TAP CHI KHOA HOC - DAI HQC DONG NAI, SO 04 - 2017 ISSN 2354-1482 S\f TAO PHA VA TINH CHAT CHUYEN PHA N H O E CUA H E V A T LIEU K H O N G CHlTA CHI (1 - x)BCT - xBZT
TS. Dgng Ank Tudn^
PGS. TS. Vo Tkank Tun^
TS. Trwang Vdn Chwang^
ThS. Nguyin Tki Quynh Liin*
TOM TAT
Bdi bdo Pink bdy mgt sd kit qud nghiin cuu vi cdu true vd tinh chdt chimin pha nhde cua he vdt lieu BZT - BCT. Theo do, khi tdng ty phdn BZT tiong h$, cdu true tinh thi, hdng sd mgng cua vdt lieu thay doi. Hoi ddp diin mdi - nhiit do phdn dnh dgc trung chuyen pha nhde ciia vdt lieu.
Tir khoa: BZT - BCT, chuyin pha nhde, khong chi
1. Gidi thifiu [5], [6]. Cac ket qua nay cho phep Nam 2009, Liu vd Ren da xdy dyng chung ta hy vgng vfi khd nang chfi tao dupc he vat lieu dp difin khdng chi cdc vgt ligu khdng chda chi cd tinh dp BaZro,2Tio,803-;cBao,7Cao,3Ti03 cd he sd difin mgnh so vdi cdc vdt lifiu chda chi.
dp difin d33 dat 620 pC/N khi x ^ 0,5, Trong cdc nghifin cdu dupc de cdp, cac cao han cd gid tri thu dupc ttfin PZT - tham sd cdng nghfi che tao vat lieu la 5H [I]. Kfit qua ndy ngay lap tdc thu khac nhau tiiy thudc thdnh phdn hgp hut sy quan tdm cua cac nhd cdng nghfi thdc vd dieu kien cdng nghe, tii do dnh vi kha nang ung dung cua chung (he sd hudng nhifiu dfin cau tnic va cac tinh dp dien va hang sd dien mdi ldn) vd cdc chdt vdt ly cda san pham. Cac nghifin nha nghifin cdu co ban vi lan dau tien cdu co bdn nham tim hifiu co che hinh thu dupc hifiu dng dp difin Idn ddi vdi thanh tinh phan eye difin mdi Idn gdp vdt li$u dp difin khdng chi. Dgc difim phan nang cao he sd difin, ca ciing nhu quan ttgng nhdt cua hg BZT - xBCT, nghien cdu tdi uu hda cdng nghfi chfi khac vdi cac he khdng chi cdn lai, la sy tao cdc he vdt lifiu ndy dang frd thanh tdn tgi cua difim ba, giao difim giua ba van de thdi sy dugc quan tdm.
pha: mat thoi, td gidc vd lap phuang. Sy Bdi bdo nay chu yeu trinh bay vfi sy tdn tgi cua difim ba nay ddc tnmg cho tgo pha va mdt sd tinh chat chuyfin pha cdc hg vat hfiu cd tinh dp difin tdt frfin nhde cua he vat ligu BZT - BCT.
CO sd chi. 2, Thirc nghiem
Sau phdt hien cua Liu vd cdng sy. Dung djch rdn (1 - x)BCT - xBZT cdc v|t lieu tuong ty cung dugc chfi tgo dugc che tgo bang phuang phdp phdn bang cac phuong phap khac nhau va dng pha ran. Cac hda chdt ban ddu gdm cho cac thdng sd khd tot frong vung lan BaC03, CaCOa, Ti02, Zr02 vdi do tinh can bifin pha hinh thai hgc [2], [3], [4], khifit cao (> 99%) dugc phdi Hgu tiieo ' Truo'ng Cao dang Cong nghidp Hii6
^•^ Tnrong Dai hpc Khoa hgc - Dgi hgc Hua 104 '' Tmong Dai hpc Pham Van D6ng
TAPCHi KHOA HOC - DAI HQC DONG NAI, SO 04-2017 ISSN 2354-1482 hap thiic (1 x)(Ba<i,7Cao,3)Ti02
xBa(Zro,2Tio,8)03 (x = 0,44 + 0,52 la ty phdn Clia Ba{Zro,2Tio,8)03 hay BZT trong dung dich). H6n hcrp nay dugc nghien (lan 1) 20 gia trong dung moi ethanol b3ng may nghien hanh tinh (PM400/2-MA-Type) tdc do 100 vong/phiit sii dung bi Zirconia, sau do dugc sky kho va nung sa bo. Bot, sau qua trinh nghien lai (lan 2) 20 gia, dugc
^ 0
f-2
0 - 4
•"-6
Hinh 1: Gidn do phdn tich Cd hai difim mdt mat khdi lugng tdn tai frfin dudng cong TG iing vdi hai diem tiiu nMet frfin dudng cong dTG. Didm ttid nhdt xdy ra d 709°C, difim ttid hai dinh vi tai 927''C tirong dng vdi dfi hut khdi lupng Am, la 6,794% va 17,643%. Vd nguyen tdc, phdn dng hmh thanh dung dich i^n xay ra hodn toan d difira ttiu nhiet thd hai (dng vdi dp hyt khdi Iupng ldn nhdt trong dai nM^t dd ngMen cdu), ngMa la nhifit do nung so bd phai dugc chpn d Idn can 927^C. Tuy nhien, khdi lugng hgp ttidc dung cho phep phdn tich nMet (21.2 mg) rat be so vdi khdi lupng vat li^u cdn chfi tao mlu, do vdy nMet dO nung phai dugc chgn idn ban difim tiiu
ep thdnh vien dang dia va thieu ket d 1450°C frong 4 gid.
