Mahalo no kou hoʻopaʻa inoa ʻana me Physics World Inā makemake ʻoe e hoʻololi i kāu ʻike i kēlā me kēia manawa, e kipa i kaʻu moʻokāki.
Hiki i nā kiʻiʻoniʻoni graphite ke pale i nā mea uila mai ka radiation electromagnetic (EM), akā ʻo nā ʻano hana o kēia manawa no ka hana ʻana iā lākou e lawe i kekahi mau hola a koi i nā mahana hana ma kahi o 3000 °C. Ua hōʻike ʻia kahi hui o nā mea noiʻi mai ka Shenyang National Laboratory for Materials Science ma ka Chinese Academy of Sciences i kahi ala ʻē aʻe e hana ai i nā kiʻiʻoniʻoni graphite kiʻekiʻe i loko o kekahi mau kekona wale nō ma ka hoʻopau ʻana i nā ʻāpana wela o ka pepa nickel i loko o ka ethanol. ʻOi aku ka nui o ka ulu ʻana no kēia mau kiʻiʻoniʻoni ma mua o ʻelua mau kauoha o ka nui ma mua o nā ʻano hana i loaʻa, a ʻo ka conductivity uila a me ka ikaika mechanical o nā kiʻiʻoniʻoni e like me nā kiʻiʻoniʻoni i hana ʻia me ka hoʻohana ʻana i ka chemical vapour deposition (CVD).
Hoʻopuka nā mea uila a pau i kekahi kukuna EM. I ka liʻiliʻi ʻana o nā mea hana a hana i nā alapine kiʻekiʻe a kiʻekiʻe aʻe, ulu ka hiki ke hoʻopilikia i ka electromagnetic (EMI), a hiki ke hoʻopilikia maikaʻi ʻole i ka hana o ka mea hana a me nā ʻōnaehana uila kokoke.
ʻO Graphite, kahi allotrope o ke kalapona i kūkulu ʻia mai nā papa o ka graphene i hoʻopaʻa ʻia e nā mana van der Waals, he nui nā waiwai uila, wela a me nā mechanical kupaianaha e lilo ai ia i pale pale kūpono e kūʻē i ka EMI. Eia nō naʻe, pono ia ma ke ʻano o kahi ʻili lahilahi loa i mea e loaʻa ai kahi conductivity uila kiʻekiʻe, he mea nui ia no nā noi EMI kūpono no ka mea ʻo ia hoʻi hiki i ka mea ke hōʻike a omo i nā nalu EM i ko lākou launa pū ʻana me nā mea lawe ukana i loko.
I kēia manawa, ʻo nā ala nui o ka hana ʻana i ka ʻili graphite e pili ana i ka pyrolysis wela kiʻekiʻe o nā polymers aromatic a i ʻole ka hoʻopili ʻana i ka graphene (GO) oxide a i ʻole nā nanosheets graphene papa ma ka papa. Pono nā kaʻina hana ʻelua i nā mahana kiʻekiʻe ma kahi o 3000 °C a me nā manawa hana o hoʻokahi hola. I ka CVD, ʻoi aku ka haʻahaʻa o nā mahana i koi ʻia (ma waena o 700 a 1300 °C), akā he mau hola ka lōʻihi e hana ai i nā ʻili nanometer-mānoanoa, ʻoiai i loko o ka vacuum.
Ua hana kekahi hui i alakaʻi ʻia e Wencai Ren i kahi kiʻiʻoniʻoni graphite kiʻekiʻe he ʻumi nanometers ka mānoanoa i loko o kekahi mau kekona ma ka hoʻomehana ʻana i ka pepa nickel a i 1200 °C i loko o kahi lewa argon a laila hoʻokomo koke i kēia pepa i loko o ka ethanol ma 0 °C. Hoʻolaha a hoʻoheheʻe ʻia nā ʻātoma kalapona i hana ʻia mai ka decomposition o ka ethanol i loko o ka nickel mahalo i ke kalapona kiʻekiʻe o ka metala (0.4 wt% ma 1200 °C). Ma muli o ka emi nui ʻana o kēia kalapona i ka mahana haʻahaʻa, hoʻokaʻawale nā ʻātoma kalapona a hoʻokahe ʻia mai ka ʻili nickel i ka wā o ka quenching, e hana ana i kahi kiʻiʻoniʻoni graphite mānoanoa. Hōʻike nā mea noiʻi ʻo ka hana catalytic maikaʻi loa o ka nickel e kōkua pū i ka hoʻokumu ʻana o ka graphite crystalline kiʻekiʻe.
