TAP CHI HOA HOC
DOI: 10.15625/0866-7144.2015-00166
53(4)480^84 THANG 8 NAM 2015
T 6 N G Hap VAT LIEU B A N G PHU'aNG PHAP P H A N CFNG N 6 VA
TINH C H A T CUA LaP04:Eu KJCH THU-aC NANOMET
Ngayen Vu'*, Ph^m Birc Roan^, T9 Minh Th^ng^, Tran Thi Kim C h i \ Man Hoai Nam', Nguyen Thi Thanh'
' Vi0n Khoa hgc Vdt li$ii, Vi^n Hdn ldm Khoa hgc vd Cong ngh? Vi§t Nam
^Khoa Hoa hgc, Tru&ng Dgi hgc Suphgm Hd Ngi
^Tru&ng Cao ddng Die^c Phu Thg Din Tda sogn 05-01-2015; Chap nhgn ddng 26-8-2015
Abstract
Eu (III)-doped LaP04 nanophospbors were prepared via combustion synthesis using urea as fuel and metal nitrales as precursor. Structures, morphologies, and pbotoluminesceDt properties of tbe LaP04:Eu were sUidied by X-ray diffiaction, scarming electron microscopy, photoluminescent and excitation pbotoluminescent spectra. The av»age diameters for tbe phosphor particles are 5-20 nm. Tbe effects of Eu(Ill) doping process and beating temperature 00 stmcture and optical properties of nanophospbors have been mvestigated. LaP04:Eu pbosfdiors show tbe intense peak at 594 nm corresponding to the ^DQ-'FI transition of Eu (III) in inversion symmetry sites.
Keywords. LaP04:Eu, combustion synthesis, nanomaterials, nanophospbors, luminescent.
I.Gl6lTHI$U
Vgt lifu nano phat quang dang la vdn dl dugc gidi khoa hgc fren thi gidi quan tam do cd rdt nhieu djnh hudng iing dyng thye t l . Viec chl tgo va nghien ciiu tinh chdt quang cua vat lieu nano nen LaP04, pha tgp cac ion ddt hiem nhu Eu(III), Tb(in), Ce(UI), Sm(III), Er<I!I), ... dang thu hiit nhieu nha khoa hgc frong vd ngodi nude frong vifc tdng hgp, nghien cthi tinh chat va khd ndng ung dyng. Vifc thay ddi ion pha tgp, none dg pha tgp nhdm muc dich nhgn dugc cdc tinh chat quang mong mudn nhu hifu suat phat quang, mdu phdt xa [1-9]. Vgt lifu LaP04 pha tgp ion ddt hiem nhu Eu(III) (ky bifu, LaP04:Eu) cho phat xg mdu dd cam vdi phdt xa frgi ung chuyin mirc ^Do - ^Fi ciia ion Eu(III) d khoang 583-595 nm do vgt lifu cd tdm ddi xiing dao [1-6].
Vifc tong hgp vd nghien cuu tinh chdt quang cua vgt lifu LaP04:Eu hifn con la ddi tugng nghien ciiu hap ddn. Ngudi ta da su dyng nhieu phuang phdp khac nhau nhdm chl tgo dugc cac vgt lifu nay, frong dd cd cac phuang phdp: tdng hgp trong dung mdi nhift dg sdi cao, thiiy nhift, sol-gel, phuong phdp phan iing pha rdn.... de chl tgo vat lifu LaP04:Eu.
Cho din nay, tren the gidi chua cd nhifu cdng trinh nghien cihi che tgo vgt lifu nln LaP04bdng phuong phap phan iing no [10-12]. Vifc tdng hgp vat lifu nano phat quang YV04:Eu vd YV04:Er,Yb dd dugc
tifn hanh bdng phuang phap ^ihan ung nd [13-15].
