Pob zeb diamond thiab graphite: lub ntiaj teb ntxim nyiam ntawm ob feem

Nyob rau hauv peb lub neej niaj hnub, carbon muaj nyob rau hauv ntau hom, feem ntau zoo-paub ntawm uas yog graphite nyob rau hauv mem hluav coj thiab dazzling pob zeb diamond - pob zeb diamond. Txawm hais tias lawv tau muab los ntawm tib lub ntsiab lus, cov khoom ntawm lub cev ntawm ob qhov sib txawv heev, los ntawm cov xim, hardness mus rau melting point, qhia txog ntau haiv neeg thiab khawv koob ntawm carbon.

Cov qauv sib txawv: kev sib txawv ntawm macroscopic los ntawm cov ntawv me me

Pob zeb diamond thiab graphite yog ob qho tib si ua los ntawm carbon atoms txuas nrog covalent bonds, tab sis lawv cov kev npaj sib txawv kiag li. Pob zeb diamond yog qhov nyuaj dua li graphite vim tias cov pa roj carbon atoms hauv pob zeb diamond tau teeb tsa hauv cov qauv tetrahedral, thiab txhua cov pa roj carbon atom txuas nrog plaub lwm cov pa roj carbon atom, tsim ib qho nyuaj heev thiab tsis sib xws spatial network qauv. Txawm hais tias qhov kev taw qhia ntawm lub zog sab nraud yog siv, ntau cov nyiaj sib cog lus yuav tsum tau tawg rau tib lub sijhawm kom deform lossis tawg.

 

Nyob rau hauv sib piv, cov qauv ntawm graphite zoo li muaj ntau "xoob". Cov pa roj carbon atoms hauv graphite yog teem rau hauv cov khaubncaws sab nraud povtseg, thiab cov pa hluav taws xob hauv txhua qhov kev sib txuas lus los ntawm cov khoom sib txuas los ntawm wall werer van der woults rog. Qhov kev ncua deb ntawm cov khaubncaws sab nraud pov tseg thiab lub zog tsis muaj zog heev, yog li nws yooj yim "los ntawm cov txheej txheem me me, thiab tom qab ntawd lub microscopic txheej txheem yooj yim puas yooj yim los ntawm sab nraud rog. Tus qauv txheej txheem no muab cov ntsiab lus txheej txheem zoo thiab cov yas, ua rau nws yooj yim rau kev txiav thiab cov tawv nqaij, thiab nws lub hardness tau qis dua pob zeb diamond.

 

Los ntawm graphite mus rau pob zeb diamond: qhov txuj ci tseem ceeb ntawm cov khoom siv dag zog

Muab qhov sib txawv loj ntawm pob zeb diamond thiab graphite, cov kws tshawb fawb tau ntev tau cog lus los tshawb nrhiav txoj hauv kev los tsim cov pob zeb diamond los ntawm graphite. Los ntawm Moissan lub siab kub hluav taws xob rauv sim, mus rau tom qab tawg txoj kev, vapor deposition txoj kev, thiab tom qab ntawd mus rau niaj hnub high-temperature thiab high-pressure txoj kev, txhua technologies innovation marks lub deepening ntawm tib neeg kev nkag siab ntawm carbon cov ntaub ntawv thiab kev txhim kho kev. peev xwm. Tshwj xeeb tshaj yog cov vapor deposition txoj kev thiab cov high-temperature thiab high-pressure txoj kev, lub qub yuav loj hlob pob zeb diamond films los yog crystals ntawm ib tug tshwj xeeb substrate los ntawm precisely tswj lub deposition txheej txheem ntawm carbon atoms; tom kawg siv cov nyhuv catalytic ntawm cov catalysts nyob rau hauv qhov kub thiab txias siab los hloov graphite rau hauv cov khoom loj ntawm pob zeb diamond, uas yog siv rau hauv cov cuab yeej txiav thiab cov hniav nyiaj hniav kub.

 

Anomaly ntawm hardness thiab melting point: vim li cas lub pob zeb diamond muaj qhov tsawg melting point?

Los ntawm qhov kev xav ntawm microscopic, melting txhais tau hais tias cov khoom uas ua rau cov khoom tau txais kev ywj pheej nyob rau hauv peb-dimensional qhov chaw thiab tuaj yeem ntws dawb. Rau pob zeb diamond thiab graphite, qhov kev ywj pheej no yuav tsum muaj kev puas tsuaj ib txhij ntawm ntau cov nyiaj sib cog lus, yog li lawv cov ntsiab lus melting siab heev.

 

Rau feem ntau muaju, qhov siab dua lub hardness, siab dua lub zog melting. Txawm li cas los xij, nyob rau hauv rooj plaub ntawm pob zeb diamond thiab graphite, lub hardness thiab melting point yog inconsisistent.

 

Txawm hais tias lub pob zeb diamond tau paub txog nws cov khoom siv tsis sib haum, nws qhov taw tes melting yog qhov poob nthav qis dua li ntawm graphite. Qhov laj thawj tom qab qhov no yog cuam tshuam nrog lawv lub rooj sib tham sib xyaw ua kom muaj zog thiab cov qauv teeb tsa. Cov pa roj carbon atoms hauv pob zeb diamond siv SP3 hybridization, thiab lub sib haumaly des tsim tau ntev dua (}. 155nm) thiab lub zog sib khi yog tsawg; Thaum cov pa roj carbon atoms hauv graphite Siv SP2 hybridization, qhov kev sib khi lus ntev yog luv ({4}}. 142nm) thiab lub zog sib cog lus siab dua. Yog li ntawd, thaum ob qho tib si hloov los ntawm cov khoom siv mus ua kua, txawm tias muaj lub zog sib cav sib haum, ua rau muaj zog sib cav rau graphite dua rau pob zeb diamond (3680 degree rau graphite thiab 3550 degree rau pob zeb diamond).