Ma ka hoʻohana ʻana i ka hui pū ʻana o ka microscopy hoʻoili kiʻekiʻe-hoʻonā, ka diffraction X-ray a me ka spectroscopy Raman, ua ʻike ʻo Ren a me nā hoa hana he crystalline kiʻekiʻe ka graphite a lākou i hana ai ma luna o nā wahi nui, ua papa maikaʻi ʻia a ʻaʻohe hemahema i ʻike ʻia. ʻO ke alakaʻi uila o ke kiʻiʻoniʻoni he kiʻekiʻe e like me 2.6 x 105 S/m, like me nā kiʻiʻoniʻoni i ulu ʻia e CVD a i ʻole nā ʻenehana wela kiʻekiʻe a me ke kaomi ʻana o nā kiʻiʻoniʻoni GO/graphene.
No ka hoʻāʻo ʻana i ka maikaʻi o ka pale ʻana o ka mea i ka radiation EM, ua hoʻoili ka hui i nā kiʻiʻoniʻoni me ka ʻili o 600 mm2 ma luna o nā substrates i hana ʻia me ka polyethylene terephthalate (PET). A laila ua ana lākou i ka pono pale EMI (SE) o ke kiʻiʻoniʻoni ma ka pae alapine X-band, ma waena o 8.2 a me 12.4 GHz. Ua loaʻa iā lākou kahi EMI SE ma mua o 14.92 dB no kahi kiʻiʻoniʻoni ma kahi o 77 nm ka mānoanoa. Hoʻonui kēia waiwai i ʻoi aku ma mua o 20 dB (ka waiwai liʻiliʻi loa e pono ai no nā noi kalepa) ma ka X-band holoʻokoʻa i ka wā i hoʻopili ai lākou i nā kiʻiʻoniʻoni hou aku. ʻOiaʻiʻo, ʻo kahi kiʻiʻoniʻoni e loaʻa ana i ʻelima mau ʻāpana o nā kiʻiʻoniʻoni graphite i hoʻopili ʻia (ma kahi o 385 nm ka mānoanoa) he EMI SE ma kahi o 28 dB, ʻo ia hoʻi, hiki i ka mea ke pale i 99.84% o ka radiation incident. Ma keʻano holoʻokoʻa, ua ana ka hui i kahi pale EMI o 481,000 dB/cm2/g ma waena o ka X-band, e ʻoi aku ka maikaʻi ma mua o nā mea synthetic i hōʻike mua ʻia.
Ua ʻōlelo nā kānaka noiʻi, i ko lākou ʻike maikaʻi loa, ʻo kā lākou kiʻiʻoniʻoni graphite ka mea lahilahi loa i waena o nā mea pale i hōʻike ʻia, me kahi hana pale EMI e hiki ke hoʻokō i ke koi no nā noi kalepa. He maikaʻi nō hoʻi kona mau waiwai mechanical. ʻOi aku ka ikaika o ka haki o ka mea ma kahi o 110 MPa (i unuhi ʻia mai nā piʻo stress-strain o ka mea i kau ʻia ma ke kākoʻo polycarbonate) ma mua o nā kiʻiʻoniʻoni graphite i ulu ʻia e nā ʻano hana ʻē aʻe. He maʻalahi hoʻi ke kiʻiʻoniʻoni, a hiki ke pelu ʻia i 1000 mau manawa me ka radius pelu o 5 mm me ka nalowale ʻole o kona mau waiwai pale EMI. He paʻa hoʻi ia i ka wela a hiki i 550 °C. Manaʻo ka hui ʻo kēia mau waiwai a me nā waiwai ʻē aʻe ke ʻano he mea pale EMI ultrathin, māmā, maʻalahi a maikaʻi hoʻi no nā noi ma nā wahi he nui, me ka aerospace a me nā electronics a me optoelectronics.
E heluhelu i nā holomua koʻikoʻi a hoihoi loa i ka ʻepekema mea hana ma kēia puke pai wehe hou.
He ʻāpana koʻikoʻi ʻo Physics World o ka misionari a IOP Publishing e hoʻolaha i ka noiʻi a me ka hana hou o ka honua i ka lehulehu ākea loa. ʻO ka pūnaewele kekahi ʻāpana o ka waihona Physics World, kahi hōʻiliʻili o nā lawelawe ʻike pūnaewele, kikohoʻe a me ka paʻi no ke kaiāulu ʻepekema honua.
Ka manawa hoʻouna: Mei-07-2020