3. Ket qud va thdo luan 3.1. Nki$t do tqo pka
De chgn diing che do nhiet tgo dung dich ran ciia vat lieu, chiing tdi thyc Men phdn tich nMet TGA - DSC dfii vdi thanh phan x = 0,48. Dudng cong TGA - DSC dupc ghi vdi tdc dO lO^C/phut frong khdng khi (hinh 1).
709,I7°C ^ \ \
0
Am (mg) -1,478 Am (%)-6,974
200 400 6
xSv,
00 800 T{'C)
t
i-
100
•
927,55=C 0,1 'a -0,1 -0,2 -0,3 Am (mg) - 3,74 Am (%)-17,643
D 1200
1
onhiet cua ihdnh phdn x = 0,48
nMet tiid hai c& (250 - 300)''C, tdc la khoang 1250*'C. Dfi khang dinh difiu ndy, chiing tdi dd khao sat phd nMfiu xa tia X(XRD) cua bfit 0,48BZTdupc nung so bd d 1150°C, nOO^C va 1250°C (hinh 2).
...uiiizi::
20 30 40 50 60 70 80 26 o
Hinh 2: Gidn diXRD cua bQt 0.48BZT tgi cdc nhiet do sa bo
105
TAP CHI KHOA HQC - DAI HQC DONG NAI, SO 04 - 2017 ISSN 2354-1482 CJ nhifit dp I150°C, vat Hfiu tdn tai
nMfiu thanh phdn hda hgc khdng mong raudn, nhu BaossCao.uTiO*, BaCaTi04, CaTiOs. Khi nang nhifit do so bd Ifin 1200°C, ty Ifi tiianh phdn 0,48BZT cao hon dang kfi, song van cdn radt Iupng nhd 12R-BaTi03 [2]. Cdc chdt khdng mong raudn ndi frfin dugc gpi chung Id
thanh phdn khac. Tifip tuc ndng nhiet dg len 1250°C,vat lieu tiiu dugc cd hpp thuc hodn chinh vdi cau true perovskite.
Nhu vgy, nhiet dp nung so bd 1250°C dupc chgn la hgp Iy. Nhiet do nay cung dugc mgt sd tdc gia khac sd dung ttong cac nghifin cdu cua minh [7], [8].
3.2. Cdu true vd tinh ckdt diin moi
1
1
. v . . .
\ 1 , 1 L i i
. ^ j . . |
, I , i ;
1
- '- («)
- •, - X = 0 4H
- . - ' ! - x = 0 44
, " " ' . V
- / ' , ^ v ~
-',...'^-
['')
X = 0,52 - K = (1,5(1 - K = 0,48 - X = 0,4fi X = 0,A'\
20 30 40 50 60 70 20 (°)
44,0 44,5 45,0 45,5 45,0 46,5 26(0)
Hinh 3: Gidn do XRD cua cdc thdnh phdn vdt lieu thiiu kit tgi 145(fC Hinh 3a cho thdy, tat ca cac mau
deu cd cdu tnic perovskite, khdng phat hifin ddu vfit cua pha la frong pham vi nghien cdu. Difiu nay chdng td, dung dich rdn xBZT da hinh thdnh dn dinh.
