s\u00fa\u010dasnosti ide v\u0161ak len o te\u00f3riu.<\/p>\n

Ako trojvalentn\u00fd prvok*<\/i>, b\u00f3rov m\u00e1 najmenej 10 allotropov*<\/i>. V dvojdimenzion\u00e1lnej forme sa podobn\u00fd polymorfizmus*<\/i> taktie\u017e pozoruje. <\/p>\n

Trojvalentn\u00fd prvok*<\/b> je schopn\u00fd vytv\u00e1ra\u0165 tri kovalentn\u00e9 v\u00e4zby, ktor\u00fdch valentnos\u0165 je rovn\u00e1 trom. <\/p><\/blockquote>\n

Allotropia*<\/b> je situ\u00e1cia, ke\u010f m\u00f4\u017ee by\u0165 jeden chemick\u00fd prvok reprezentovan\u00fd vo forme dvoch alebo viacer\u00fdch jednoduch\u00fdch l\u00e1tok. Ako pr\u00edklad, uhl\u00edk \u2014 diamant, graf\u00e9n, grafit, uhl\u00edkov\u00e9 nanotrubice a pod.<\/p><\/blockquote>\n

Polymorfizmus*<\/b> je schopnos\u0165 l\u00e1tky existova\u0165 v r\u00f4znych kry\u0161talick\u00fdch \u0161trukt\u00farach (polymorfn\u00fdch modifik\u00e1ci\u00e1ch). V pr\u00edpade jednoduch\u00fdch l\u00e1tok je tento term\u00edn synonymom pre allotropiu. <\/p><\/blockquote>\n

S oh\u013eadom na tak \u0161irok\u00fd polymorfizmus vznik\u00e1 predpoklad, \u017ee borofen m\u00f4\u017ee by\u0165 vynikaj\u00facim kandid\u00e1tom na vytvorenie nov\u00fdch dvojdimenzion\u00e1lnych hetero\u0161trukt\u00far, preto\u017ee r\u00f4zne konfigur\u00e1cie v\u00e4zieb b\u00f3ru by mali oslabi\u0165 po\u017eiadavky na zladenie kry\u0161t\u00e1lovej mrie\u017eky. Bohu\u017eia\u013e, tento probl\u00e9m sa predt\u00fdm sk\u00famal v\u00fdlu\u010dne na teoretickej \u00farovni z d\u00f4vodu \u0165a\u017ekost\u00ed v synt\u00e9ze.<\/p>\n

Pre be\u017en\u00e9 2D materi\u00e1ly z\u00edskan\u00e9 z objemov\u00fdch vrstven\u00fdch kry\u0161t\u00e1lov m\u00f4\u017eu by\u0165 vertik\u00e1lne hetero\u0161trukt\u00fary realizovan\u00e9 pomocou mechanick\u00e9ho ukladania. Na druhej strane, dvojdimenzion\u00e1lne later\u00e1lne hetero\u0161trukt\u00fary s\u00fa zalo\u017een\u00e9 na vzostupnej synt\u00e9ze. At\u00f3movo presn\u00e9 later\u00e1lne hetero\u0161trukt\u00fary maj\u00fa ve\u013ek\u00fd potenci\u00e1l pri rie\u0161en\u00ed probl\u00e9mov s kontrolou funk\u010dn\u00fdch schopnost\u00ed heteroprehodu, av\u0161ak kv\u00f4li kovalentn\u00e9mu spojeniu nedokonal\u00e9 zladenie mrie\u017eky zvy\u010dajne vedie k \u0161irok\u00fdm a neusporiadan\u00fdm rozhraniam. Preto potenci\u00e1l existuje, ale s\u00fa tu aj probl\u00e9my s jeho realiz\u00e1ciou.<\/p>\n

