No OSJune 2018ls6 08 - Thing 6 nam 20I8|p,S5-6O
T A P c m K H O A H O C DAI H O C T A N T R A O ISSN: 2 3 5 4 - 1 4 3 1
http://tckh.daihoctantrao.edu.vn/
Tinh chat quang - tir cua v|lt lieu BaTiOs pha tap Fe t^i viing bien pha cau triic
Nguyen Thi Nggc Mai", Nguyin Chi Huy", Lai Thi ffoi Hdu". Nguyen ViSn DtSn^' ' Trudng Dgi hpc Khoa hpc - Dgi hpc Thdi Nguyen
Email: [email protected]
T h S n g tin b&i vi4t T d m t a t
Ngdy nkgn bdi:
06/5/2018 Ngdy duyit dang:
12/6/2018
Tit kkod:
Fe-BaTiOs. vgt hfu da pka difn lit, hap thi^, huynh quang, tinh chdt quang-lii.
V a t l i c u d a p b a d i e n t h B a T i l - x F e x 0 3 (0.0 < x < 0,18) dupc ch^ tao bang phuong phap phan hng pha rln. Su chuydn pha cau tnic v i tinh chat quang - th ciia vgt lieu d3 dupc khao sat chi ti^t, Ket qua cho thly. khi Fe thay the cho Ti, clu tnic ciia vgt lieu chuydn th th giac (P4mm) sang lue giac (P63/mmc). Su xult hi$n ciia cac mirc tgp chit Fe kit hpp vai cic miic tap do su khuyet thieu oxy, sai h6ng mang tao n£n sy chong chap, md rpng dii hap thu va lim djch b6 hap thu ve phia hxidc song dii. Chiing toi ciing chi ra ring, cac ion Fe3+ v i Fe4+ da thay thi cho ion Ti4+ trong clu tnic tii gi^c vk luc giic ciia vat li^u BaTi03, Chiing tdi cho ring, tinh chit sit tir ciia \%i lieu BaTil-xFex03 co nguon goc th nhffng sai h<!ing mang v i tuong tic hao d6i giOa cac ion Fe3+ va Fe4+,
Mfl^dau
Vgt li|u da pha d i ^ tu (multiferroics) h i ^ dang danh dupc si quan tim nghi&i eiiu ciia nhilu phong thi nghiem hen the gioi vi hiia hen tiem ning iing dyng hong eac fliiet bi dien til da chiie ning [1.2], Vat lipu dupe coi la multiferroics neu ttic hi$n ddng ton tgi ci tinh chit sit di^n v i sit tir Phuong phap tgo ra vSt li^u multiferroics dgng don chat la dua cic tgp chit th tinh vao mang tinh the ciia vgt lieu sit dien [2,3,4], BaTiOs (BTO) la mot vgt lieu dien moi. sit di^n vii ip dien dien hinh va ion Ti c6 thi d l dang dupc thay the blng cdc ion krni logi chuyen hep nhu Fe, Mn, Co,., nen la m0t ling vien tot cho muc dich niy Gan diy. nhieu nhom nghien cmi d3 thu dupc dgc tinh mulhferroies ciia vSt lieu BTO pha tap Fe cr nhipt dp phong [2,3,4,9] Tuy nhi£n, CO rit it bio do nghien chu dly dii dnh chit quang-Hr ciia vgt li§u BTO pha tgp Fe khi hong mlu ddng tdn tai ci hai pha clu hiic th giic (t-BTO) v i lpc giac 0»-BTO). die bipt l i cac die trung sit tir 6 bien pha hinh ttiii hoc, Ngoai ra. tinh chat sit hr a nhiet dp phong ciia vit lipu BTO pha tap Fe mjc dii di dupc mpt sd bao cao de c^p din [2,3,4,9] nhung con nliieu dilu
chua ttiong nhat. Trong bai bio niy. chiing tfii trinh biy m$t sd kit qui nghien chu hnh chit quang-hi ciia vat lieu BaTiO] pha tgp Fe tgi viing bien pha can tnic bi giic v i luc giae,
Thve nghiem
Cac miu da hnh flie BaTii^FCxOs ( x = 0,0; 0,08 < x
