1
S ess elease induced piezo esponse in lead- ee piezoce amics
wi h high-symme y mo pho opic phase bounda y
Xa ie Vend ell,1,a) Fe nando Rubio-Ma cos,2 Adol o del Campo,2 Lou des Mes es,1 and
Jose E. Ga cia3,a)
1 Depa men o Ino ganic and O ganic Chemis y, Uni e si a de Ba celona, 08028 Ba celona, Spain.
2 Depa men o Elec oce amics, Ins i u o de Ce ámica y Vid io (CSIC), 28049 Mad id, Spain
3 Depa men o Physics, Uni e si a Poli ècnica de Ca alunya - Ba celonaTech, 08034 Ba celona, Spain
The (1-x)(Bi0.5Na0.5)TiO3-xBaTiO3 (BNT-BT) sys em has a ac ed a g ea deal o in e es because i
p esen s a mo pho opic phase bounda y (MPB) be ween he hombohed al and e agonal phases
o 0.05<x<0.08. Finding he MPB in BNT-BT sys em o en leads up o ob ain a ma e ial ha shows a
high symme y (pseudo)cubic X- ay di ac ion pa e n. Howe e , his singula composi ion exhibi s
e oelec ici y, which has been explained as a consequence o a ield-induce phase ans o ma ion.
He e, we demons a e ha he s ess elease a e poling, om he i gin s a e o he sample, is a
c ucial phenomenon o ob ain piezoelec ic esponse in MPB BNT-BT. The mechanism behind he
unusual poling-depoling p ocess in piezoce amics exhibi ing high-symme y MPB is elucida ed by
combining X- ay di ac ion measu emen s and ad anced Raman spec oscopy. This unde sco es he
impo ance o pos -poling s ess elease om he i gin s a e as a c i ical ac o in a aining
piezoelec ic esponse in lead- ee piezoce amics wi h high symme y MPB con igu a ions.
Keywo ds: Raman spec oscopy; piezoelec ic ce amics; e oelec ici y; s ess elaxa ion;
mo pho opic phase bounda y
a) Au ho s o whom co espondence should be add essed: [email p o ec ed];
[email p o ec ed]
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Solid solu ions showing mo pho opic phase bounda y (MPB) be ween wo e oelec ic polymo phs
ha e a ac ed a lo o a en ion because he unique p ope ies hese composi ions may exhibi .1-3
Fo ins ance, excep ional p ope ies we e ound in lead zi cona e i ana e (PZT) solid solu ion o
composi ions in which he MPB o ms be ween he e agonal and hombohed al pola phases,4
being hese ma e ials he undispu ed ma ke leade s o piezoelec ic oxides. Howe e ,
en i onmen al conce ns ela ed o lead oxici y ha e led o he de elopmen o lead- ee
piezoelec ic ma e ials, which has ocused he a en ion o many esea che s in he las wen y
yea s.5-7
Since he be e piezoelec ic p ope ies o lead-based piezoelec ic ma e ials was achie ed in
MPB composi ions, he sea ch o lead- ee piezoce amics wi h po en ial high piezoelec ici y has
he e o e been ocused on solid solu ions exhibi ing MPB.8-10 The (1-x)(Bi0.5Na0.5)TiO3-xBaTiO3 (BNT-
BT) sys em has a ac ed a g ea deal o in e es because i p esen s (like he PZT) a MPB be ween
he hombohed al and e agonal phases o 0.05<x<0.08.11-16 Al hough BNT-BT has demons a ed o
own mode a e piezoelec ic esponse,17-19 some in iguing ea u es o his sys em s ill dese e
a en ion because unde s and hem may se e o he design o imp o ed lead- ee piezoelec ic
composi ions.
A delica e balance o polymo phic phases is usually eached a MPB, which has demons a ed o
be s ongly dependen o he ma e ial p ocessing. In he case o BNT-BT, no only a mixed phase o
e agonal and hombohed al polymo phs is ob ained bu also a high symme y, pseudo-cubic phase
may be achie ed o he same nominal composi ion (x=0.06).13,20-22 The unc ional p ope ies depend
on he esul ing phases balance; he e o e, a iable pe o mance is a ained depending on he
p ocessing condi ion. He e, we epo an in-dep h analysis o he local scale s uc u al s ess o BNT-
BT ce amics exhibi ing high symme y MPB. Resul s demons a e ha , in ou speci ic case, he bulk
sample unde goes inc eased s ess compa ed o hei powde ed coun e pa . While his may sugges
a s ess-induced phase phenomenon, i is no he sole o igin o he e o-piezo esponse, gi en he
well- ecognized po en ial con ibu ion o ield-induced e ec s in MPB sys ems.
Polyc ys alline samples comp ising 0.94(Bi0.5Na0.5TiO3)-0.06BaTiO3 (BNT-6BT) we e syn hesized
using con en ional solid-s a e eac ion echniques. De ailed p ocedu es o he p epa a ion o bo h
he powde and ce amics a e p o ided elsewhe e.11 A e sin e ing, a sec ion o he sin e ed sample
was c ushed and annealed, gi ing a powde wi h pa icle size be ween 1 and 5 μm. C ys alline phases
we e analyzed using X- ay di ac ion (XRD) wi h a PANaly ical X'pe P o ins umen . Pa e ns we e
cap u ed wi hin an angula ange o 20 o 80 deg ees (2θ) wi h a s ep size o 0.0334 deg ees and a
du a ion o 100 seconds pe s ep. CuKα adia ion was employed wi h a wo king ol age o 40 kV and
a cu en o 40 mA. The e oelec ic phase dis ibu ion and s ess deg ee o each sample we e
de e mined using a Wi ec alpha-300RA Con ocal Raman Mic oscope. Raman images o he phase
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we e ob ained using a 100x objec i e lens wi h a nume ical ape u e o 0.95 on powde and ce amics
egions o 120 x 120 µm and 70 x 70 µm on he su ace, espec i ely. The Raman images, e ealing
he phase dis ibu ion and s ess deg ee induced by he pola iza ion and depola iza ion p ocesses,
we e cons uc ed om 60 x 60 and 70 x 70 spec a (i.e., 3600 and 4900 spec a pe Raman image,
espec i ely) wi h an acquisi ion ime o 0.5 seconds pe spec um and a lase powe o 20 mW. Gold
elec odes we e spu e ed on pa allel polished aces o he bulk sample o poling, which we e ca ied
ou in a silicone ba h a 25 C unde a dc elec ic ield o 5 kV/mm o 30 min. The pola ized sample
was aged o a week be o e measu emen s we e pe o med in o de o p e en he in luence o aging
p ocesses. Subsequen ly, he sample was annealed by hea ing a a a e o 5 C/min un il eaching
250 C, ollowed by a slow cooling. Be o e ano he week, he sample was pola ized again. The
e oelec ic hys e esis loops o he unpoled sample we e eco ded using a modi ied Sawye -Towe
ci cui a 1 Hz and a oom empe a u e.
XRD is a well-es ablished echnique o e alua e he s uc u al cha ac e is ics o MPB e oelec ic
ma e ials. Fig. 1 displays he XRD pa e ns o BNT-6BT powde (a) and ce amics (b-d). No ably, he
ab ica ion o bulk ce amics inhe en ly in oduces in e nal s ess, p ima ily due o g ain con inemen
du ing he sin e ing p ocess, esul ing in bounda y e ec s. De ailed XRD analysis o he powde ed
sample e eals he p esence o a cubic o pseudocubic phase (Fig. 1a). This is e idenced by examining
he 2θ egions be ween 39.5°<2θ<40.5° and 46°<2θ<47°, whe e a single peak is obse ed in bo h
cases, co esponding o he (111) and (200) e lec ions, espec i ely. In he o me 2θ egion, wo
peaks would be an icipa ed in a hombohed al s uc u e, ep esen ing he (003) and (021) planes,
while a e agonal phase would also mani es a spli ing o he (200) e lec ion. The XRD di ac ion
pa e n o he bulk sample displays an ini ial sepa a ion o he cubic e lec ions on i s p is ine s a e.
This indica es ha he BNT-6BT unde goes a mix u e o hombohed al and e agonal phases upon
ce amics is o med a e sin e ing. Fe oelec ic esponse a his s a e (Fig. 1e) exhibi a ypical P-E
loop wi h expec ed alues o emnan pola iza ion and coe ci e ield.23
The eme gence o he hombohed al and e agonal phases is enla ged a e poling he ce amic,
whe e he peak-spli ing in bo h egions becomes mo e p onounced (Fig. 1c). A simila beha io has
al eady been examined by Daniels e al.,24 whe e a e oelec ic phase (non-cubic) ans o ma ion
can be induced by he applica ion o an elec ic ield. When annealing he pola ized sample, i
becomes appa en ha he s uc u e ends owa ds inc eased symme y compa ed o he non-
pola ized case, as indica ed by he educed isibili y o he di ac ion maxima spli ing, al hough i
does no ully e e o he ini ial (pseudo)cubic s a e obse ed in he powde ed sample. Mo e
impo an ly, a second poling p ocess does no signi ican ly change he XRD pa e n o he unpoled
sample a e annealing (Fig. 1d), unlike wha happened du ing he i s pola iza ion. This sugges s a
s ess- igge ed phase phenomenon, al hough i is no he p ima y sou ce o he e o-piezo
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esponse, aking in o accoun he po en ial con ibu ion induced by he elec ic ield. No e ha he
e oelec ic esponse a e annealing (Fig. 1 ) e eals a ha de P-E loop, indica ed by a no iceable
inc ease in he coe ci e ield along wi h a dec ease in emnan pola iza ion. Fu he mo e, he
pola iza ion does no seem o sa u a e a he same maximum applied elec ic ield, all o which
indica es ha he pola iza ion o ien a ion o his ma e ial in his s a e becomes mo e di icul . I is
wo h no ing ha al hough labo a o y XRD pa e ns p ima ily p o ide in o ma ion om he su ace
o he sample,25 he compa ison o di ac ion pa e ns unde di e en sample condi ions (Fig. 1b-d)
should s ill be conside ed ele an .
Once we ha e con i med ha s ess-induced changes in c ys al s uc u e can be de ec ed using
XRD measu emen s, ou ocus is o demons a e how s ess-induced phase phenomena can al e
domain con igu a ion, hus in luencing he mac oscopic pola iza ion o he c ys al. To assess he
e ec o s ess le els on he ce amic mic os uc u e, expe imen s we e conduc ed using con ocal
Raman mic oscopy (CRM).26 Fig. 2 shows a compa ison be ween powde and ce amic samples using
CRM. In bo h ins ances, a sizable wo k a ea was chosen o assess he homogenei y o he sys ems.
Fig. 2a-b displays images ob ained h ough op ical mic oscopy o he analyzed a eas, while Fig. 2c-d
illus a e he Raman images o he powde and ce amic, espec i ely. No ably, he p ima y
composi ional di e ence be ween he powde and ce amic samples lies in he p esence o a
seconda y phase in he ce amic (highligh ed as blue egions), al hough we can assume his is a
esidual phase on he su ace since i is no de ec ed by XRD. Fig. 2(e– ) depic s he a e age Raman
spec a de i ed om he Raman images shown in Fig. 2(c-d), co esponding o he BNT-BT pe o ski e
phase, ep esen ed by he egions in ed. The decon ol ed spec a is de ailed in Table I. As e idenced,
he p ima y Raman mode (labeled as 2) is cen e ed a app oxima ely in 270 cm⁻¹, and i is employed
o de e mine he ela i e homogenei y and s ess o he samples.
A mo e in iguing explana ion eme ges om he s a is ical analysis o he p ima y Raman mode
o bo h powde and ce amic samples. The powde sample (Fig. 2g) shows a na ow dis ibu ion o
mode 2, indica ing lowe composi ional a ia ion compa ed o he b oade dis ibu ion in he ce amic
sample (Fig. 2h). Ano he no ewo hy obse a ion is he inc ease in he a e age Raman shi o mode
2 in he ce amic sample (271 cm⁻¹) compa ed o he powde ma e ial (267 cm⁻¹). This shi should be
a ibu ed o he dis o ion o he c ys al la ice caused by he eme gence o e oelec ic domains,
which dis ibu e s esses wi hin he g ains. This is co obo a ed by XRD analysis (Fig. 1), indica ing
he appea ance o e oelec ically ac i e phases. Consequen ly, he ce amic in i s p is ine s a e
exhibi s a highe deg ee o s ess.
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TABLE I. Raman modes and hei mode symme y assignmen s in hombohed al BNT ce amics. Acco ding o
he nuclea si e g oup analysis, Raman ac i e phonons o he hombohed al symme y wi h space g oup R3c
(C63 ) a e ep esen ed by ΓRaman = 7A1+6E.
Raman Shi
(cm-1)
Symme y
Labeled
Desc ip ion
~ 150
E (TO)
1
Ne wo k modi ie s o dis o ed
oc ahed al [BiO6] and [NaO6] clus e s
~ 275
A1 (TO2)
2
Pola ib a ion o A1 cha ac e highly
sensi i e o he local pola o de
380
Mode o igina ed om A1 (TO2) mode
o Ti-based pe o ski es.
~ 520
A1 (TO3)
3
Asc ibed o he (O–Ti–O) s e ching
symme ic ib a ions o he
oc ahed al [TiO6] clus e s.
~ 590
4
~ 760
E (LO4)
5
Modes due o he p esence o he
si es wi hin he hombohed al la ice
p e con aining oc ahed al dis o ed
[TiO6] clus e s.
~ 830
A1 (LO3)
6
Simila o he obse a ions in XRD, when he ce amic sample is pola ized and depola ized, a
elaxa ion-s ess phenomenon occu s. Fig. 3 illus a es a pola iza ion-depola iza ion cycle moni o ed
by CRM. Fig. 3a-b shows he a e age Raman spec a and s a is ical analysis o he p ima y Raman
mode o powde ed (Fig. 3a) and ce amic (Fig. 3b) BNT-6BT. Upon pola iza ion (Fig. 3c), he sample
e u ns o i s ini ial s a e, wi h he dis ibu ion o he p ima y Raman mode appea ing a 267 cm⁻¹,
indica ing a elaxa ion phenomenon.26 Howe e , upon depola iza ion (Fig. 3d), he Raman shi
inc eases o 270 cm⁻¹, signi ying an inc ease in s ess. The obse ed Raman shi can be a ibu ed o
changes in he s eng h o he cons an o ce, caused by he a ia ion o he dis ance be ween Ti4+
ions and he coo dina ed oxygen, which al e he e oelec ic o de . Howe e , while in insic la ice
s ain inc eases due o domain alignmen du ing poling, s ess elease is associa ed no only wi h he
in insic p ope ies o he ma e ial bu also wi h ex insic ac o s. Localized mac oscopic (ex insic)
s ess edis ibu ion, pa icula ly a g ain bounda ies, may con ibu e o localized elaxa ion e ec s.27
Upon epola iza ion o he ce amic (Fig. 3e), he sample does no e e o i s elaxed (i.e., i s
pola ized) s a e, sugges ing a endency owa ds inc eased symme y compa ed o he non-pola ized
s a e. Clea ly, i lacks piezoelec ic cha ac e is ics. A emp s o epola ize he ce amic a e u ile,
sugges ing ha he sample ails o elax again, hus emaining de oid o elec omechanical
p ope ies. Essen ially, i is no he s abiliza ion o a pseudocubic phase bu a he he elaxa ion o
s ess du ing he ini ial pola iza ion ha enables he sample o exhibi a o able piezoelec ic
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p ope ies. This sugges s ha he ini ial pola iza ion p ocess in ol es s ess elaxa ion, explaining
why comple e pola iza ion is achie ed almos ins an ly and a oom empe a u e.23
To comp ehensi ely assess he bulk sample, gi en i s small g ain size, we conduc ed Raman
imaging on smalle a eas. This app oach enabled de ailed obse a ion o phase o ien a ion and
sys em ension (i.e., s ess) wi hin each g ain, con ingen upon he pola iza ion angle o he ligh . Fig.
4a displays an op ical image o he sample su ace, while Fig. 4b-c depic s he Raman image and s ess
dis ibu ion de i ed om Raman mode 2 (Table I) o he egion delinea ed by he ed ec angle in
Fig. 4a. To na ow he ocus o he s udy, we isola ed wo g ains labeled as G1 and G2 in Fig. 4b. The
a e age spec a o bo h zones a e depic ed in Fig. 4d, e ealing ha he G1 g ain exhibi s an ele a ed
a e age Raman shi o mode 2 (272.6 cm⁻¹) compa ed o he G2 g ain (265.6 cm⁻¹), a dis inc ion also
e iden in Fig. 4c. This indica es ha a s ess g adien exis s, causing no all g ains o de elop he
same ension. Thus, g ain G1 p esen s a highe deg ee o s ess compa ed o g ain G2, which can be
explained by he eme gence o di e en e oelec ic phases. The mixed phase egion induces a high
deg ee o pola iza ion di ec ions close o oom empe a u e, associa ed wi h pola iza ion di ec ed
along he [001]p and [111]p p imi i e cell edges o he e agonal (T) and he hombohed al (R)
phases, espec i ely.28 The e o e, he R-T phase coexis ence a oom empe a u e p oduces a la ice
de o ma ion associa ed wi h he high deg ee o pola iza ion di ec ions, con ibu ing o he
gene a ion o di e en domain con igu a ions as a consequence o he exis ing s ess g adien in he
sys em.
Since he pola iza ion ec o co ela es di ec ly wi h Raman displacemen ,29 his sugges s a ying
deg ees o pola iza ion ac oss hese g ains. Mo eo e , o asce ain he o ien a ion o he pola iza ion
ec o (o c ys allog aphic o ien a ion), we analyzed he impac o ligh pola iza ion angle on he
Raman modes o he g ains. Fig. 4e illus a es he luc ua ions in he a e age spec um o each
selec ed g ain o pola ized ligh angles (θ) anging om 0° o 90°. No ably, he Raman modes o he
spec um co esponding o he G1 g ain show no dependence on θ a ia ions (nei he in ensi y no
Raman shi unde go modi ica ion), indica ing ha he pola iza ion ec o in g ain G1 lies ou o plane
(as schema ically ep esen ed in panel 4e). Con e sely, he G2 g ain exhibi s a clea dependence on
θ, wi h bo h he in ensi y and shi o he Raman modes e ol ing wi h he lase pola iza ion angle.
Hence, i can be in e ed ha he pola iza ion ec o o g ain G2 lies in he plane, ende ing i
suscep ible o a ia ions wi h θ. As shown in Fig. 4c, s essed g ains wi h ou -o -plane pola iza ion
a e su ounded by dis ended g ains exhibi ing in-plane pola iza ion, being his con igu a ion
un a o able o being eo ien ed as e i ied by he P-E loop in Fig. 1 .
In summa y, we ha e demons a ed ha he MPB BNT-BT can unde go a con o ma ion-induced
phase ans o ma ion om pseudocubic o a non-cubic, e agonal plus hombohed al, polymo phic
phase. The ans o ma ion can be explained in e ms o s ess- elaxa ion cycles whe e samples
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unde go depola iza ion and main ain he e oelec ic phase, ye Raman analysis indica es a
eeme gence o s ess, and he e o e, no piezoelec ic esponse is obse ed. A emp s o epola ize
he sample a e unsuccess ul, sugges ing ha he sample ails o elax again, hus emaining de oid
o elec omechanical p ope ies. Essen ially, i is no he s abiliza ion o a pseudocubic phase bu
a he he elaxa ion o s ess du ing he ini ial pola iza ion ha enables he sample o exhibi
a o able piezoelec ic p ope ies. This implies ha s ess elaxa ion plays a c ucial ole in he ini ial
pola iza ion, explaining he apid achie emen o comple e pola iza ion a oom empe a u e. This
holds pa icula signi icance in he con ex o MPB sys ems, which exhibi high symme y in powde
o m. Hence, i is easonable o sugges inducing a deg ee o phase "ins abili y" du ing p ocessing o
yield a e oelec ic powde phase. This elucida es he no able disc epancies in p ope ies obse ed
among samples appa en ly possessing iden ical composi ions bu a ying le els o symme y in hei
di ac ion pa e ns. The e o e, he elease o s ess pos -poling, s a ing om he p is ine s a e o
he sample, is a c ucial phenomenon o a aining a piezoelec ic esponse in lead- ee piezoce amics
cha ac e ized by high symme y MPB con igu a ions.
Acknowledgemen
This wo k was suppo ed by he Spanish Minis y o Science and Inno a ion, g an numbe s PID2020-
114192RB-C41 and TED2021-130957B-C51 and PID2023-153398OB-I00, unded by
MICIU/AEI/10.13039/501100011033 and he Eu opean Social Fund Plus (FSE+). F. R-M. is indeb ed
o Comunidad de Mad id o he inancial suppo h ough he Doc o ados Indus iales p ojec , g an
numbe IND2020/IND-17375, which is co- inanced by he Eu opean Social Fund. X. V. is a Se a
Hún e Fellow and is g a e ul o he Gene ali a de Ca alunya p ojec 2023 CLIMA 00009 AGAUR.
AUTHOR DECLARATIONS
Con lic o In e es
The au ho s ha e no con lic s o disclose.
Au ho Con ibu ions
Xa ie Vend ell: Fo mal analysis; In es iga ion; Resou ces; Visualiza ion; W i ing – o iginal d a .
Fe nando Rubio-Ma cos: Fo mal analysis; In es iga ion; Valida ion; Visualiza ion; Funding
acquisi ion; W i ing – e iew & edi ing. Adol o del Campo: Fo mal analysis; In es iga ion. Lou des
Mes es: Me hodology; Resou ces; Valida ion. Jose E. Ga cia: Concep ualiza ion; Me hodology;
Visualiza ion; W i ing – e iew & edi ing; Supe ision; P ojec adminis a ion.
DATA AVAILABILITY
The da a ha suppo he indings o his s udy a e a ailable om he co esponding au ho
upon easonable eques .
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REFERENCES
1 B. Noheda, Cu . Opin. Solid. S a e Ma e . Sci. 6, 27–34 (2002).
2 S. T olie -Mckins y, S. Zhang, A. J. Bell, and X. Tan, Annu. Re . Ma e . Res. 48, 191-217 (2018).
3 S. Zhang and F. Li, J. Appl. Phys. 111, 031301 (2012).
4 R. