Ua tsaug rau koj txoj kev sau npe nrog Physics World Yog tias koj xav hloov koj cov ntaub ntawv txhua lub sijhawm, thov mus saib Kuv tus account
Cov yeeb yaj kiab graphite tuaj yeem tiv thaiv cov khoom siv hluav taws xob los ntawm hluav taws xob electromagnetic (EM), tab sis cov txheej txheem tam sim no rau kev tsim lawv siv sijhawm ntau teev thiab xav tau qhov kub ua tiav ntawm kwv yees li 3000 ° C. Ib pab pawg kws tshawb fawb los ntawm Shenyang National Laboratory for Materials Science ntawm Suav Academy of Sciences tam sim no tau ua pov thawj lwm txoj hauv kev los ua cov yeeb yaj kiab graphite zoo hauv ob peb feeb xwb los ntawm kev tua cov ntawv ci kub ntawm nickel hauv ethanol. Tus nqi loj hlob rau cov yeeb yaj kiab no yog ntau dua ob qho kev txiav txim siab ntawm qhov loj dua li cov txheej txheem uas twb muaj lawm, thiab cov yeeb yaj kiab 'electrical conductivity thiab mechanical zog yog nyob rau hauv par nrog cov yeeb yaj kiab ua los ntawm kev siv cov tshuaj lom neeg vapor deposition (CVD).
Txhua yam khoom siv hluav taws xob tsim tawm qee qhov hluav taws xob EM. Thaum cov khoom siv me dua thiab ua haujlwm ntawm qhov zaus siab dua, qhov muaj peev xwm rau kev cuam tshuam hluav taws xob (EMI) loj hlob tuaj, thiab tuaj yeem cuam tshuam tsis zoo rau kev ua haujlwm ntawm lub cuab yeej nrog rau cov kab ke hluav taws xob nyob ze.
Graphite, ib qho allotrope ntawm cov pa roj carbon uas ua los ntawm cov txheej ntawm graphene tuav ua ke los ntawm van der Waals rog, muaj ntau yam khoom siv hluav taws xob, thermal thiab mechanical zoo kawg uas ua rau nws yog ib qho tiv thaiv zoo tiv thaiv EMI. Txawm li cas los xij, nws yuav tsum nyob rau hauv daim ntawv ntawm ib zaj duab xis nyias heev rau nws kom muaj kev coj hluav taws xob siab, uas yog qhov tseem ceeb rau kev siv EMI vim nws txhais tau tias cov khoom siv tuaj yeem cuam tshuam thiab nqus cov nthwv dej EM thaum lawv cuam tshuam nrog cov neeg nqa khoom hauv nws.
Tam sim no, cov txoj hauv kev tseem ceeb ntawm kev ua cov yeeb yaj kiab graphite suav nrog kev kub siab pyrolysis ntawm cov polymers aromatic lossis kev sib sau ua ke graphene (GO) oxide lossis graphene nanosheets txheej los ntawm txheej. Ob qho txheej txheem xav tau qhov kub siab ntawm kwv yees li 3000 ° C thiab lub sijhawm ua tiav ntawm ib teev. Hauv CVD, qhov kub uas xav tau qis dua (ntawm 700 txog 1300 ° C), tab sis nws siv sijhawm ob peb teev los ua cov yeeb yaj kiab nanometer-tuab, txawm tias nyob hauv lub tshuab nqus tsev.
Ib pab neeg uas Wencai Ren coj tau tam sim no tau tsim cov zaj duab xis graphite zoo uas tuab kaum nanometers hauv ob peb feeb los ntawm kev ua kom cov ntawv ci nickel sov txog 1200 ° C hauv huab cua argon thiab tom qab ntawd muab cov ntawv ci no tso rau hauv ethanol sai sai ntawm 0 ° C. Cov pa roj carbon uas tsim los ntawm kev lwj ntawm ethanol diffuse thiab yaj rau hauv nickel ua tsaug rau cov hlau qhov solubility carbon siab (0.4 wt% ntawm 1200 ° C). Vim tias qhov solubility carbon no txo qis heev ntawm qhov kub qis, cov pa roj carbon tom qab ntawd sib cais thiab precipitate ntawm qhov chaw nickel thaum lub sijhawm quenching, tsim cov zaj duab xis graphite tuab. Cov kws tshawb fawb tshaj tawm tias qhov kev ua haujlwm catalytic zoo heev ntawm nickel kuj pab tsim cov graphite crystalline heev.