< 0,18) dupc chi tgo blng phuong phap phin iing pha rin, Cic hoa chat ban dlu la- FcjOs, BaCOj, TIOT VOI dp sgch tr6n 99.99% Sau khi can ttieo diing hpp thiic danh djnh, hon hpp sS dupc nghien trpn blng cdi ma nao, ^ viSn v i nung so bp 6 nhiet dp 1050°C hong 24 giir. Sin phim sau d6 dupc nghiln hpn va ep vien lan hai, cuoi Cling dupc ep vifin va nung ttueu ket cr nhipt do BOO^C hong thoi gian 5 gicf. Do sach pha v i clu tnic tinh ttie ciia mau dupc kilm ha bing phuong phap nhieu xa ha X Phep do phd hip fliy dupc fliyc hifin hfin he do JACO V- 670 Phep do phd hu^nh quang dupc do o che dp dhng hfin hp do hu^nh quang phSn giii cao ciia hSng HORIBA JOBIN YVON P h ^ do duong cong bi he duoc tiiyc Jiifin hen hp do cic tinh chat vgt 1^ PPMS 6000 Phfip do phd c$ng hudng spin difin bi(ESR- Electron spm Resonance) dupc fliyc hifin trfin hfi JEOL-TE300 cr tan sd
' 55
NVDangel0//N0 OSJune2018|p 55-60
kich fliich 9,45 GHz (X-band), Tat ca cac phep do deu Ihyc hipn o nlufit do phong,
Ket qua va thao luan
2^vJu^
0 J 4 A A _ J L ^
'I I lo.i?ir r • %
. K1 kio^TTirTT"
A. PP-'> irt , / l r
ddi bi 44 - 46° chiing toi da thu dupe kit qua nhu hen hinh 2 (khi tinh toin sd lifiu, miu BTO dupc coi la chi tdn tai clu tnic t-BTO voi ty le la 100%). Th hlnh 2 ta flily, khi X = 0,08 pha h-BTO da hoin toan chilm uu flie v i chiem hfin 9 1 % , ty phan pha t-BTO tdn tgi hong mlu la rat nho va chi chiem gan 9%, Khi ndng dO pha tap x = 0,12 clu tnic th giic di chuyen hoin toin sang cau tnic lye giic Nhu vgy, co thi coi viing pha tap 0,08 ^ x < 0,12 chinh l i viing bifin pha clu triic, noi vira co su ddng tdn tgi. cgnh tranh v i chuyin hoin toan tit cau tnic t-BTO sang h-BTO.
G6c 28 (dp)
Hinh 1. Gidn do nkieu xg tia X cda vgt hiu BaTi,.
J'e/Di (0,0 <x< 0,18)
Hlnh 1 li ket qui phan tich gian dd nhieu xg tia X (XRD) ciia cac mau hong khoing goc 19 bi 35° din 65°. vdi bude quet 0,02". Kit qui cho fliay, cic dinb phd c6 cudng dp manh v i rit sic net chiing to cac mlu hoan toan sgch phg, kit tinb tdt v i it sai hong. Khi chua pha tgp (x = 0,0) vgt heu BaTi03 co clu hiic tli giic (t-BTO) thuOc nh6m khong gian P4nun Khi thay the Fe cho Ti clu hiic th giac din chuyen sang cau tnic lyc giic (h-BTO) e6 nhom ddi xiing khong gian P63/mmc Khi x tang, cu6ng dd cac vgch nhifiu xg dgc trung cho pha lyc giic tang din, cu6ng d0 cac vgch nhilu xg dgc trung cho phg bi giic gigm din vg bien mat khi x= 0,12. Khi ndng do Fe ting cao den 18%, mpt sd vgch nhieu xa d|e trung cho cau tnic lye giic bit dlu tich thanh hai vach, chiing t6 co su bien ddi hong eau tnic tinh the,
Quan sat hen gian do XRD eOng cho thay khi ndng do pha tgp co gia hi (0,08 5 x S 0,11), cic vgch nhilu xa d|e hung cho pha tii giac c6 cucmg do nho. giim din va biln mit khi x =0,12. dieu nay gpi ^ ring diy e6 the li vimg bien pha clu tnic khi elu tnic t-BTO chuyin hoan toan thinh h-BTO Vth myc dich xic dinh rS viing bifin pha cau tnic niy, chiing toi da Uen hinh dinh gia dyfli lupng ty phan ciia bai pha clu hiic hong v?lt lifiu flieo ndng dO pha tgp x. Theo [3.4] khi % tang cu6ng do cac vgch nhilu xg dgc hung cho pha b- BTO ting din, cuimg do cic vgch nhifiu xg dac hung cho pha t-BTO giim din Blng each lay gig tri dipn tich vach nhieu xg iing vin cic mlu don pha t-BTO (hole h-BTO) lam chuan sau d6 so sanh gia hi dien tich vgch nhilu xg ciia mlu cin xac djnh, ta sfi tinh dupc ty phan dong gop ciia mdi pha tinh flil co trong mlu vat lifiu, Khi sii dyng chucmg trinh profile phin tich dien tich vgch nhilu xa hong viing goc 29 thay
Nong dp Fe thay th^ cho Ti (x) Hinh 2. Ty li kai pha cau true eua vgt lifu BaTi/.