Bai bdo nay trinh bay kft qua tdng hgp vat lieu LaP04:xyoEu (x = 1-9) bdng phuong phap phan iing nd, su dyng tien chat la mudi nitrat ciia kim logi va ure Iam nhien lifu cho phdn irng oxi hda - khii. Anh hudng cua nong dg pha tap (dugc dinh nghui la ti If % mol ciia ion pha tap Eu so vdi tdng lugng ioo kim loai) den tinh chdt quang ciia vat lieu dime khao sdt, ngoai ra dnh hudng ciia nhift do nung mui khoang tir 500 den 900 °C d l tim ra nhiet dg nung tdi uu cho qua frinh hinh thanh vat lieu cung dugc nghien ciiu.
2. THI/C NGHIEM
Vdt lifu LaP04:Eu dugc chl tao bdng phuang phap phan ling nd (theo quy frinh nhu md td frtmg hinh 1) tii cac tiln chdt la La(N03)3, EuOSfOj)^ NHj, H3PO4, vd ure lam nhien lieu cho phan iing oxi hda - khii. Vdt lifu LaP04:5%Eu dugc nung d cac nhift tlf khac nhau tu 500-900 "C frong 1 gicr, cac miu co ndng dg pha tgp thay ddi LaP04:x%Eu (x = 1,3,5,7, 9) ciing dugc nung d 900 "C trong 1 gid.
Gian do nhilu xa tia X (XRD) cua cac mdu dugc ghi fren may Siemens D5000, biic xg CuK^ tgi Vifn Khoa hgc Vgt lifu. Anh hiin vi difn tii qu^ (SEM) dugc thye hifn fren hf S4800 (Hitachi) tai Vien Vf sinh Dich te Trung uong. Phd huynh quang dugc do
TCHH, 53(4), 2015
fren hf do huynh quang phan gidi cao iHR550 tgi phdng thi nghifm trgng dilm Vifn Khoa hgc Vgt lifu: su dung ngudn kich thich bdng lade 266 nra.
H:
[ HjPOj I
Pp
Hinh 1: Quy frinh t6ng hgp vgt lifu LaPOiiEu
3. KET QUA VA T H A O LUAN
Gidn dd nhieu xg tia X (XRD) va dnh hiin yi difn tii quet (SEM) dugc sii dyng dl nghien ciiu cau tnic
Nguyin Vuvdcgngsu vd hinh thai hgc cua vgt lifu tong hgp dugc.
Hinh 2 la gidn do XRD ciia vgt lieu LaP04:5%Eu nung d cac nhift dd khac nhau frong khoang 500-900 °C. Kit qua cho thdy vat lifu cd cdu true tinh the tdt, khd phii hgp vdi cac ket qua do cdng bd ve cau tnic vat lifu LaP04. Gidn dd cho thdy cdc dinh nhieu xg ciia vat lieu nung d cac nhift dg khac nhau diu phii hgp vdi the chuan JCPDS 32-0493 ciia LaP04 va khdng cd sy xudt hifn ciia cdc dinh nhieu xg Ig dugc quan sat. Dieu dd chiing td cac vat lieu thu dugc la don pha va the hifn cdu tnic ciia mgng nen LaP04. Dg rgng ciia vgch nhieu xg cd gidm xudng khi tdng nhift dg nung nhung khdng thye sy ro rft. Dya vac dg md rgng ciia vgch nhieu xg tia X, kich thudc tinh the dugc tinh todn dya theo cdng thirc Schen-er: D = (0,89>.)/(pcose), vdi D Id kich thudc trung binh ciia tinh the, X la budc sdng ciia tia X (nguon tia X d ddy la CuKa, X = 0,1541 nra), p va 0 tuang img la dg ban rgng ciia vach nhieu xg vd gdc nhieu xg dugc sir dung frong phep phdn tich. Kit qua cho thdy, kich thudc trung binh ciia cac radu LaP04:5%Eu nung d 500, 600, 700, 800 vd 900 T tuong ling Id 5,4, 6,2, 6,4, 7,6 va 7,7 nm. Nhu vgy, khi tang nhift dg nung vgt lifu kich thudc hgt cd tang len nhimg khdng dang kl. Cac ket qua viia neu cho thdy frong khoang nhift dg nung tii 500 den 900
°C khdng cd sy chuyin pha. Dilu nay cd the do ndng lugng nhift ben ngoai biln ddi frong khodng nhift dd ndy cbua dii gdy ra nhftng bien ddi Idn.