V tomto diele sa v\u00fdskumn\u00edkom podarilo integrova\u0165 borofen a graf\u00e9n do jednej dvojrozmernej heterostrukt\u00fary. Napriek nes\u00fahlasu krystalografick\u00fdch mrie\u017eok a symetrie medzi borof\u00e9nom a graf\u00e9nom, sekven\u010dn\u00e9 usadzovanie uhl\u00edka a b\u00f3ru na substr\u00e1t z Ag(111) vo vysokom v\u00e1kuu (HV) vedie k takmer at\u00f3movo presn\u00fdm later\u00e1lnym heterointerface s predpovedan\u00fdmi mrie\u017ekov\u00fdmi zarovnan\u00edm, ako aj k vertik\u00e1lnym heterointerface. <\/p>\n

Pr\u00edprava na v\u00fdskum<\/h3>\n

\nPred v\u00fdskumom heterostrukt\u00fary ju bolo potrebn\u00e9 vyrobi\u0165. R\u0430\u0441\u0442 \u0433\u0440\u0430\u0444\u00e9nu a borof\u00e9nu prebieha v komore ultravysok\u00e9ho v\u00e1kuov\u00e9ho tlaku 1x10-10 milibar.<\/p>\n

Monokry\u0161t\u00e1lov\u00fd substr\u00e1t Ag(111) bol \u010disten\u00fd opakovan\u00fdmi cyklami rozpra\u0161ovania Ar+(1 x 10-5 milibar, energia 800 eV, 30 min\u00fat) a tepeln\u00fdm \u017e\u00edhan\u00edm (550 \u00b0C, 45 min\u00fat) a\u017e do z\u00edskania at\u00f3movo \u010dist\u00e9ho a ploch\u00e9ho povrchu Ag(111).<\/p>\n

Rast graf\u00e9nu sa uskuto\u010d\u0148oval prostredn\u00edctvom elektronov\u00e9ho l\u00fa\u010dov\u00e9ho odparovania \u010dist\u00e9ho (99,997%) grafitov\u00e9ho ty\u010de s priemerom 2,0 mm na zahriaty substr\u00e1t Ag (111) pri teplote 750 \u00b0C, s pr\u00fadov\u00fdm nap\u00e4t\u00edm ~ 1,6 A a ur\u00fdch\u013euj\u00facim nap\u00e4t\u00edm ~ 2 kV, \u010do d\u00e1va emisn\u00fd pr\u00fad ~ 70 mA a prietok uhl\u00edka ~ 40 nA. Tlak v komore bol 1 x 10-9 milibar.<\/p>\n

Rast borof\u00e9nu sa uskuto\u010d\u0148oval prostredn\u00edctvom elektronov\u00e9ho l\u00fa\u010dov\u00e9ho odparovania \u010dist\u00e9ho (99,9999%) b\u00f3rov\u00e9ho ty\u010de na zahriaty submonovrstvov\u00fd graf\u00e9n na Ag (111) s teplotou 400-500 \u00b0C. Pr\u00fadov\u00fd tok bol ~ 1,5 A a ur\u00fdch\u013euj\u00face nap\u00e4tie 1,75 kV, \u010do d\u00e1va emisn\u00fd pr\u00fad ~ 34 mA a prietok b\u00f3ru ~ 10 nA. Tlak v komore po\u010das rastu borof\u00e9nu bol pribli\u017ene 2 x 10-10 milibar.<\/p>\n

V\u00fdsledky \u0161t\u00fadie<\/h3>\n

\n\"Dvojdimenzion\u00e1lny
\nObr\u00e1zok \u010d. 1<\/i><\/p>\n

Na obr\u00e1zku 1A<\/b> je zobrazen\u00fd STM*<\/i> snimok vypestovan\u00e9ho graf\u00e9nu, kde sa graf\u00e9nov\u00e9 dom\u00e9ny najlep\u0161ie vizualizuj\u00fa pomocou mapy dI<\/i>\/dV<\/i> (1B<\/b>), kde I<\/i> a V<\/i> \u2014 tunelov\u00fd pr\u00fad a posun vzorky, a d<\/i> \u2014 hustota. <\/p>\n