 

Thermal conductivity ntawm graphite thiab pob zeb diamond

Graphite yog cov khoom siv thermal conductivity zoo heev, thiab nws cov thermal conductivity yog ntau dua li ntau cov khoom siv. Cov thermal conductivity ntau ntawm graphite feem ntau yog siab, tab sis tus nqi tshwj xeeb txawv nyob ntawm qhov zoo ntawm cov graphite thiab cov kev xeem.

 

Cov txheej txheej txheej ntawm graphite yog tus yuam sij rau nws cov thermal conductivity. Cov pa roj carbon atoms nyob rau hauv cov khaubncaws sab nraud povtseg yog nruj nreem khi los ntawm cov muaj zog covalent bonds los tsim ib tug ruaj khov qauv, uas yog conducive mus rau lub ceev ceev ntawm tshav kub. Txawm li cas los xij, vim hais tias cov khaubncaws sab nraud povtseg txuas nrog lub zog van der Waals tsis muaj zog, thermal conductivity ntawm graphite nyob rau hauv cov kev taw qhia interlayer kuj tsis muaj zog. Txawm li cas los xij, graphite tseem siv dav los ua cov khoom siv thermal tswj hauv qhov chaw kub kub, xws li cov dab dej kub, thermal conductive films, thiab lwm yam.

 

Rau pob zeb diamond, txawm hais tias pob zeb diamond yog ib qho insulator thiab tsis muaj cov hluav taws xob dawb, nws muaj qhov zoo tshaj plaws thermal conductivity ntawm tag nrho cov khib nyiab. Nws thermal conductivity qeb ntawm qhov zoo tshaj plaws hauv cov xwm. Nyob rau hauv chav tsev kub, lub thermal conductivity ntawm pob zeb diamond tuaj yeem ncav cuag 2000 ~ 2200 W / (m·K), uas yog 4 ~ 5 npaug ntawm tooj liab thiab nyiaj, 4 npaug ntawm silicon carbide (SiC), 13 npaug ntawm silicon ( Si), thiab 43 npaug ntawm gallium arsenide (GaAs). Tsis tas li ntawd, cov thermal conductivity ntawm hom IIa pob zeb diamond ntawm cov kua nitrogen kub tuaj yeem ncav cuag 25 npaug ntawm cov tooj liab, uas qhia cov thermal conductivity. Pob zeb diamond muaj cov tshuaj ruaj khov, tiv taus cov kua qaub thiab alkalis, thiab tsis hnov ​​​​mob nrog qee yam tshuaj ntawm qhov kub thiab txias. Cov khoom no ua rau nws tswj tau zoo thermal conductivity txawm nyob rau hauv qhov chaw huab cua.

 

Tsis muaj neeg siv hluav taws xob dawb hauv pob zeb diamond qauv, yog li cas nws tuaj yeem muaj thermal conductivity? Nws hloov tawm tias cov essence ntawm thermal conductivity thiab hluav taws xob conductivity yog qhov sib txawv, uas yog qhov tseem ceeb ntawm cov cua sov yog qhov kev txav ntawm cov khoom. Yog tias tus nqi txav ntawm lub tshuab tsom me me yog nrawm, cov khoom siv sab nraud yog qhov kub thiab txias. Qhov kev txav ntawm lub tshuab tsom me me tuaj yeem pub dawb thiab tsis xwm yeem, lossis nws tuaj yeem yog kev co tus kheej ntawm lub ntxaij. Nws tuaj yeem xav tias qhov kev ua haujlwm hnyav tshaj plaws ntawm pob zeb diamond tau tiav los ntawm kev co los ntawm cov pa roj carbon atoms lawv tus kheej ntawm lub ntxaij. Vim yog qhov kev txiav txim siab ntawm lub pob zeb diamond heev, thiab qhov tseeb tias nws yuav tsum muaj cov pa roj hluav taws xob tau yooj yim ua rau kev rov ua haujlwm hauv lub lead ua, yog li nrawm Ua cov cua sov los ntawm ib qho chaw mus rau lwm qhov, ua pob zeb diamond cov khoom siv nrog qhov zoo tshaj thermal conductivity.

 

Qhov tshwj xeeb thermal conductivity no ua rau pob zeb diamond dav siv nyob rau hauv high-tech teb. Piv txwv li, nyob rau hauv semiconductor nti ntim, pob zeb diamond tuaj yeem ua cua sov sai los tiv thaiv cov nti los ntawm kev ua haujlwm tsis zoo lossis txo kev ntseeg siab vim qhov kub thiab txias. Tsis tas li ntawd, pob zeb diamond tseem siv los tsim cov dab dej kub thiab cov khoom siv thermal conductivity rau cov khoom siv hluav taws xob siab. Vim nws cov thermal conductivity siab thiab qis thermal expansion coefficient, nws tuaj yeem txo qhov kev hloov pauv ntawm cov khoom thaum kub hloov, thiab txhim kho kev ruaj ntseg thiab kev ntseeg siab ntawm cov khoom siv.

Raws li cov roj carbon, pob zeb diamond thiab graphite qhia tag nrho cov thaj av zoo ntawm lawv cov teeb meem micrigntures sib txawv. Los ntawm lawv cov kev sib nrig sib pauv mus rau lub cev nqaij daim tawv, txhua qhov kev tshwm sim ntawm kev tsis paub txog kev thiab cov lus tim khawv rau tib neeg kev txawj ntse thiab kev nce qib.