Siv kev sib xyaw ua ke ntawm kev siv lub tshuab microscopy siab, X-ray diffraction thiab Raman spectroscopy, Ren thiab cov npoj yaig pom tias cov graphite uas lawv tsim tau yog cov khoom siv crystalline ntau heev hla thaj chaw loj, zoo txheej thiab tsis muaj qhov tsis zoo pom. Lub zog hluav taws xob ntawm cov yeeb yaj kiab yog siab txog 2.6 x 105 S / m, zoo ib yam li cov yeeb yaj kiab uas cog los ntawm CVD lossis cov txheej txheem kub siab thiab nias cov yeeb yaj kiab GO / graphene.
Yuav kom sim seb cov khoom siv no thaiv tau hluav taws xob EM zoo npaum li cas, pab pawg neeg tau hloov cov yeeb yaj kiab uas muaj thaj tsam ntawm 600 mm2 mus rau cov khoom siv ua los ntawm polyethylene terephthalate (PET). Tom qab ntawd lawv ntsuas qhov ua tau zoo ntawm EMI shielding (SE) ntawm zaj duab xis hauv X-band zaus, ntawm 8.2 thiab 12.4 GHz. Lawv pom EMI SE ntau dua 14.92 dB rau zaj duab xis uas tuab li 77 nm. Tus nqi no nce mus txog ntau dua 20 dB (tus nqi tsawg kawg nkaus uas xav tau rau kev siv lag luam) hauv tag nrho X-band thaum lawv muab ntau zaj duab xis sib sau ua ke. Tseeb tiag, ib zaj duab xis uas muaj tsib daim zaj duab xis graphite sib sau ua ke (kwv yees li 385 nm tuab tag nrho) muaj EMI SE li ntawm 28 dB, uas txhais tau tias cov khoom siv no tuaj yeem thaiv tau 99.84% ntawm hluav taws xob. Tag nrho, pab pawg neeg tau ntsuas EMI shielding ntawm 481,000 dB/cm2/g thoob plaws X-band, ua tau zoo dua txhua yam khoom siv hluavtaws uas tau tshaj tawm yav dhau los.
Cov kws tshawb fawb hais tias raws li lawv txoj kev paub, lawv cov zaj duab xis graphite yog cov khoom nyias tshaj plaws ntawm cov ntaub ntawv tiv thaiv, nrog rau kev ua haujlwm tiv thaiv EMI uas tuaj yeem ua tau raws li qhov xav tau rau kev siv lag luam. Nws cov khoom siv kho tshuab kuj zoo. Lub zog tawg ntawm cov khoom siv kwv yees li 110 MPa (rho tawm ntawm cov kab kev ntxhov siab-strain ntawm cov khoom siv tso rau ntawm kev txhawb nqa polycarbonate) yog siab dua li cov yeeb yaj kiab graphite uas loj hlob los ntawm lwm txoj kev. Cov yeeb yaj kiab kuj tseem yoog tau, thiab tuaj yeem khoov 1000 zaug nrog lub vojvoog khoov ntawm 5 hli yam tsis poob nws cov khoom tiv thaiv EMI. Nws kuj tseem ruaj khov txog li 550 ° C. Pab neeg ntseeg tias cov no thiab lwm yam khoom txhais tau tias nws tuaj yeem siv ua cov khoom tiv thaiv EMI ultrathin, sib dua, yoog tau thiab zoo rau kev siv hauv ntau qhov chaw, suav nrog aerospace nrog rau electronics thiab optoelectronics.
Nyeem cov kev nce qib tseem ceeb thiab zoo siab tshaj plaws hauv kev tshawb fawb txog cov ntaub ntawv hauv phau ntawv xov xwm tshiab no.
Physics World yog ib feem tseem ceeb ntawm IOP Publishing lub hom phiaj los sib txuas lus txog kev tshawb fawb thiab kev tsim kho tshiab thoob ntiaj teb rau cov neeg tuaj saib ntau tshaj plaws. Lub vev xaib no yog ib feem ntawm Physics World portfolio, uas yog cov kev pabcuam online, digital thiab luam tawm rau lub zej zog kev tshawb fawb thoob ntiaj teb.
Lub sijhawm tshaj tawm: Tsib Hlis-07-2020