Ua tsaug rau koj rau npe nrog Physics World Yog tias koj xav hloov koj cov ntsiab lus txhua lub sijhawm, thov mus saib kuv tus account
Graphite films tuaj yeem tiv thaiv cov khoom siv hluav taws xob los ntawm hluav taws xob hluav taws xob (EM) hluav taws xob, tab sis cov txheej txheem tam sim no rau kev tsim khoom siv sijhawm ob peb teev thiab yuav tsum tau ua qhov kub ntawm ib puag ncig 3000 ° C. Ib pab neeg tshawb fawb los ntawm Shenyang National Laboratory for Materials Science ntawm Tuam Tshoj Academy of Sciences tam sim no tau qhia lwm txoj hauv kev los ua cov yeeb yaj kiab zoo tshaj plaws hauv ob peb vib nas this los ntawm kev tua cov kab kub nickel ntawv ci hauv ethanol. Qhov kev loj hlob ntawm cov yeeb yaj kiab no yog ntau tshaj li ob qhov kev txiav txim siab ntau dua li cov txheej txheem uas twb muaj lawm, thiab cov yeeb yaj kiab hluav taws xob thiab cov tshuab ua kom muaj zog yog sib npaug nrog cov yeeb yaj kiab uas siv tshuaj vapor deposition (CVD).
Txhua yam khoom siv hluav taws xob tsim hluav taws xob EM. Raws li cov cuab yeej ua tau me me thiab ua haujlwm ntawm ntau dua thiab ntau dua, qhov muaj peev xwm rau electromagnetic cuam tshuam (EMI) loj tuaj, thiab tuaj yeem cuam tshuam rau kev ua haujlwm ntawm lub cuab yeej nrog rau cov khoom siv hluav taws xob nyob ze.
Graphite, ib qho allotrope ntawm carbon ua los ntawm cov khaubncaws sab nraud povtseg ntawm graphene tuav ua ke los ntawm van der Waals rog, muaj ib tug xov tooj ntawm zoo kawg li hluav taws xob, thermal thiab mechanical zog uas ua rau nws ib tug zoo tiv thaiv EMI. Txawm li cas los xij, nws yuav tsum muaj nyob rau hauv daim ntawv ntawm cov zaj duab xis nyias heev rau nws kom muaj hluav taws xob zoo, uas yog qhov tseem ceeb rau kev siv EMI vim tias nws txhais tau hais tias cov khoom tuaj yeem cuam tshuam thiab nqus EM nthwv dej thaum lawv cuam tshuam nrog cov neeg nqa khoom hauv. nws.
Tam sim no, txoj hauv kev tseem ceeb ntawm kev ua graphite zaj duab xis koom nrog qhov kub-kub pyrolysis ntawm aromatic polymers los yog stacking graphene (GO) oxide los yog graphene nanosheets txheej los ntawm txheej. Ob txheej txheem yuav tsum tau kub ntawm ib ncig ntawm 3000 ° C thiab ua lub sij hawm ntawm ib teev. Hauv CVD, qhov ntsuas kub yuav tsum tau qis dua (nruab nrab ntawm 700 txog 1300 ° C), tab sis nws yuav siv sij hawm ob peb teev los ua cov yeeb yaj kiab nanometer-thick, txawm tias hauv lub tshuab nqus tsev.
Ib pab neeg coj los ntawm Wencai Ren tam sim no tau tsim cov graphite zaj duab xis zoo kaum ntawm nanometers tuab li ntawm ob peb vib nas this los ntawm cua kub npib tsib xee rau 1200 ° C nyob rau hauv ib qho chaw argon thiab ces immersing cov ntawv ci hauv ethanol ntawm 0 ° C. Cov pa roj carbon atoms tsim los ntawm decomposition ntawm ethanol diffuse thiab yaj rau hauv cov npib tsib xee ua tsaug rau cov hlau cov pa roj carbon ntau solubility (0.4 wt% ntawm 1200 ° C). Vim tias cov pa roj carbon solubility no txo qis ntawm qhov kub thiab txias, cov pa roj carbon atoms tom qab sib cais thiab precipitate los ntawm npib tsib xee nto thaum quenching, ua ib tug tuab graphite zaj duab xis. Cov kws tshawb fawb tau tshaj tawm tias cov kev ua haujlwm catalytic zoo heev ntawm npib tsib xee kuj pab tsim cov crystalline graphite heev.
Siv kev sib xyaw ua ke ntawm cov kev daws teeb meem xa mus rau microscopy, X-ray diffraction thiab Raman spectroscopy, Ren thiab cov npoj yaig pom tias cov graphite uas lawv tsim tau yog crystalline heev nyob rau thaj tsam loj, txheej txheej zoo thiab tsis muaj qhov tsis pom kev. Cov electron conductivity ntawm cov yeeb yaj kiab yog siab li 2.6 x 105 S / m, zoo ib yam li cov yeeb yaj kiab loj hlob los ntawm CVD lossis cov txheej txheem kub kub thiab nias ntawm GO / graphene films.
Txhawm rau kuaj seb cov khoom puas tuaj yeem thaiv cov hluav taws xob EM, pab pawg tau xa cov yeeb yaj kiab nrog thaj tsam ntawm 600 mm2 mus rau substrates ua los ntawm polyethylene terephthalate (PET). Lawv mam li ntsuas cov yeeb yaj kiab EMI tiv thaiv kev ua tau zoo (SE) hauv X-band zaus, ntawm 8.2 thiab 12.4 GHz. Lawv pom EMI SE ntau dua 14.92 dB rau ib zaj duab xis kwv yees li 77 nm tuab. Tus nqi no nce mus rau ntau dua 20 dB (tus nqi yam tsawg kawg nkaus uas yuav tsum tau siv rau kev lag luam kev lag luam) hauv tag nrho X-band thaum lawv tso ntau cov yeeb yaj kiab ua ke. Tseeb, ib zaj duab xis uas muaj tsib daim ntawm cov graphite films (nyob ib ncig ntawm 385 nm tuab nyob rau hauv tag nrho) muaj EMI SE ntawm ib ncig ntawm 28 dB, uas txhais tau hais tias cov khoom yuav thaiv tau 99.84% ntawm qhov teeb meem hluav taws xob. Zuag qhia tag nrho, pab pawg tau ntsuas EMI tiv thaiv ntawm 481,000 dB / cm2 / g thoob plaws X-band, ua tau zoo tshaj txhua yam khoom siv uas tau tshaj tawm yav dhau los.
Cov kws tshawb fawb tau hais tias kom ua tau zoo tshaj plaws ntawm lawv txoj kev paub, lawv cov graphite zaj duab xis yog qhov thinnest ntawm cov ntaub thaiv npog, nrog rau EMI shielding kev ua tau zoo uas tuaj yeem ua tau raws li qhov yuav tsum tau ua rau kev lag luam. Nws cov khoom siv kho tshuab kuj muaj txiaj ntsig zoo. Cov khoom siv lub zog tawg ntawm kwv yees li 110 MPa (extracted los ntawm kev ntxhov siab-strain curves ntawm cov khoom muab tso rau hauv ib qho kev txhawb nqa polycarbonate) yog siab dua li ntawm graphite films zus los ntawm lwm txoj kev. Cov yeeb yaj kiab yog hloov tau, ib yam nkaus, thiab tuaj yeem khoov 1000 zaug nrog lub vojvoog dabtsi yog khoov ntawm 5 hli yam tsis tau poob nws cov khoom tiv thaiv EMI. Nws kuj yog thermally ruaj khov mus txog 550 ° C. Pab neeg no ntseeg tias cov khoom no thiab lwm yam txhais tau hais tias nws tuaj yeem siv los ua ib qho ultrathin, hnav, yoog raws thiab siv tau zoo EMI shielding khoom siv rau ntau qhov chaw, suav nrog aerospace thiab electronics thiab optoelectronics.
Nyeem qhov kev nce qib tseem ceeb tshaj plaws thiab zoo siab tshaj plaws hauv cov ntaub ntawv tshawb fawb hauv phau ntawv qhib tshiab no.
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Post lub sij hawm: May-07-2020