Yawancin ’yan wasa a duniya waɗanda suka ɗanɗana zamanin Xbox 360 sun san halin da ake ciki sosai lokacin da na'urar na'urarsu ta juya zuwa kaskon soya wanda akan soya ƙwai. Irin wannan yanayin bakin ciki yana faruwa ba kawai tare da na'urorin wasan bidiyo ba, har ma da wayoyi, kwamfutar tafi-da-gidanka, kwamfutar hannu da ƙari mai yawa. A ka'ida, kusan kowane na'ura na lantarki na iya fuskantar girgizar zafi, wanda zai iya haifar da ba kawai ga gazawarsa da fushin mai shi ba, amma har zuwa "mummunan haɓaka" na baturi da mummunan rauni. A yau za mu saba da wani binciken da masana kimiyya daga Jami’ar Stanford, kamar Nick Fury daga cikin fina-finan barkwanci, suka samar da wata garkuwa da ke ba da kariya ga sassan lantarki masu zafin zafi daga zazzaɓi kuma, sakamakon haka, ke hana rushewar su. Ta yaya masana kimiyya suka yi nasarar ƙirƙirar garkuwar thermal, menene manyan abubuwan da ke tattare da shi kuma yaya tasiri yake? Mun koyi game da wannan da ƙari daga rahoton ƙungiyar bincike. Tafi
Tushen bincike
An dade da sanin matsalar zafi fiye da kima, kuma masana kimiyya suna magance ta ta hanyoyi daban-daban. Wasu daga cikin shahararrun su ne amfani da gilashi, filastik har ma da yadudduka na iska, wanda ke aiki a matsayin nau'in insulators na thermal radiation. A hakikanin zamani, ana iya inganta wannan hanyar ta hanyar rage kauri daga cikin kauri mai karewa zuwa kwayoyin halitta da yawa ba tare da rasa abubuwan da ke da zafi ba. Abin da masu binciken suka yi ke nan.
Muna, ba shakka, muna magana ne game da nanomaterials. Duk da haka, amfani da su a cikin rufin thermal ya kasance mai rikitarwa a baya ta gaskiyar cewa tsawon lokacin sanyi (phonon*) ya fi na electrons ko photon gajarta sosai.
phonon* - Quasiparticle, wanda adadi ne na motsin girgizar atom na crystal.
Bugu da kari, saboda yanayin bosonic na phonons, ba zai yuwu a sarrafa su ta hanyar wutar lantarki (kamar yadda ake yi da masu ɗaukar kaya), wanda gabaɗaya yana da wahala a iya sarrafa yanayin zafi a cikin daskararru.
A baya can, da thermal Properties na daskararru, kamar yadda masu bincike tunatar da mu, an sarrafa ta hanyar nanolaminate fina-finai da superlatices saboda tsarin cuta da kuma high yawa musaya, ko ta hanyar silicon da germanium nanowires saboda karfi phonon watsawa.
Zuwa da yawa daga cikin hanyoyin rufin da aka bayyana a sama, masana kimiyya suna shirye don danganta kayan kwalliya biyu, wanda ya sa su sauƙaƙe iko da sikelin atomom. A cikin binciken da suka yi amfani da su van der Waals (vdW) haduwar siraran 2D na atomically don cimma babban juriya na thermal a duk tsawon tsarin halittarsu.
Van der Waals Forces* - Ƙungiyoyin hulɗar intermolecular / interatomic tare da makamashi na 10-20 kJ / mol.
Sabuwar dabarar ta ba da damar samun juriya na thermal a cikin 2nm kauri vdW heterostructure mai kwatankwacin wannan a cikin 2nm mai kauri SiO300 (silicon dioxide) Layer.
Bugu da kari, amfani da vdW heterostructures ya ba da damar samun iko a kan thermal kaddarorin a matakin atomic ta hanyar shimfidar nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan XNUMXD tare da nau'ikan nau'ikan atomic daban-daban da yanayin girgiza.
Don haka, kada mu ja ramin cat kuma bari mu fara la'akari da sakamakon wannan bincike mai ban mamaki.
Sakamakon bincike
Da farko, bari mu san ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun kayan aikin vdW da aka yi amfani da su a cikin wannan binciken.
Hoto #1
Akan hoton 1 yana nuna zane-zanen giciye na heterostructure mai Layer huɗu wanda ya ƙunshi (daga sama zuwa ƙasa): graphene (Gr), MoSe2, MoS2, WSe22 da SiO2/Si substrate. Don duba duk yadudduka lokaci guda, yi amfani Raman Laser* tare da tsawon 532 nm.
Raman Laser* - nau'in Laser wanda babban tsarin haɓaka haske shine watsawar Raman.
