NHlN Rfl TH€ GI6I
TONG HOP MANG MONG
DUNG CHO CAC L 6 P PHU THONG MINH
NhOng ldp p h i thSng minh co kh^ njng thay dfi'i tfnh chat quang hpc theo nhift dfi difa trfin nfi^n t i n g oxid vanadium (VO^) hi^n dang dirgic xem la mfit trong nhOng phifong phap hifiu qud d ^ difi'u chinh nhifit dfi trong cac toa cao fi'c, nhd do gidm thilu nhu cfi'u sUf dvng nang liT^ng va fi n h i l m dfi thj. Tuy nhifin, nhOng han chfi'vfi' nhifit dfi thay doi linh chat quang hpc cua mang m6ng VO^ cung nhir gia thanh cao cAa cac phirong phap Jieu chfi' khifi'n cho vfit iifiu nay v i n chira dUffc ufng dpng rfing rai trong thpc tfi'. Gan lay, phirong phap magnetron sputtering da dirpc sur dpng d l difi'u chfi'thanh cfing mang 'Ti6ng VO doping W vdi gia thanh rd, ddc bifit co t h i khdc phpc dPpc nhifng han chfi' Wn CO cua oxid nay, nhd do hda hpn mfit khd n^ng dng dung da'y t r i l n vong.
udng nhiet trong dA dll
;e tu nhUng nam cull cCia the ky XX, hlSn tupng tang nhiet dp trong cac dd thj ldn cdn dUdc bilt 1 tSn gpi "Oc die nhiet", da dUdc d l cap den rat iu trong cac bao cao v l mdi trudng va khi hau toan
[1,2]. Vdi sU phat trien khdng ngUng ciia cac tda cao ting, di kem vdi viec giam thilu dien tich cay h xung quanh khiln cho mai nha hogc tudng cua cao Ic nay trd thanh doi tupng hap thu nhiet mgnh Uc xg mat trdi. BSn cgnh dd, ciia so kinh la mpt g nhOng thiet k l truyin thing d cac tda nha Idn, phep con ngUdi cd the nhan biet ngay va dSm, g nhu canh quan ben ngoai tU bSn trong tda nha.
nhien, cung vdl mai va tudng, cCfa so kinh la mdt g nhUng ndi hip thu anh sang va trao doi nhiSt iu nha't vdi bUc xg mat trdi. Nhiet dd tgi cac be mat
xiic nay cd t h i tSng hdn lO'C [3], dan din sp gia ] mgnh me nhu ciu sCr dung cac thilt bj lam mat
trong tda nha, kit qua la lupng dien nang tiSu thp
;U d nhilm mdi trudng dd thj ngSy mdt gia tang.
)a CO nhilu ky thuat dua tren vat liSu nano dupc ighj de gill quylt vin de nay. Mdt trong nhflng ong phap hiSu qua IS sfl dung bdt mau phin xg g ngogi de sdn phii tudng, hogc cac Idp mang ig phan xg hing ngogi dung trong cCla so kinh [4].
1 chat Chung cCia cac vgt liSu nay IS khi nang phin ignh anh sang mat trdi, trong dd, phan xg chii y l u 'bUc xg nam trong viing hing ngogi (hon 50% bflc I mat trdi) tu dd tgd ra cac b l mgt cd nhiSt dd thip.
en gpi thdng thudng la cac Idp phCi each nhiet hay
Hinh i: biSu d6 minh hca hi§n IU0ng X)c dSio nhi§t" - nhiet do trong cac khu do IN luon tSng cao hon so vdi cac hhu vile
ndng thdn nhiSu ciy cdi
vat lieu lam mat, chung dupc Ung diing rdng rai tren cac be mat ben ngoai cac tda nha ldn, giam thieu hlSu qua cac qua trlnh truyin nhiSt tfl mat trdi vao bSn trong nha.
Tuy nhien, nlu nhu vao mCia hS, cac vat lieu nay cd t h i giim nhiSt dp tU nhien bSn trong cac tda nha, thi vao mua ddng, chung Igi gay ra cac van de Idn dd'i vdi nhu ciu sudi Im. Viec ptikn xg hieu qua bflc xa hong ngoai khiln cho nhu cau sfl dung cac thiet bj dien d l sudi Im trong mua ddng tang cao, khien tiSu ton nang iupng va gay ra cac van d l d nhilm mdi trudng.
VI vay, de CO the son len tudng cac cao oc hay Ung dung trong kinh cfla so d nhflng thanh pho cd khi hau biln dll theo mua, cac vat liSu phii hay bdt mau khong chi phai phkn xa tot anli sang mat trdi (vao mua he) ma cdn phll cd khS nang cho bflc xg mat trdi truyen qua khi cin thilt (vac mua ddng). Ndi each khac, phat
„ . . „ H09tdona c.