xFejOj thay doi theo ndng dp thay the Fe (x) Hinh 3 li kit qui do phd hap thu ciia cac mau trong khoing budc song hi 300 den 1200 nm Chiing ta de ding nhan tiily, mau khong pha tgp bilu hifin hap fliu chuyin mhc thing eho phep voi b& hip thy tgi bucic song khoang 400 nm. Dp rong viing cam ciia vat lipu BaTiOj CO thi duoc xic dinh gan diing ttieo cong fliiic'
_ he 6,625.10"" 3 10' 1242,19 E,=—• = - i —
* X X
«3,l(er) X X{nm) hong d6 X la buoc song hip thy Kit qua niy hoan toin phli hpp vol cic c6ng bd v l dp rpng viing elm ciiavatlifiyBaTi03[3, 5],
^(nm)
56 I
JV.r.ZJong e/fl;/No,0SJune2018|p,55-60
Hinh 3. Phd hdp thy cua vgt lieu BaTi)J^e/?3 (0,0<x<0,18)
Tli Hinh 3 ta thly, hb hip ttiy ciia cic mau pha tgp khong c6n sle net v i dich ve phia buoc s6ng dii, viing hap thu mo rOng ve phia n3ng lupng thip Voi cic miu pha tgp hen 10% viing hap thu viing hip fliy gin nhu md rOng hong toin giii budc song do, Tiie l i cic man co khi ning hap thy toin b$ anh sang trong vimg khi kien v i mpt phan hong vung anh sing hdng ngogi Theo [S], su ddng tdn tgi hai logi can tnic tii giac v i luc giic hong vgt lifiu khi (0,08 < x < 0.12) c6 the din din nhoe bo hip thu Su dich At ciia b6 hip thy va su mcr rpng vilng bap thu ciia vgt lieu BTO, BTO pha tap Cr, Fe, Mn.. cung da dupc cac bio cio [2.3.6] d l cap din Theo do, ket qui do phd hip thu rat phy thupc vio logi ion thay the, ndng do thay the, dieu kifin che tao mau.,. Ben cgnh do, su thay ddi hgng thai hog tri cua cdc ion tgp chit, sy khuyit thilu dxy do sp co mat ciia cic ion tgp chat dong vai ho quan trpng vio sy dich do ciia bo hap thy va su mo rong viing hip thy ciia vit lifiu Nhu vay, cic die dilm tren phd hip thu ciia cac mlu don pha lyc giic (0,12 < x < 0,18) cung CO thi dupc giii thich nhu sau phd hip thy thu duoc la sy tning chip ciia cie chuyen miic viing - viing, viing - tgp, tap - tap va tgp - viing. Khi ndng dp Fe hay the cho Ti ting cao, cic miic tap chat xult hifin hong viing elm ting nen miic d^ tning chgp ciig cac chuyen miic viing - tgp v i tap - tgp ting, din den sy md rpng dai hip thy nhu quan sat thly hen Hinh 3. Chinh su hiing chap v i md rpng viing hip thy khi c6 mit ciia cie mhe tap nen rat kho de xic dinh chinh xic bd hap ttiy cung nhu d$ r^ng viing elm ciia cic mlu.
Hlnh 4. Pho huynh quang cua mpt so mdu dgi difn cko hi BaTiiJ^ejOi (0,0 <x < 0.18)
D l CO thfim thong Un gitip h i ldi cau hdi ring khe ning lupng (dO rpng viing elm) ciia vgt lipu BTO cd
bi fliay ddi (giim) khi cd mit ciia tgp chat hay khdng.
cic phfip do phd huj'nh quang ciia m^t sd miu dgi difin cho hfi miu di dupc fliuc hien Kit qua do phd hu^nh quang (PL) d nhifit do phong, vdi ngudn kieh thich laser budc sdng 266 nm, ciia m^t sd miu dgi difin dupc trinh bay trfin Hinh 4. Ket qua cho thly, phd PL ciia mlu BTO chi bao gdm m$t dii phit xa rat rpng co cudng dd lon, dinh trung tam dat cue dgi tgi gin 466 nm (2 66 eV) v i cd dd ban rpng khoing 120 nm Cic mlu cd su thay thi ciia Fe cho Ti dlu co cudng dp bu^nh quang giim maiUi va thu hep d$ bin rong ciia dinh phit xg trung tgm rit ro Kit qui nay efing hrong ddng vdi cac cdng bd eiia nhdm [7,8]. Khi ndng dp pha tgp tang cao, cudng do PL nhd chiing td kha ning phit huj'nb quang ciia cic mau giim, vi tri dinh cihig gin nhu khdng thay ddi khi x ting Chiing td sy cd mgt ciia tgp Fe da giy ra hieu iing d|p tit huynh quang hong vit lieu BTO, Co ttie khi Fe ttiay flil cho Ti trong mgng BTO dS lim cho clu tnic tmh the ciia BTO kem hoan hio (sgi hdng mgng, mit khuyit dxy v i cac miic tap chit ) lim xult hifin thfim cac kenh tai hpp khdng biie xa lam giim cudng dp huynh quang Ngoii ra, hong phfip do pho PL, ning luong photon ciia ngudn kich thich l i khoing 4 6 eV, dii lon dl xiy ra nhflng chuyen ddi true tiep viing-viing Phd PL ciia cic mau pha tap rat gidng phd PL ciia BTO, chi bao gdm mdt dai phat xg rat rpng nen dii phat xa niy phai ling vdi nhttng chuyen ddi true hep viing-viing Vi tri dinh ciia dai phit xg niy cung gin nhu khdng thay ddi khi X ting, chiing td khi Fe fliay flie cho Ti trong mgng BTO chi lam xuat hifin cac sai hdng mgng, mit khuyit dxy v i cac miic tgp chit ddng vai hd rfliu cic kenh tii hpp khdng biic xg lim giim cudng dp huynh qugng. Tiic la, su cd mit cha tap chat Fe khong lim giim khe ning lupng ctia vat lifiu BTO nhu di quan sit thly hen phd hip thu
De CO nhthig thdng tin chi tiet v l tmh chat th ciia v|t lifiu tai vimg bien pha clu tnic, chiing tdi d i thyc hifin phfip do phd cOng hudng spin difin tii (Elechonic spin resonance - ESR) vdi tin sd kich thich v = 9,45 GHz Trong phfip do nay, mdt lupng miu bdt cd khdi lupng 20 mg dupc ngp vio mpt dng fliach anh va dit hpng khoang cpng hudng, npi tir hudng cd thi ttiay ddi tli 0 den 21 kOe, Phd ESR ciia mpt sd mlu dgi difin cho he mlu hong viing tir trudng th 2,0 den 5.0 kOe dupc bieu dien hen Hinh 5, Ta ttily. tit c i cic mlu pha tap dlu ton tgi mpt dinh cpng hudng (ky hifiu Ll), cudng dp ciia dinh niy ting v i dgt gii tq dn dinh
^7*
N.VDang et al /No.OS J u n e 2018lp.55-60
khi x = 0,12 Vdi cic miu cd 0.08< x < 0,11, ngoii L|
edn cd m$t dinh cdng hudng khic cd cudng dd mgnh d viing tli trudng flilp (ky hieu LT), Dinh chii y l i cudng do ciig Lj gan nhu biln mat khi x > 0.12 Ta thay.
gii hi hi trudng cOng hudng (Hj) ciia hai dhih L] va Li cd gia tn khoang 3395 O e v i 2100 Oe Sh dyng cong ttiiic g
= h vifj^r, (hong do g la thira sd Landfi, h, f va / ^ li hing sd Plank, tin sd vi magneton Bohr brong iing), ta lan lupt thu Arpc cac gji tri ciia g la ~ 1,98 vi - 3.21 tuong hng vdi hai dmh Li va L; Nhu vgy, ddi vdi dfaih cdng hudng Lj gia tri ciia thura sd Lande tuong duong vdi gii tri ciia cic electron tu do (g = 2 023) sS tuong iing vdi cac tupng tie spm-spin v i die trung cho tinh chit fliuan bi (PM) [9,10]. Nban djnh niy flil hifin rit rd hen phd ESR ciia cic mau cd x > 0,12 Cd flil tuong tic ludng cue - ludng cue (nbu Fe*^ - F e ^ ddng gop chinh vao cdng hudng L^ va cd hfin quan d ^ cic tuong tic sit tir (FM). Tg thly L2 cd cudng dp mgnh vi phd ESR cd su bat ddi ximg khi x= 0,11. Cd the sp ddng tdn tgi ciia cie tuong tac FM va PM hong mlu dS tao ra su thay ddi trong vimg Hr ciia Lj,
< 0,14). Dua vio hinh dang ciia dudng cong M(H), tii hnh ciia vgt lifiu BaTiLxFe^Oj (0,0 < x < 0,18) cd flic phan thinh ba miln die tnmg la; (i) jc = 0,0 -^ 0,08; (ii) X = 0,11 - 0,12 vi (iii) x: = 0,14 -H 0,18
2,0 25 3.0 3.5 4.0 4.5 5.0
H(kOe)
Hmh 5. Phd ESR cua mpt sd mdu dgi difn cho kf BaTi,J^e/)3(0,0< x<0.18)
Rit phu hpp vdi dtt lifiu ESR, kit qua do dudng cong tut h i (hinh 6) cflng cho flily chi tdn tgi tmh chat sit tir d nhifit dp phdng hong cac miu pha tgp 0,08 < x
0.05 i
-0.05
. - • — X = 0,08 jgg^
, . - ^
(a)
• — • — x = 0,11
• - - x = 0,12
1 , ^
^
(b) :
0,08 0,04
^ - 0 . 0 4 -0.08 -0.12
— • — X = 0, 14
• - » — x = D,16
— * — x = 0,18
- y ^
r . . . i . . . .
' v(3
(c) :
:
,...,,..,•
-1 10* -5000 0 5000 1 10^
H(Oe)
Ifinh 6. Dudng cong tit tre cua vgt lifu BaTii.
J^e/)3 (0,0 •<x< 0,18)
Doi voi viing sit tur thii nhlt, tii dp ciia cie miu c6 gii hi ting dan khi ndng dd Fe fliay flie che Ti ting Theo chiing toi, Unh chat sit tii ciia mlu c6 the lien quan din su cgnh hanh trong tuong tac tir gitta cac ion Fe hong clu tnic tii giic v i lyc giac khi, Cy ttil li, ddi vdi pha th giac, cac ion Fe** va Fe**" sfi thay dil mdt phln ion Ti""^ hong mgng tinh flil ciig octahedra TiOg v i tuong tac gitta cac cip ion Fe'^-Fe** la tuong tie sit th (FM), tuong t i c gitta cac cgp ion Fe'^-Fe" va Fe''*-Fc^* [3]. Ngoii sy biln ddi ciia ty lfi ion Fe** va Fe** hong mlu theo ndng dp thay thi x, vj tri ciia cac
JV J:amge(fl//No.08June 2018|p 55-60
ion Fe thay the vao vj tri cila Ti cflng dong vai hd quan hong vao tir tinh ciia vgt lifiu [2], Khi pha lyc giic chiem uu the flii hong vgt lifiu BaTii-^Fe^Oj tdn tai eac mang octahedral T12O9 va co hai n tri ciia Ti la Til va Ti2 m i ion Fe co thi fliay the [2,3]. Khi dd tucmg tie gitta cic ion Fe tgi cic vj tri Til vdi nhau v i cac ion Fe tai vi tri Ti 1 vdi cic ion Fe tai vj hi Ti2 vdi nhau la yeu v i ehi ddng gdp vio tinh chat thuin br Cac tuong tie giita cac ion Fe tgi vi hi Ti2 vdi nhau (Fe (2) - Fe (2)) cd flil la sit tir hoic phin sit br Theo [3], brong tac gitta cic ion F e ^ (2) - Fe** (2) l i sit tur. hiong tac gifta cie cip ion F e ^ (2) -Fe** (2) v i Fe** (2) -Fe** (2) la phan sit tur Vdi dtt lifiu thu dupc hfin hinh 6a. chiing tdi cho ring tir do ciia cic mlu khi x = 0,08-0,10 chii ylu la do tuong tic sit hi ciia cip ion Fe**-Fe** hong pha tli giic vi khi do ty phan pha bi giic chiem uu flie v i Idn bon 90% (Hiifli 2). Theo [4] sd dxy hda ciia Fe dat gii tri Idn nhat tgi r - 0,11 ^ 0 12 nen vdi ty lfi pha tgp nay ndng dd ion Fe** hong mlu l i cue dai Sau do neu tiep tuc ting ndng do Fe ttiay the eho Ti, sd oxy hda cua Fe v i ndng dO ion Fe** hong mau giam Chiing tSi cho ring, cic d$c trung sit bi ciia mau khi 0,11^ X ^ 0.12 (miln ttni hai) vln Ii ddng gop cila pha h-BTO vi cau tnic h-BTO la cau hiic cd loi cho hnh chit th ciia vgt lifiu BaTi|.xFexO [2.3].