Raman watsawa, bi da bi, shi ne inelastic watsawa na gani radiation a kan kwayoyin halitta na wani abu, wanda yake tare da gagarumin canji a cikin mita na radiation.
An yi amfani da hanyoyi da yawa don tabbatar da daidaituwar microstructural, thermal da wutar lantarki na heterostructures: duban dan tayi watsawar microscopy (STEM), photoluminescence spectroscopy (PL), Kelvin probe microscopy (KPM), scanning thermal microscopy (SThM), kazalika da Raman spectroscopy thermometry .
Hoto 1b yana nuna mana bakan Raman na Gr/MoSe2/MoS2/WSe22 heterostructure akan siO2/Si substrate a wurin da aka yiwa alamar ja. Wannan mãkirci yana nuna sa hannun kowane monolayer a cikin jeri na Layer, da kuma sa hannun Si substrate.
a kan 1c-1f An nuna hotunan STEM mai duhu na Gr/MoSe2/MoS2/WSe221s) da Gr/MoS2/WSe22 heterostructures (1d-1f) tare da mabanbantan lattice. Hotunan STEM suna nuna gibin vdW kusa da atomatik ba tare da wani gurɓata ba, yana barin gabaɗayan kauri na waɗannan nau'ikan gine-gine su zama cikakke. An kuma tabbatar da kasancewar haɗin haɗin gwiwa a kan manyan wuraren dubawa ta amfani da hoton hoto (PL) spectroscopy (1g). Siginar hotoluminescent na kowane yadudduka a cikin heterostructure yana da matuƙar danne idan aka kwatanta da siginar keɓantaccen monolayer. Ana bayanin wannan ta hanyar hanyar canja wurin cajin interlayer saboda kusancin hulɗar interlayer, wanda ke ƙara ƙarfi bayan annealing.
Hoto #2
Domin auna zafin zafi daidai gwargwado zuwa jiragen atomic na heterostructure, an tsara tsarar yadudduka a cikin nau'in na'urorin lantarki masu bincike huɗu. Babban Layer na graphene yana hulɗa da na'urorin lantarki na palladium (Pd) kuma ana amfani dashi azaman dumama don ma'aunin ma'aunin zafin jiki na Raman.
Wannan hanyar dumama wutar lantarki tana ba da madaidaicin ƙididdige ƙarfin shigarwar. Wata hanyar dumama mai yuwuwa, mai gani, zai zama mafi wahalar aiwatarwa saboda jahilcin abubuwan sha na kowane yadudduka.
a kan 2 yana nuna da'irar ma'aunin bincike huɗu, da 2b yana nuna babban ra'ayi na tsarin da ake gwadawa. Jadawalin 2s yana nuna halayen canja wurin zafi don na'urori uku, ɗaya mai ɗauke da graphene kawai da biyu mai ɗauke da Gr/WSe22 da Gr/MoSe2/WSe22 Layer arrays. Duk bambance-bambancen suna nuna halayen ambipolar na graphene, wanda ke da alaƙa da rashin ratar bandeji.
An kuma gano cewa gudanarwa na yanzu da dumama suna faruwa a cikin babban Layer (a cikin graphene), tun da wutar lantarkin ta yana da umarni da yawa na girma fiye da na MoS2 da WSe22.
Don nuna kamanni na na'urorin da aka gwada, an ɗauki ma'auni ta amfani da Kelvin probe microscopy (KPM) da kuma duban yanayin zafi (SThM). A kan ginshiƙi 2d Ana nuna ma'aunin KPM wanda ke nuna yuwuwar rarrabawar layi. Ana nuna sakamakon binciken SthM a ciki 2s. Anan muna ganin taswirar tashoshi na Gr/MoS2/WSe22 masu zafi da lantarki, da kuma kasancewar daidaito a cikin dumama ƙasa.
Dabarun binciken da aka kwatanta a sama, musamman SthM, sun tabbatar da kamannin tsarin da ake nazari, wato, kamanninsa, dangane da yanayin zafi. Mataki na gaba shine ƙididdige yawan zafin jiki na kowane nau'in yadudduka ta amfani da Raman spectroscopy (watau Raman spectroscopy).
An gwada dukkan na'urori guda uku, kowanne yana da yanki na ~40 µm2. A wannan yanayin, wutar lantarki ta canza ta 9mW, kuma ikon laser mai ɗaukar nauyi ya kasance ƙasa ~ 5 μW tare da wurin tabo Laser na ~ 0.5 μm2.
Hoto #3
A kan ginshiƙi 3 karuwa a zafin jiki (∆T) na kowane Layer da substrate yana bayyane yayin da wutar lantarki a cikin Gr/MoS2/WSe22 heterostructure ke ƙaruwa.