So thang 7.2012 j Q j o A H O C "
NHlN Rfl TH^' GI6I
Mua hS Mua <JOng
•< •
Hinh 2 lop phu Ihdng minh cd kha niing pbAn xn tit bQc X9 m$l trdi vdo miia hd {nhidt dd cao) vd din truydn M c xa mdtIrdi vdo mda ddng (nhidt dd thdp) triln vat liSu mang phii thing minh cd t h i thay dli cac tinh chit quang hpc theo nhi$t dd bSn ngoai la m|t muc tJSu quan trpng va nhilu tilm nang flng dung dli vdi cac nha khca hpc hl0n nay.
Mang mong thong minh dua tr6n VO,
HiSn tupng thay doi tinh chit quang hpc theo nhiSt dd thudng dupc tim thiy d mdt s l oxid kim logi ho$c sulfure kim logi (5,6]. GiOa cac hpp chit dd, VO, dupc bilt den nhu mdt vat lieu cd tinh chat quang hpc biln dli hieu q u i tlieo nhiSt dd nhd vao qua trinh djch chuyin pha thuan nghjch rat dac trUng [7]. 6 nhiet dd dudi 68°C [7], VOj cd clu true tinh t h i don ta, la mpt hpp chit ban din va cd dp truyin qua cao, Khi nhiSt dp VUpt qua 68°C, chl trpng vdng vai pico giSy, VO^ se ngay lap tflc chuyin sang clu trUc tfl phUdng, cd tinh chit ciia kim logi va dp phkn xg anh sang cao [8,9],
Htnh 3: hai cSu tnic tinh IhS cOa VO^. (a) CSu true llnh thS ddn Id cua VO^, (bj CSu tnic linh thStddidn ciia VO^
Mdt dgc dilm qugn trpng khac cCia VO^ la su biln del tinh chit quang hpc theo nhiSt dp chl ap dgng hieu q u i cho anh sang cd budc sdng nam trong vurig hong ngogi [10], vung anh sang sinh nhl§t nhilu nhit tfl bUc xg mat trdi. Dli vdi cgc bflc xg cd budc sdng nam trong vung khS kiln, qua trlnh chuyin pha khing Jnh hudng nhilu dS'n dp truyin qua. VI vay, VO, khdng cht hpan tpan cd the dupc flng dgng trong son phi ISn tudng
cOa cac tda nha mS mang mdng ciia oxid nay co dupc xem la vit li$u ly tudng d l p h i ISn trSn cac cj s l bing kinh d cao van phdng cac Ic.
Tuy nhiSn, nhi^t d | eifiC vin cdn kha cao so it ckc biln d l l nhl|t d | khdng khi bSn ngoai do m|tffi gay ra. D$c bi^t, dudng cong t r i nhl$t (thi hi^n mi) d | chSnh l$ch nhi^t d | cua qua trlnh chuyin pha j tang va giim nhi^t di) cfla VO, cdn tUdng dli j Dilu nay s§ giim mflc d | thuan nghjch cfla qua ti chuyin pha. Hai tinh chit nay da gidi hgn khj nl flng dung cflg VO, vad thflc t l , khiln cho oxid nayi din ngy oh? mdi dupc nghiSn cUu chu y l u trong phi thlnghi|m[11].
Tdng hon mang mdng HO, doping W
Nhflng nghiSn eflu gin dSy cho thiy, qua doping cac ion kim logi chuyin tilp nhu W**, Mo**, f#, F- hay Cr^* vao mang mdng VO, cd t h i giim nhi' chuyin pha cua VO, m|t each hi§u q u i [12,13,1' 0$c bi$t, khi doping ion W, nhiSt dd chuyin pi t h i hg xuIng g i n bing nhi$t d | plidng [16]. N dilm ciia phUdng phap nay la vi^c doping cac loi mang mdng VO, se hlnh thanh cac mflc nang \\ifi, vCing trong c l u true diln tCf, ndi mS eac electronii t h i hip thu ning lupng thip (vung hing ngogi) vit kich thich ISn vung d i n . Khi dd d nhiSI d | thip In nhiSt dd chuyin pha (vap mua dSng), d | truyin qt ciia anh sang se bj giim dc mdt phin anh sang dii hip thu, tfl dd lam giim khi nang truyin nhi^tquavl li$u [17],
Ngoai ra, hiu hit cac nghiSn eflu eho din nayt t$p trung vko ting hpp mang mdng VO, cd dopm!
bing cac phUdng phap dit tiln trong phdng thInM [18,19]. Trong m|t nghiSn eflu g i n dSy, Shengij va cac ding nghidp [20] d i n tfl Trudng Dgi hpcH hpc va Ky thu^t Thupng Hii da ting hpp thinh tl mang mdng VO, doping W bing ky thu$t "magneH sputtering" d nhi$t d | phdng vdi chi phi thip hoi nhiSu so vdl cac ky thu$t trudc day.