STM*<\/b> \u2014 skenovac\u00ed tunelov\u00fd mikroskop.<\/p><\/blockquote>\n

dI<\/i>\/dV<\/i> mapy vzorky umo\u017enili vidie\u0165 vy\u0161\u0161iu lok\u00e1lnu hustotu stavov graf\u00e9nu v porovnan\u00ed so substr\u00e1tom Ag (111). V s\u00falade s predch\u00e1dzaj\u00facimi \u0161t\u00fadiami, povrchov\u00fd stav Ag (111) m\u00e1 schodovit\u00fa charakteristiku, posunut\u00fa smerom k pozit\u00edvnym energetick\u00fdm hodnot\u00e1m na dI<\/i>\/dV<\/i> spektru graf\u00e9nu (1C<\/b>), \u010do vysvet\u013euje vy\u0161\u0161iu lok\u00e1lnu hustotu stavov graf\u00e9nu na 1B<\/b> pri 0,3 eV.<\/p>\n

Na obr\u00e1zku 1D<\/b> m\u00f4\u017eeme vidie\u0165 \u0161trukt\u00faru jedno\u010dl\u00e1nkov\u00e9ho graf\u00e9nu, kde je jasne vidite\u013en\u00e1 mrie\u017eka a moir\u00e9ov\u00e1 nad\u0161trukt\u00fara*<\/i>.<\/p>\n

Superstruct\u00fara* <\/b> \u2014 vlastnos\u0165 \u0161trukt\u00fary kry\u0161talickej zl\u00fa\u010deniny, ktor\u00e1 sa opakuje s ur\u010dit\u00fdm intervalom a vytv\u00e1ra tak nov\u00fa \u0161trukt\u00faru s in\u00fdm peri\u00f3dov\u00fdm striedan\u00edm. <\/p>\n

Moar*<\/b> \u2014 prekrytie dvoch periodick\u00fdch mrie\u017ekov\u00fdch vzorov navz\u00e1jom.<\/p><\/blockquote>\n

Pri ni\u017e\u0161\u00edch teplot\u00e1ch rast vedie k tvorbe dendritick\u00fdch a defektn\u00fdch graf\u00e9nov\u00fdch dom\u00e9n. V d\u00f4sledku slab\u00fdch interakci\u00ed medzi graf\u00e9nom a podlo\u017en\u00fdm substr\u00e1tom nie je rota\u010dn\u00e9 zarovnanie graf\u00e9nu vo vz\u0165ahu k podlo\u017en\u00e9mu Ag (111) unik\u00e1tne.<\/p>\n

Po nanesen\u00ed b\u00f3ru skenovacia tunelov\u00e1 mikroskopia (1E<\/b>) uk\u00e1zala pr\u00edtomnos\u0165 zl\u00fa\u010denia b\u00f3rofenov\u00fdch a graf\u00e9nov\u00fdch dom\u00e9n. Na sn\u00edmke s\u00fa tie\u017e vidite\u013en\u00e9 oblasti vn\u00fatri graf\u00e9nu, ktor\u00e9 boli nesk\u00f4r definovan\u00e9 ako interkalovan\u00fd b\u00f3rofenom graf\u00e9n (ozna\u010den\u00fd na sn\u00edmke Gr\/B<\/b>). V tejto oblasti s\u00fa tie\u017e dobre vidite\u013en\u00e9 line\u00e1rne prvky, orientovan\u00e9 v troch smeroch a rozdelen\u00e9 pod uhlom 120 \u00b0 (\u017elt\u00e9 \u0161\u00edpky).<\/p>\n

\"Dvojdimenzion\u00e1lny
\nObr\u00e1zok \u010d. 2<\/i><\/p>\n

Sn\u00edmka na 2A<\/b>, rovnako ako 1E<\/b>, potvrdzuj\u00fa vznik lokalizovan\u00fdch tmav\u00fdch prehlbn\u00ed (depresi\u00ed) v graf\u00e9ne po nanesen\u00ed b\u00f3ru.<\/p>\n