Hmh 3b bieu dien gian dd XRD cua vat lieu frong khoang 44° -^ 46°. Cd the thdy rang, khi x <0,48, vdt lifiu cd ddi xiing hi giac (thudc nhdm khdng gian P4mm) ddc tiTmg bdi su tach vach (002)/(200) tgi ldn can 45°. Cdc dinh nhifiu xa (002)vd (200) ddn nhdp lara mdt khi X > 0,48, vat lieu sd hiiu ddi xdng raat thoi (nhdm khdng gian P3ra), nghia Id
da cd sy chuyen pha vfi cdu tnic. Cd thfi ndi, ty phdn BZT thay ddidd gay ra sy thay ddi cdu tnic tinh thfi vd kich thudc d CO sd ttong vat lieu. Hinh 4 bifiu difin su phu thudc ndng do BZT cua cac thara sfi ragng vd tinh tu giac cua vdt lieu. Vdi ndng dgx > 0,48, vat lifiu tdn tgi d pha tii giac, tham sd a^a^. va c = c.p dfiu tdng nhung mdc do tang cua a nhanh hon so vdi c nen tinh tii giac gidm. Khi ndng dg x > 0,48, vdt lieu cd ddi xdng mat thoi, cac tham sd tuong
"jmg (a„, c«) gidra.
106
TAP CHi KHOA HOC - DAI HQC DONG NAI, SO 04-2017 ISSN 2354-1482
4,0120
* , 0 I 0 0 - 4,0080- 1.0060- ,0040- .0020- ,0000-
(a)
MPB
^M V — V
. < I ••-
. 1.
• c/a
'-^ •
MPB' • 1
| -
(6) 1,0020 1,0015 1,0010 1,0005 1,0000 0,9995 0,44 0,46 0,48 0.50 0,52 0,44 0,46 0,48 0,50 0,52
X X
Hinh 4: Hdng sd mgng (a, c) vd tinh tie gidc (c/a) cda he vdt lieu xBZT Hinh 5 rad td sy phu thufic nhiet * ^ ^. cua vat lieu ttong difiu kifin tinh do cua phdn thyc e*", phdn do e', hang
sd difin radi va tdn hao dien mdi.
(nhifit do phdng tdn sd I kHz).
0000 7500 5000 2500
K = 0,44
e^
^^^ A
. = 0,46 — . = 0,48 — x 500
400 300 200 100
e^
A
,^£J%
^ 0 . 5 0 X = 0,52 1
3 2
1-1
tanS (%)
^ ^
• " ^
25 50 75 100 125
rfc)
25 50 75 100 125
rrc)
25 50 75 100 125
r(°c) Hinh 5: Suphu thudc nhiit do e*", e' vd tan S cua hi vdt lieu xBZT & dieu kiin tinh
Cd tiifi thdy, sy chuyfin pha sdt ^0 ting vdi dinh eye dai T^, dupc cho difin - thudn dien cd dgng ddi rdng vdi
hdng sd difin mdi cue dgi e^^,va nMet
Bang 1: Gid tri e^ va T^ cua hixBZT
ttong bang 1. Day la mdt dgc trung cua vat lieu sat dien relaxor.
JC
El
r„(°c)
0,44 6476 96,5
0,46 10277
93,6 0,48 12505
89,3 0,50 10676
87,6 0,52 9734 85,2 Ddi vdi cac sat dign tiiudng, quy
Mat e'"(r) fren difim Curie tudn theo dinh ludt Curie - Weiss dang:
1 7 - - T „
-. ( r > r j , (1)
frong do, C^ld hang sd Curie, phan dnh bdn chdt chuyen pha sat dien cua vdt lieu, T^ Id nhiet do Curie - Weiss.
Hinh 6 minh hga quy ludt €''(T) cua thanh phdn 0,48BZT dupc lam khdp vdi dinh ludt Curie - Weiss. Cdc gia tri thu dugc khi lam khdp sd ligu
TAP CHI KHOA HOC - DAI HQC DONG NAI, SO 04 - 2017 ISSN 2354-1482 he xBZT dugc cho trong bang 2.
e'"(r) voi dinh luat Curie - Weiss cua 3,0 2,5 I
2,0
" 1,5 1,0 0,5
20 40 60 80 100 120 140 T(°C)
Hinh 6: Quy ludt e'(T) cua mdu 0,48BZTdugc ldm khdp v&i dinh lugt Curie - PVeiss
Bang 2: Gid tri cua cdc tham sd dien moi thu dugc khi ldm kh&p so lieu e^CT) cda hi xBZT v&i phuang trinh (1)
^
T„, = 89,3°C^
X = 0,48
£.T,= M,TC
X
0,44 0,46 0,48 0,50 0,52
C„xlO'(°C) 1,75 1,92 2,23 1,88 1,49
7-.(°C) 99,4 97,1 94,2 91,7 88,5
TiCC) 113,6 112,0 108,3 105,1 101,0
Ar(°c) 17,1 18,4 19,0 17,5 15,8 Hinh 6 cho thay, mdi quan he
e^(T} khdng tuan theo dinh ludt Curie Weiss ttong vung nhiet do ( r „ -5- Tg), vdi Tg hay nhifit do Bum, Id nhifit dg ma td dd quy Mat e^(T) phu hgp vdi dinh lugt Curie - Weiss.