M(«9)
Hmh 2: Gian do nhilu x? tia X cua LaP04:Eu nung 6 cac nhi?t dp khac nhau:
500 (a), 600 (b), 700 (c), 800 (d) va 900 °C (e); v?ch thing dung la the chuan 32-0493 ciia LaPO, Hinh 3 trinh bay cac anh SEM tieu bieu ciia vat dfing dSu v i chii ySu cr dudi 20 nm. Ket qua nay li^u LaP04-5% Eu dupc nung 6 cac nhiet dp khac ciing phii hpp vdi ket qua thu dupc tit gian do XRD
nhau(500,700va900°C)trong 1 gid. AnhSEM, cuavatlieu. _ _ , cho <hiv hat vat lieu CO dang Ura cau, kich thuoc kha Huynh quang cua vjt li?u LaP0,:5%Eu do o
TCHH, 53(4), 2015
nhiet dp phong, kich thich bang lade dupc trmli bay tren hinh 4.
Tong hop vdt liSu bdni
Hmh 3: Anh SEM ciia cac mlu LaPO,: 5 % Eu nung o 500 (trai), 700 (giiJa) va 900 °C (phai)
1,0-
0,5 aPO, Eu'*(5 /o)
' D , - ' F ,
s
'a 'F
1'^
W
X
• \ ' °
1 ' D , - ' F J
viU
TXC" 266 nm
. • ' • ^
ij \
Hinh 5 frinh bay phd huynh quang ciia vat lifu LaP04:5%Eu dugc nung d cac nhift do khac nhau, mau dugc kich thich d budc sdng 266 nm va dirge gift nguyen cdc dieu kifn do (de so sdnh dugc). Pho huynh quang ghi n h ^ dugc cd dgng tuang ty nhau (vi fri va ti If cudng dg cdc vgch phd), cudng df huynh quang tang nhg theo nhiet dg nung mdu cd thf lien quan tdi sy hoan thifn hon cdu true tinh the.
550 600 650 700 BUdc s6ng (nm)
Hinh 4: Phi huynh quang ciia LaP04:Eu (5 %), kich thich d 266 nm
Pho huynh quang gdm cac vgch h?p tuong iing vdi cac chuyin ddi 'DQ - 'FJ (J = 0, I, 2, 3, 4) cua ion Eu. Cac dinh tifu bilu la 579 nm (^DQ - 'FQ) ; 588, 592, 594 nm (*Do - ' F , ) ; 612, 621 nm (^Do -
%) ; 650 nm (*Do - ^Fj); 685, 697 nm (^DQ - ^F4).
Vl huynh quang cua Eu''*, chuyen ddi 'DO - ' F I la chuyen ddi ludng cyc tir dugc phep vd cudng dg cua nd phy thugc vao mdi frudng chung quanh cua ion Eu(lll); chuyen ddi 'Do - ^Fi la chuyin ddi luang cyc difn dugc phep va cudng dg cua nd nhgy vdi cdu friic djnh xir ciia ion Eu(IlI); chuyen ddi *Do -
^Fo la chuyin ddi bj cdm vd dugc gidi phdng mdt phdn tiiy theo doi xutig cua tinh the, chuyen ddi nay chi nhgn dugc khi ion Eu(III) dugc dgt vao vi tri doi xirng thap. Do dd, ion Eu(lII) dugc sii dyng lam dau do cdu true de xac djnh moi trudng djnh xir frong tinh thi [7]. Theo ket qud chl ra tren hinh 4, cudng dg huynh quang img vdi chuyen ddi *Do - 'FQ la rat yeu, ehirng td LaP04 cd tinh ddi xiing cao. Phat xg ling vdi chuyen ddi 'DQ - 'FJ trgi ban so vdi cac phat xa irng vdi cac chuyen ddi khac Id do frong vdt lifu LaP04 cd tdm ddi xiing dao. Phd huynh quang ma chung tdi ghi nhgn dugc phii hgp vdi cac cac cong frinh dd cdngbd [1-3, 5, 7].