Aby sme lep\u0161ie presk\u00famali tieto form\u00e1cie a zistili ich p\u00f4vod, bola uroben\u00e1 \u010fal\u0161ia sn\u00edmka tej istej oblasti, ale s pou\u017eit\u00edm m\u00e1p |dlnI<\/i>\/dz| (2\u0412), \u0433\u0434\u0435 I<\/i> \u2014 tunelov\u00fd pr\u00fad, d<\/i> \u2014 hustota, a z<\/i> \u2014 rozdelenie sondu-vzorka (medzera medzi ihlou mikroskopu a vzorkou). Aplik\u00e1cia tejto met\u00f3dy umo\u017e\u0148uje z\u00edska\u0165 obr\u00e1zky s vy\u0161\u0161\u00edm priestorov\u00fdm rozl\u00ed\u0161en\u00edm. Na tento \u00fa\u010del je tie\u017e mo\u017en\u00e9 pou\u017ei\u0165 CO alebo H2 na ihle mikroskopu. <\/p>\n

Obr\u00e1zok 2C<\/b> je sn\u00edmkou z\u00edskanou pomocou STM, ktorej ihla bola pokryt\u00e1 CO. Porovnanie sn\u00edmok A<\/b>, V<\/b> a S<\/b> ukazuje, \u017ee v\u0161etky atom\u00e1rne prvky s\u00fa ur\u010den\u00e9 ako tri susedn\u00e9 jasn\u00e9 \u0161es\u0165uholn\u00edky, orientovan\u00e9 v dvoch neekvivalentn\u00fdch smeroch (\u010derven\u00e9 a \u017elt\u00e9 trojuholn\u00edky na sn\u00edmkach). <\/p>\n

Zv\u00e4\u010d\u0161en\u00e9 sn\u00edmky tejto oblasti (2D<\/b>) potvrdzuj\u00fa, \u017ee tieto prvky s\u00fa v s\u00falade s leguj\u00facimi pr\u00edsadami b\u00f3ru, ktor\u00e9 zaberaj\u00fa dve podmrie\u017eky graf\u00e9nu, \u010do nazna\u010duj\u00fa aj prekryt\u00e9 \u0161trukt\u00fary.<\/p>\n

Pokrytie CO na ihle mikroskopu umo\u017enilo odhali\u0165 geometrick\u00fa \u0161trukt\u00faru listu b\u00f3rofeny (2E<\/b>), \u010do by nebolo mo\u017en\u00e9, keby bola ihla \u0161tandardn\u00e1 (kovov\u00e1) bez pokrytia CO.<\/p>\n

\"Dvojdimenzion\u00e1lny
\nObr\u00e1zok \u010d. 3<\/i><\/p>\n

Tvorba later\u00e1lnych heterointerface medzi borofenom a graf\u00e9nom (3A<\/b>) by mala nasta\u0165 v pr\u00edpade, ke\u010f borofen rastie ved\u013ea dom\u00e9n graf\u00e9nu, v ktorom u\u017e je bor. <\/p>\n

Vedci pripom\u00ednaj\u00fa, \u017ee later\u00e1lne heterointerface na b\u00e1ze graf\u00e9n-hBN (graf\u00e9n + nitrid b\u00f3ru) maj\u00fa zhodu mrie\u017eok, zatia\u013e \u010do heteroprejazdy na b\u00e1ze dichalkogenidov prechodn\u00fdch kovov maj\u00fa zhodu symetri\u00ed. V pr\u00edpade graf\u00e9nu\/borofenu je situ\u00e1cia trochu in\u00e1 \u2014 maj\u00fa minim\u00e1lnu \u0161truktur\u00e1lnu podobnos\u0165 z h\u013eadiska kon\u0161tant mrie\u017eky alebo kry\u0161talickej symetrie. Napriek tomu, later\u00e1lny heterointerface graf\u00e9n\/borofen vykazuje takmer ide\u00e1lnu atom\u00e1rnu zhodu, pri\u010dom smer borov\u00fdch radov (B-row) je zarovnan\u00fd so z\u00fabkov\u00fdmi (ZZ) smermi graf\u00e9nu (3A<\/b>). Na 3B<\/b> je zobrazen\u00fd zv\u00e4\u010d\u0161en\u00fd sn\u00edmok oblasti ZZ heterointerface (modr\u00e9 \u010diary ozna\u010duj\u00fa medzif\u00e1zov\u00e9 prvky, ktor\u00e9 zodpovedaj\u00fa bor-uhl\u00edkov\u00fdm kovalentn\u00fdm v\u00e4zb\u00e1m).<\/p>\n