Trong vung nhifit do tten Tg, cac vung phdn eye vi md frong vdt lieu hoan toan bien mat, vat lieu tdn tgi d trgng thai thudn difin. Ndi each khac, vat ligu thfi hifin ddc tinh chuyfin pha nhde. Sy chenh lech giua Tg va T^ cd sy khdc nhau gifla cdc thanh phdn vdt lieu, do vdy, dgi lugng AT = Tg — T^
cung phdn dnh dgc tnmg relaxor ciia vgt lifiu (bang 2).
Dfi chdng minh frang thai chuyfin pha nhde cua hfi vdt lieu, chiing tdi sd dung dinh Mat Curie - Weiss md rdng d vung tten T^ [9]:
1 1 ( r - O ' ' '
^' < Ccw (2)
frong dd, Tp, C^.^ Id cac tham sd, ^ dugc gpi Id dO nhde, thu dugc khi lam khdp dinh Mat nay vdi sd lieu thuc nghiera (Mnh 7).
TAP CHi KHOA HOC - DAI HOC DONG NAI, SO 04 - 2017 ISSN 2354-1482
-6
3 -8
^ - 1 0 1 -1^
i ^ - I 4 .
§ - 1 6 -18
'^^^
i^^SS^ t = 0.52, TJ = J ^ ^ 1 X = 0,50, lp = X = 0,48, i|i =
^ K = 0,46, T|. = K = 0,44, -to =
i.m^
1,794 1.825 ,757 .633
0 1 2 3
i n ( r -
Hinh 7: Syphy ihugc e''(T) dugc ldm kh Ket qua thu duac tten hinh 7 cho thdy, khi tdng ty phdn BZTfrong vat Hfiu, do nhde bifin thifin tu 1,633 (x = 0,44) dfin 1,825 (x = 0,48), nghia Id cd sy chuyen pha nhde ttong vdt lieu, va gora the hifin muc do bdt trdt ty cao.
0 viing nMet dO cao, hdi 6ap dien mdi theo nMfit dp, t * ' ( r ) , cd the dupc md td he thdc thuc ngMgra dang Lorentz (cdn ggi la dang toan phuang) [10]:
p V&i dinh ludt Curie — Weiss ma rdng
Cr-T,y
= i-i--
2 « (3)
^ S(5 liCu IhiK DgtuCm .— Dircmg ly ihuyfit
vdi, r ^ C ^ T ^ ) vd e^ Id cdc gid tri tai dinh, S^mo td rauc do nhde cua dinh Lorentz.
Hinh 8 Id kfit qua lam khdp sd ligu thyc nghifim vdi bifiu tiidc (3), cdc tham sd dgc trung dugc liet kfi frong bdng 3.
10000- 7500
^— S5 ueu Ihuc nghiem
— DirSme IJ ihuyC:
iO 90 100 UO 120
r(°c)
0 , 4 8 B Z T 12O0O- I. 9000
6000
60 70 80 90 100
m S6 lifiu Lhuc nghi&m - Dirfrng ly ihuyA
80 90 100 l i o 120
r(°c)
TAP CHI KHOA HQC - DAI HQC DONG NAI, S6 04 - 2017 ISSN 2354-1482
1 2 0 0 0 - | o , 5 0 C z X 9000-
30O0 ^ 56 lifiu thin; nghi6m
— EhrtBDg IJ Ituyei 10000
7S00
^— SS lifiu lhuc n ^ i d m
— Diiimg ly ihuytfl
60 70 80 90 100 UO 120 ^0 ' « 8° 5" ' ™ " O '^O
r ( T ) T(°C) Hinh 8: Hoi dap dien moi theo nhiet do dugc ldm kh&p v&i dgng todn phuang (3) doi
v&i hi vgt lieu xBZT
Bang 3: Cdc gid tri ldm kh&p sd lieu thuc nghidm v&i biiu thiec 3 cua hi xBZT
X 0,44 0,46 0,48 0,50 0,52
T,('C)
95,5 93,1 88,7 87,7 86,8
^a 6549 10150 12473 10588 9729
«a 16,6 17,3 18,7 18,3 17,6 Co thfi thay, sd lieu thuc nghiera cd
sy phu hop tdt vdi bifiu thdc dang toan phuang d phia nhifit dp cao. Sy sai khac dupc thfi hien rd rang d pMa nhiet do thdp. Thara sd 5^ phan anh do nhde cua dinh Lorentz, frong khi tham sd V md ta do nhde cua dinh chuyfin pha frong vat lieu. Sy phu thuge cua chiing vdo ndng do BZT bien ddi theo cung radt quy Mat va dat dinh tai x = 0,48 (hhih 9).