Blu tiSn, chit nin thCiy tinh se dupc Iln lifli sgch trong acetone, ethanol, nudc c i t va lim!
bang khi nito. Sau dd, chit n i n se dupc dat vkatu magnetron sputtering mit chilu da trang bi sin kim logi chfla 1,4% W va 98,6% V. Dudi dimg Argon 80 seem, ddng di^n mdt chilu cudng do A va hi^u diSn t h i 400 V, cac idp kim logi se iSm dupc hda hol va k i t t i a ISn chSt,- jn thOy tinhiS suot qua trlnh k i t tCia, buIng ph ,,-, uno dUdcB djhh 6 nhiet dp phdng. Culi cflng, mang mdnglfl nay se dupc nung trcng khi quyln j ^ ^ , ^ „ j j
88 K H " O A H O C S « * - 9 ^ - = ° ^ ^
NHlN RR TH6 GI6I
4 gici de hinh thanh mang m6ng VO^ doping W.
Tinh chat quang hoc cua mang mong VO,
dopmgW '
Sau khi tdng hop, cac tfnh ch^t quang hgc cCia .rn^ng m6ng VO^ doping W l^n lUdt dUdc kiSm tra theo nhidt do va so sanh vdi m^ng m6ng VO^ kh6ng doping ,[21]. Hinh 4 cho thay khac vdi m§u VO^ kh6ng doping -CO nhi§t dd chuyin pha trong khoSng 70°C, quk trlnh
^doping W vao cS'u true VOg da l^m gikm nhi^t 66 jChuyIn pha xu6ng c6n khoSng 40°C. Bi^u n^y c6 t h i
^Udc giii thfch nhd vao si^ thay ddi c^u trCic tinh t h i hpc cCia VOj. Trong c^u triic pha tinh th^ ddn tk cCia VOg, lien kdt V^-V^' da^c hinh thanh bdi c^c ion V sSp
<ep dgc trgc c [22,23]. Khi d6 VOj c6 tinh ch^t nha m6t
^h^t ban d§n. Nhang khi ion W du^c doping vao c^c v\
;ua ion V, lien kdt V^-V** bj b^ gay, hinh thanh ckc I lien kdt V^^-W^* va V^'-V** bdi ckc electron thudc in Idp d cCia ion W [24,25]. Vdi sy thay ddi nay, c^u
; pha ddn ta khong con ben vQng nQa, dkn den viec n nhidt dd chuyin pha cDa mang mdng VO^.
chd nay khdng chf dem l^i nhidu Igi [ch kinh t l nhd gia th^nh rd, mk cdn tdng hdp thanh cdng vat lieu mang mdng VO^ c6 nhi^t dd chuyin pha th^p va dd truydn qua cao, haa h?n ufng dyng cho nhQng Idp phu tidm nSng trong thi;c td •
LTK (tdng hop)
Pure V O i film
: " « • » > •
W - V ctf-tputtercd nim
• Heatine K Coollnc B Hcaiinx
T e m p e r a t u r e ( X : )
nh 4: dudng cong biSn dSi rf$ truySn qua theo nhi§t d0 cda ing mdng VO^ tinh khiit (pure VO^ film) v^ mdng mdng VO^
doping W (W-V co-sputtered film)
Hinh 4 cung phSn anh mQc do truyen qua cua ^nh ig ddi vdi cac mau kh^o sat. trdn nhidt dd chuyen I {70"C ddi vdi mang mdng VO^ tinh khiet va 40°C vdi m^ng mdng VO^ doping W) do truydn qua cCia i l u deu la khoSng 13%. NgUdc lai, dadi nhidt do lyln pha, do truyen qua cua miu VO^ tinh khid't la 6 trong khi dd truyen qua ci!ia mlu VO^ doping W la i. Kdt guk niy cho thdy khi doping W bang phadng
!p magneton sputtering, do truydn qua cCia VO^ h^u f chtbj g\km nh? [21]. NhU vay, phUdng phap dieu
Tai Mou tham khao
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Sothang 7.2012 [ ^ j j O A H O C