Ke\u010f\u017ee rast borofenu prebieha pri ni\u017e\u0161ej teplote v porovnan\u00ed s graf\u00e9nom, okraje graf\u00e9novej dom\u00e9ny pravdepodobne nebud\u00fa ma\u0165 vysok\u00fa mobilitu pri tvorbe heterointerface s borofenom. Preto takmer atom\u00e1rne presn\u00fd heterointerface pravdepodobne vznik\u00e1 v d\u00f4sledku r\u00f4znych konfigur\u00e1ci\u00ed a charakterist\u00edk viaccentrov\u00fdch v\u00e4zieb b\u00f3ru. Spektr\u00e1 skenuj\u00facej tunelovej spektroskopie (3C<\/b>) a diferenci\u00e1lnej tunelovej vodivosti (3D<\/b>) ukazuj\u00fa, \u017ee elektronov\u00fd prechod z graf\u00e9nu na borofen prebieha na vzdialenosti ~ 5 \u00c5 bez vidite\u013en\u00fdch stavov interface.<\/p>\n

Na obr\u00e1zku 3E<\/b> s\u00fa zobrazen\u00e9 tri spektr\u00e1 skenuj\u00facej tunelovej spektroskopie, vykonan\u00e9 pozd\u013a\u017e troch bodkovan\u00fdch \u010diar na 3D, ktor\u00e9 potvrdzuj\u00fa, \u017ee tento kr\u00e1tky elektronov\u00fd prechod je necitliv\u00fd na miestne medzif\u00e1zov\u00e9 \u0161trukt\u00fary a porovnate\u013en\u00fd s podobn\u00fdm na rozhran\u00ed borofen-striebro. <\/p>\n

\"Dvojdimenzion\u00e1lny
\nObr\u00e1zok \u010d. 4<\/i><\/p>\n

Graf\u00e9nov\u00e1 interkal\u00e1cia*<\/i> bola u\u017e tie\u017e \u0161iroko sk\u00faman\u00e1, av\u0161ak konverzia interkalantov na skuto\u010dn\u00e9 2D-listy je relat\u00edvne zriedkav\u00fdm javom.<\/p>\n

Interkal\u00e1cia*<\/b> je vratn\u00e9 zaradenie molekuly alebo skupiny molek\u00fal medzi in\u00e9 molekuly alebo skupiny molek\u00fal.<\/p><\/blockquote>\n

Mal\u00fd atomov\u00fd polomer b\u00f3ru a slab\u00e9 interakcie medzi graf\u00e9nom a Ag (111) nazna\u010duj\u00fa mo\u017enos\u0165 interkal\u00e1cie graf\u00e9nu s b\u00f3rom. Na obr\u00e1zku 4A<\/b> s\u00fa uveden\u00e9 d\u00f4kazy o interkal\u00e1cii b\u00f3ru, ako aj o vytv\u00e1ran\u00ed vertik\u00e1lnych borofen-graf\u00e9nov\u00fdch heterostrukt\u00far, najm\u00e4 trojholn\u00edkov\u00fdch dom\u00e9n obklopen\u00fdch graf\u00e9nom. Mrie\u017eka, pozorovan\u00e1 na tejto trojholn\u00edkovej dom\u00e9ne, potvrdzuje pr\u00edtomnos\u0165 graf\u00e9nu. Av\u0161ak tento graf\u00e9n vykazuje ni\u017e\u0161iu lok\u00e1lnu hustotu stavov pri -50 meV v porovnan\u00ed s okoln\u00fdm graf\u00e9nom (4B<\/b>). V porovnan\u00ed s graf\u00e9nom priamo na Ag (111) absencia znakov vysokej lok\u00e1lnej hustoty stavov v spektre dI<\/i>\/dV<\/i> (4C<\/b>, modr\u00e1 krivka), zodpovedaj\u00faca povrchov\u00e9mu stavu Ag (111), je prv\u00fdm d\u00f4kazom interkal\u00e1cie b\u00f3ru.<\/p>\n