2 6000
540 560 580 600 620 640 660 680 700 720 Budc s6ng (nm)
Hmh 5: Phd huynh quang ciia LaP04:Eu (5 %) theo nhift dg nung mau tii 500 den 900 "C De kilm tra dnh hudng cua ndng dp Eu(III) len tinh chdt phdt quang, Eu(III) da dugc pha vao mgng nln LaP04vdi cdc ndng dd khde nhau. Hinh 6 va 7 trinh bay pho huynh quang ciia LaP04:Eu vdi cac ndng dg Eu trong khoang 1-9 %. Cd thi nhan thay, cudng dg huynh thay ddi khdng dang kl khi ndng df Eu(III) tang (hinh 6). Tir phd huynh quang cho th^y vdi nong dg 5 % chua thi hifn sy dap tat huynh quang do CO chl truyin cgng hudng gifta cdc ion Idm tieu tan nang lugng kich thich. Trong vat lifu khoi, sy dap tdt nong dg dd xay ra vdi mirc pha tap tren.
Tuy nhien, ti If cudng dg phdt xa iing vdi chuyen ddi *Do - ' F ; SO vdi cudng dg tuong iing vdi chiqwi ddi 'DO - ^F[ tdng khi tang ndng dg pha tgp Eu (II!)
T C H H , 53(4), 2 0 1 5
(hinh 7). Dieu nay c d t h i d o khi l u g n g Eu(III) frong vat lifu tdng, tinh ddi x i m g ciia tinh t h i mgng chu LaP04 gidm ( d o s y sai k h a c v l b a n kinh ion ciia E u ( n i ) v a L a ( l l l ) ) , dan d i n phat xg frdi c u a c h u y i n ddi l u 5 n g c y c tir *Do - ' F I frong vat lifu cd t a m doi xiing dao g i a m vd tang d^n phdt xg d o c h u y i n ddi ludng c y c difn ' D Q - ' F j d g c frung clio vat lifu khdng cd tdm ddi xirng ddo.
600 650 Budc s6ng (nm)
Hmh 6: P h o h u y n h q u a n g c u a L a P 0 4 : x % E u ( x = 3 , 5 , 7 , 9 )
Hinh 7: Phd h u y n h q u a n g da d u g c chudn hda ciia L a P 0 4 : x % E u (x = 1, 3 , 5, 7, 9) trong k h o a n g
5 5 0 - 6 4 0 n m 4. K E T L U A N
Vgt lifu L a P 0 4 : 5 % E u da d u g c c h l tgo thanh cong bdng p h u o n g p h a p p h a n iing nd. V g t lifu thu dugc Id dim pha va k h d n g ghi nhgn d u g c s y xudt hifn ciia c a c p h a tgp c h a t . S y p h a tgp v a thay dpi nhift dg n u n g mdu k h d n g gay n h i l u a n h h u d n g d i n cau friic, hinh thai ciia vgt lifu, s y tdng nhift dg n u n g tu 500-900 "C k h d n g xdy ra s y thay ddi Idn ndo v e kich t h u d c hgt. Phd h u y n h q u a n g ciia vgt lifu LaP04-Eu d e u t h i hifn cdc c h u y i n d d i phat xg dgc frimg ('Do - ' F j , J = 0 - 4 ) c u a E u ( n i ) . P h o huynh
Nguyin Vu vd cgng su q u a n g c u a vgt lifu L a P 0 4 : E u thay ddi khdng ddng k l khi tdng n o n g d o E u pha tgp h o | c thay ddi nhiet dg n u n g m a u t u 5 0 0 - 9 0 0 °C.
L d i c a m o n . Kinh phi thiec hiin dirge tdi trg tir di tai ca sa cdp Vi?n Khoa hgc Vgt li^u. Kit qud dirge thuc hiin tgi Phong tht nghiim trgng diim vi vgt li4u vd linh ki^n dien tu, Vien Khoa hgc vdt li^u, Vi?n Hdn ldm Khoa hgc vd Cong ngh? Viet Nam.
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•: Nguyen Vu Vifn Khoa hgc Vdt lieu
Vifn Han Iam Khoa hgc va Cdng nghf Vift Nam So I8,HoangQudc Vift, Cau Giay, HaNgi E-mail: [email protected].
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