4. Kk lu^n
Tren co sd phep phan tich nMfit va nhifiu xa tia X, chung tdi xdc dinh dugc nhiet do tao pha (1250°C) vd chfi tao thdnh cdng dung dich ran (1 - x)BCT - xBZT bdng phuang phdp pha ran. Hdi dap difin mdi - nhifit dp chung td hfi vdt ligu sd hflu dgc tinh chuyfin pha nhde.
Tinh chdt dien mdi tdt nhdt thudc vfi thanh phan 0,48BZT lam cho nd trd thanh mdt ddi tugng vat lieu hdp dan cd nhifiu trifin vgng dng dung hudng tdi thay thfi cho cac vdt lifiu fren nfin chi.
0,46 0.48 0,50 0.52
Hinh 9: Suphu thuge cua tham sd 6a vd tp vdo nong dg BZT
TAP CHi KHOA HOC - DAI HOC BONO NAI, SO 04 - 2017 ISSN 2354-1482 TAI LIEU THAM KHAO
I . W . Liu and X. Ren (2009), "Large Piezoelectric Effect in Pb-Free Ceramics", Physical Review Letters (103), 257602
2. W. Li, Z. Xu, R. Chu, P. Fu, G. Zang (2011), "High piezoelectric dss coefficient of lead-free Bao,93Cao.o7Tio.95 Zro.osOs ceramics sintered at optimal temperature". Materials Science and Engineering B (176), pp. 65-67
3. W. Li, Z. Xu, R. Chu, P. Fu, G. Zang (2010), "Polymorphic phase transition and piezoelectric properties of Bai - xCaxTio9Zroi03leadfree ceramics",/*/y«'cfl B (405), pp. 4 5 1 3 ^ 5 1 6
4. M. C. Ehmke et al, (2012), "Reduction ofthe piezoelectric perfomiance in leadfree (1 ~ x)BaZro.2Tio gOs xBao.7Cao,3Ti03 piezoceramics under uniaxial compressive stress". Journal of Applied Physics (112), 114108
5. Dang Anh Tuan, Nguyen Trong Tinh, Vo Thanh Tung and Truong Van Chuong (2015), "Ferroelectric and Piezoelectric Properties of Lead-Free BCT - xBZT Solid Solutions", Materials Transactions, Vol. 56, No. 9, pp. 1370 to 1373
6. Dang Anh Tuan, Vo Thanh Tung, Truong Van Chuong, Le Van Hong (2016),
"Influence of sintering temperature on structure, microstructure and piezoelectric properties of doped BZT—BCT ceramics". International Joumal of Modem Physics B, Vol. 30,1650258
7. Y. Cui et.al, (2012), "Lead-free Bao.gsCaj isZro.iTio.gOg- CeOi ceramics with high piezoelectric coefficient obtained by lowtemperature sintering". Ceramics hitemational (38), pp, 4 7 6 1 ^ 7 6 4
8. Y. Cui, X. Liu, M. Jiang, Y. Hu, Q. Su, H. Wang (2012), "Lead-free (Bao.7Cao3)Ti03 - Ba(Zro.2Tio.8)03 - wt% CuO ceramics with high piezoelecfric coefficient by low-temperature sintering". Journal of Materials Science: Materials in Electronics (.23).pp. 1342-1345
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Technological Sciences, 52(8), pp. 2180-2185
PHASE FORMATION AND DIFFUSION CHARACTEMSTICS OF LEAD- FREE (1 - x)BCT - xBZT MATERIAL SYSTEM
ABSTRACT
This paper presents some results of research on structure and diffusion behaviour of BZT -BCT system. Accordingly, the structure and lattice parameters of the materials were changed as increasing BZT concentration. Besides, the dielectric - temperature responses reflected diffusion characteristics ofthe materials.
Keywords: BZT- BCT, diffiision transition, lead-free
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