Rovnako ako bolo o\u010dak\u00e1van\u00e9 pre parcielnu interkal\u00e1ciu, graf\u00e9nov\u00e1 mrie\u017eka zost\u00e1va kontinu\u00e1lna po celom later\u00e1lnom rozhran\u00ed medzi graf\u00e9nom a trojuholn\u00edkovou oblas\u0165ou (4D<\/b> \u2014 zodpoved\u00e1 obdl\u017en\u00edkovej oblasti na 4A<\/b>, ozna\u010denej \u010dervenou bodkovanou \u010diarou). Sn\u00edmok pomocou AFM potvrdil pr\u00edtomnos\u0165 substitu\u010dn\u00fdch ne\u010dist\u00f4t b\u00f3ru (4E<\/b> \u2014 zodpoved\u00e1 obdl\u017en\u00edkovej oblasti na 4A<\/b>, ozna\u010denej \u017eltou bodkovanou \u010diarou).<\/p>\n

Po\u010das anal\u00fdzy sa pou\u017e\u00edvali aj ihly mikroskopu bez ak\u00e9hoko\u013evek povlaku. V takom pr\u00edpade sa v interkalovan\u00fdch graf\u00e9nov\u00fdch dom\u00e9nach objavili znaky jednorozmern\u00fdch line\u00e1rnych prvkov s periodicitou 5 \u00c5 (4F<\/b> a 4G<\/b>). Tieto jednorozmern\u00e9 \u0161trukt\u00fary pripom\u00ednaj\u00fa rady b\u00f3ru v modeli borof\u00e9nu. Okrem s\u00faboru bodov, ktor\u00e9 zodpovedaj\u00fa graf\u00e9nu, Fourierova transform\u00e1cia sn\u00edmku na 4G<\/b> zobrazuje p\u00e1r ortogon\u00e1lnych bodov, ktor\u00e9 zodpovedaj\u00fa obd\u013a\u017enikovej mrie\u017eke 3 \u00c5 x 5 \u00c5 (4H<\/b>), \u010do v\u00fdborne s\u00fahlas\u00ed s modelom borof\u00e9nu. Navy\u0161e, pozorovan\u00e1 trojit\u00e1 orient\u00e1cia mrie\u017eky line\u00e1rnych prvkov (1E<\/b>) dobre s\u00fahlas\u00ed s tou istou prevl\u00e1daj\u00facou \u0161trukt\u00farou, ktor\u00e1 sa pozoruje pre listy borof\u00e9nu.<\/p>\n

V\u0161etky tieto pozorovania presved\u010divo sved\u010dia o interkal\u00e1cii graf\u00e9nu borof\u00e9nom v bl\u00edzkosti okrajov Ag, \u010do vedie k tvorbe vertik\u00e1lnych heterostrukt\u00far borof\u00e9n-graf\u00e9n, ktor\u00e9 m\u00f4\u017eu by\u0165 preva\u017ene realizovan\u00e9 zv\u00fd\u0161en\u00edm po\u010diato\u010dn\u00e9ho pokrytia graf\u00e9nom.<\/p>\n

4I<\/b> je sch\u00e9matick\u00e9 zn\u00e1zornenie vertik\u00e1lnej heterostrukt\u00fary na 4H<\/b>, kde je smer radu b\u00f3ru (ru\u017eov\u00e1 \u0161\u00edpka) tesne vyrovnan\u00fd so zubat\u00fdm smerom graf\u00e9nu (\u010dierna \u0161\u00edpka), \u010d\u00edm sa vytv\u00e1ra rotuj\u00faca a rozmerov\u00e1 vertik\u00e1lna heterostrukt\u00fara.<\/p>\n

Pre podrobnej\u0161ie obozn\u00e1menie s nuansami v\u00fdskumu odpor\u00fa\u010dam pozrie\u0165 sa do spr\u00e1vy vedcov<\/a><\/noindex> a \u010fal\u0161ie materi\u00e1ly<\/a><\/noindex> k nej.<\/p>\n

Epilog<\/h3>\n

\nT\u00e1to \u0161t\u00fadia uk\u00e1zala, \u017ee borofen je plne schopn\u00fd tvori\u0165 later\u00e1lne a vertik\u00e1lne heterostrukt\u00fary s graf\u00e9nom. Podobn\u00e9 syst\u00e9my m\u00f4\u017eu by\u0165 vyu\u017eit\u00e9 pri v\u00fdvoji nov\u00fdch typov dvojrozmern\u00fdch komponentov v nanotechnol\u00f3gi\u00e1ch, flexibilnej a nosite\u013enej elektronike, ako aj v nov\u00fdch typoch polovodi\u010dov.<\/p>\n

Samotn\u00ed vedci sa domnievaj\u00fa, \u017ee ich v\u00fdvoj m\u00f4\u017ee by\u0165 siln\u00fdm impulzom pre technol\u00f3gie spojen\u00e9 s elektronikou. Av\u0161ak poveda\u0165 s istotou, \u017ee ich slov\u00e1 sa stan\u00fa prorock\u00fdmi, zatia\u013e nie je mo\u017en\u00e9. V tejto chv\u00edli je e\u0161te ve\u013ea potrebn\u00e9 presk\u00fama\u0165, pochopi\u0165 a vyn\u00e1js\u0165, aby sa tie vedecko-fantastick\u00e9 n\u00e1pady, ktor\u00e9 zapl\u0148uj\u00fa mysle vedcov, stali plnohodnotnou realitou.<\/p>\n

\u010eakujem za pozornos\u0165, zost\u00e1vajte zvedav\u00ed a \u017eel\u00e1m v\u0161etk\u00fdm dobr\u00fd pracovn\u00fd t\u00fd\u017ede\u0148, chalani. \ud83d\ude42<\/p>\n

\u010eakujeme, \u017ee ost\u00e1vate s nami. P\u00e1\u010dia sa v\u00e1m na\u0161e \u010dl\u00e1nky? Chcete vidie\u0165 viac zauj\u00edmav\u00fdch materi\u00e1lov? Podporte n\u00e1s, vytvoren\u00edm objedn\u00e1vky alebo odpor\u00fa\u010dan\u00edm zn\u00e1mym, 30% z\u013eava pre pou\u017e\u00edvate\u013eov Chabra na unik\u00e1tny ekvivalent entry-level serverov, ktor\u00fd sme pre v\u00e1s vytvorili:<\/b> V\u0161etky pravdy o VPS (KVM) E5-2650 v4 (6 jadier) 10GB DDR4 240GB SSD 1Gbps od 20 dol\u00e1rov alebo ako spr\u00e1vne rozdeli\u0165 server?<\/a><\/noindex> (k dispoz\u00edcii varianty s RAID1 a RAID10, a\u017e 24 jadier a a\u017e 40GB DDR4).<\/p>\n

Dell R730xd za polovicu?<\/b> Len u n\u00e1s 2 x Intel TetraDeca-Core Xeon 2x E5-2697v3 2.6GHz 14C 64GB DDR4 4x960GB SSD 1Gbps 100 TB od 199 dol\u00e1rov<\/a><\/noindex> v Holandsku! Dell R420 \u2014 2x E5-2430 2.2Ghz 6C 128GB DDR3 2x960GB SSD 1Gbps 100TB \u2014 od 99 dol\u00e1rov!<\/b><\/b> Pre\u010d\u00edtajte si o tom Ako vybudova\u0165 infra\u0161trukt\u00faru korpor\u00e1tneho typu s pou\u017eit\u00edm serverov Dell R730xd E5-2650 v4 s cenou 9000 eur za zlomok ceny?<\/a><\/noindex>
\n
Zdroj: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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