Matsakaicin aikin layi na kowane abu (Layer) yana nuna juriya na thermal (Rth = ∆ T / P) tsakanin nau'in mutum ɗaya da zafin rana. Idan aka ba da daidaiton rarraba dumama a kan yankin, ana iya sauƙaƙe juriya na thermal daga ƙasa zuwa saman Layer, yayin da ƙimar su ta daidaita ta yankin tashar (WL).
L da W sune tsayin tashar da nisa, waɗanda suke da mahimmanci fiye da kauri na SiO2 substrate da tsayin zafin zafi na gefe, wanda shine ~ 0.1 μm.
Don haka, zamu iya samun dabarar juriya na thermal na Si substrate, wanda zai yi kama da haka:
Rth, Si ≈ (WL) 1/2 / (2kSi)
A cikin wannan hali kSi ≈ 90 W m-1 K-1, wanda shine tsammanin zazzagewar yanayin zafi na irin wannan nau'in doped.
Bambanci tsakanin Rth, WSe2 da Rth, Si shine jimlar juriya na thermal na 2nm lokacin farin ciki SiO100 da juriya na thermal (TBR) na haɗin WSe2/SiO2.
Haɗa duk abubuwan da ke sama tare, zamu iya kafa cewa Rth, MoS2 - Rth, WSe2 = TBRMoS2/WSe2, da Rth, Gr - Rth, MoS2 = TBRGr/MoS2. Saboda haka, daga jadawali 3 yana yiwuwa a cire ƙimar TBR don kowane ɗayan musaya na WSe2/SiO2, MoS2/Wse2 da Gr/MoS2.
Bayan haka, masanan kimiyya sun kwatanta jimlar juriya na thermal na duk heterostructures, auna ta amfani da Raman spectroscopy da thermal microscopy.3b).
Bilayer da trilayer heterostructures a kan SiO2 sun nuna ingantaccen juriya na thermal a cikin kewayon 220 zuwa 280 m2 K/GW a dakin da zafin jiki, wanda yayi daidai da juriya na thermal na SiO2 tare da kauri na 290 zuwa 360 nm. Duk da cewa kauri na heterostructures a karkashin binciken bai wuce 2 nm ba (1d-1f), Matsayin zafin su shine 0.007-0.009 W m-1 K-1 a dakin da zafin jiki.
Hoto #4
Hoto na 4 yana nuna ma'auni na dukkanin sifofi guda huɗu da ma'aunin iyakoki na thermal (TBC) na musayansu, wanda ke ba mu damar kimanta girman tasirin kowane Layer akan juriya na thermal da aka auna a baya (TBC = 1 / TBR).
Masu binciken sun lura cewa wannan shine ma'aunin TBC-na farko don mu'amalar atomically kusa da keɓaɓɓun masu rarrafe (2D/2D), musamman tsakanin WSe2 da SiO2 monolayers.
TBC na wani monolayer WSe2/SiO2 interface yayi ƙasa da na WSe2/SiO2 interface multilayer, wanda ba abin mamaki bane tunda monolayer yana da ƙarancin lanƙwasa hanyoyin phonon don watsawa. A sauƙaƙe, TBC na mu'amala tsakanin 2D yadudduka yana ƙasa da TBC na mu'amala tsakanin Layer 2D da 3D SiO2 substrate (4b).
Don ƙarin cikakken sani tare da nuances na binciken, Ina ba da shawarar dubawa и masa.
Epilogue
Wannan bincike, kamar yadda su kansu masana kimiyya suka yi iƙirari, yana ba mu ilimin da za a iya amfani da shi wajen aiwatar da mu'amalar wutar lantarki ta atomatik. Wannan aikin ya nuna yiwuwar ƙirƙirar metamaterials masu hana zafi waɗanda ba a samo kaddarorinsu a cikin yanayi ba. Bugu da kari, binciken ya kuma tabbatar da yiwuwar aiwatar da ma'aunin zafin jiki na irin wadannan sifofin, duk da ma'aunin atomic na yadudduka.
Heterostructures da aka bayyana a sama na iya zama tushen maɗaukakiyar haske da ƙaƙƙarfan "garkuwan" thermal, masu iya, alal misali, cire zafi daga wurare masu zafi a cikin kayan lantarki. Bugu da ƙari, ana iya amfani da wannan fasaha a cikin masu samar da wutar lantarki ko na'urori masu sarrafa zafin jiki, ƙara yawan aikin su.
Wannan binciken ya sake tabbatar da cewa kimiyyar zamani tana da matukar sha'awar ka'idar "inganci a cikin thmble," wanda ba za a iya kira shi da ra'ayin wawa ba, idan aka ba da iyakacin albarkatun duniya da ci gaba da ci gaba da buƙatar kowane nau'i na fasaha na fasaha.
Na gode da hankalin ku, ku kasance da sha'awar kuma ku sami mako mai kyau kowa da kowa! 🙂
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source: www.habr.com