Ngoiira.su phu thupc ciia luc khing b i ^ ^ v i o x hongkhoingO.il £ r £ 0,12 ciing rat ding chii y. Co thi thly ring. He dat gii tri eye dai k h i x = 0.12 va glim mgnh khi x ting, ddng thdi tir dp ciia mlu cung ed xu hudng giam Tinh sit bi ciia hfi mlu tdt nhlt khi 0,11 £ x ^ 0,12 vdi tir d$ bSo hda Idn va luc khang tir Idn nhlt tai x = 0,12 (He - 3 0 kOe) (xem Hinh 5 b) Cd le khi 0,11 £ X £ 0,12 da t^o ra mpt ty Ie tuyfit vdi gitta hai pha clu tnic cflng nhu nong dp cac mit khuyet dxy trong miu m i su ddng tdn tgi, canh hanh va lai hda gitta chiing d i dan din gia tr) tdi uu cua He va lam cho tuong t i c sit tit gitta cic ion Fe** tgi cic vj tri Ti(2) chiem uu thi Tuy nhien, neu ndng dp x h ^ tpc ting cao 0,14< X < 0,18 sS dan den hifin tucmg suy giam manh tinh chit sit th v i vgt hfiu flil hifin nhu mdt vgt hfiu fliuin tir, Cd thi cd hai nguyfin nhan din din su giam ciia tinh sit tir dd li; ndng do ion Fe**
hong mlu giam. ndng dp ion Fe** hong mlu tang, lim cho hrong tic sit th gitta cic ion Fe** - Fe** giam Ngoii ra, khi vat hfiu don pha h-BTO (li mdt pha kfim ben) nen su loai bd mdt hole th|m chi hai ion 0(1) ttt cic Idp Ba(l)0(l)3 l i can ttiilt d l dn dinh pha h-BTO a nhipt do phdng [2], Sp gia ting ragnh ciia cic nut
khuyit dxy sg lim cho cac ion Fe** bi cd l§p, cie tuong tic hao ddi flidng qua dxy bi xda sd v i lim cho tmh chit sit bi giam mgtfli Su giim mgnh ciia h | t tif sit hr ciia v | t lifiu da tmh the BaTiosFeoTOj. don cau tnic h-BTO khi ndng do Fe thay thi cho Ti rat cao (x
= 0,7) cttng dupc quan sit thay hong mot cdng bd gin day ciia Lm v i cic cong sy [2].
Ketlu^n
Blng phuong phip phan ling pha rln, chiing tdi da cbl tgo ttiinh cdng vgt hfiu dg pha difin tir BaTii.
xFcxOs (vdi 0,0 < X < 0,18) hoin toan sgch phg va diing hpp thhc danh dinh Cic phep do XRD, phd hip thy UV-Vis. phd huynh quang. phd cpng hudng spin difin th v i bi dp cho thay cac ion Fe di fliay thi cho Ti hong clu hue ciia vgt lifiu BaTiOs v i giy ra sy bien ddi clu tnic th bi giac sang luc giic. Tgi vOng bien pha clu tnic su xult hien ciia tap Fe kit hpp vdi su khuyit thilu dxy, sai hdng mang, di inh hudng manh lfin tinh chat quang v i tir ciia vgt hfiu EgTiOj.
L&i cam on
Nghifin ciiu niy dupc tai h p bdi dl tai d p Qudc gia thy$c Chuong hinh phat tnln V|t ly din nim 2020. m i sd DTDLCN.35/18
T A I L I $ U THAM KHAO
1. G Manfred Fiebig. Thomas Lottermoser, Dennis Meier and Morgan Trassin (2016), Tke evolution of multiferroics. Nature Reviews 1, 1-14.
2. F. Lin, D. Jiang, X Ma and W, Shi (2008),
"Influence of doping concentration on room- temperature ferromagnetism for Fe-doped BaTiOj ceramics", J Magn Magn. Mgter. 320, pp, 691-694;
3 N V Dang. T. D Thanh, L. V Hong. V D Lgm, and The-Long Phan (2011), Structural, optical and magnetic properties of polycryslallme BaTi,.
J^eJ^i ceramics, Joumal of Applied Physics 110, 043914-7:
4 Ha M. Nguyen, N V Dang, Pei-Yu Chuang, T, D. Thanh, Chih-Wei Hu, Tsan-Yao Chen, V, D, Lam, Chih-Hao Lee and L. V Hong (2011), Tetragonal and hexagonal polymorphs ofBaTiuJ^e^ss multiferroics using x-ray and Raman analyses. Applied Physics Letters 99. 202501-3;
5. Yukikum Akishige, Youichi Ygmazaki and Nobuo Mdri (2004), "Pressure Induced Insulator-
\:-^i^^M
N.V.Dangetal/tia OSJune 20I8|
Metal Transition in Hexagonal BaTi03.j", Journal of tke Physical Society of Japan 73 (5), pp. 1267-1272,
o. Shubm Qm, Duo Liu. Zbiyuan Zuo, Yuanhua Sang, Xiaohn Zhang, Feifei Zheng, Hong Liu. and Xian-Gang Xu (2010). UV-lrradiation-Enhanced Ferromagnetism inBaTiOj, J. Phys. Chem. LeU 1, 238,
/ M F C . Gurgel, J. W, M, Espmosa, A B Campos, I L. V, Rosa, M. R. Joya, n. G. Souza, M
«. Zaghete, P, S. Pizani, E, R Leite, J. A Varela, E Longo (2007). "Phololumineseence of crystalline and disordered BTO:Mn powder- Experimental and theoretical modeling", Joumal of Luminescence 126.
pp, 771-778,
Magnetic and optical properties of Fe - doped BaTiOd materials at the structural phase boundary
Nguyen Thi Ngoc Mai, Nguyen Chi Huy, Lai Thi Hm Hau, Nguyen Van Dang
8 Ming-Sheng Zhang. Jian Yu, Wan-chun Chen and Zhen Yin (2000), "Optical and struclral properties of pure and Ce-doped nanociystals of barium litanale". Progress in Crystal Growth and Characlenzlion of Materials, pp 33-42,
9 Soumya Rajan, P.M Mohammed Gazzali, \j Chandrasekaran (2017), Impact of Fe on structural modification and room temperature magnetic ordering in BaTiOj, Speclrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 171, 80-89,
10. M Ikeya, New Applications of Electron Spin Resonance (Worid Scienhfic, 1993).
Article info
Recieved:
06/5/2018 Accepted:
12/6/2018
Keywords:
Fe-BaTi03 Multiferroics.
Absorption, Phololumineseence.
Opto-magnetic properties.
Abstract
Multiferroic BaTiI-xFex03 (0,0 < x < 0,18) materials were synthesized by the solid-state reaction method. The influence of Fe substitution for Ti on the crystalline structure and opto-magnetic property of BaTil-xFex03 samples was investigated The results revealed that, the structure of the material sensitively depended on Fe dopant content, A, and hansformed gradually from the tehagonal (P4mm) phase to the hexagonal (P63/mmc), The presence of Fe impurity levels combined with flie complex levels due to lack of oxygen defects and lattice defects created overlapping lattice, expanded the absorption band and provided the absorption edge toward longer wavelength.
We also point out that Fe3+ and Fe4+ ions substitute for Ti4+ and prefer locating in the tchggonal and hexagonal BaTi03 shuctures, respeehvely It seems ttiat, ferromagnetism in BaTii-xFex03 is related to lahice defects and/or exchange interactions between Fe3+ and Fe4+ ions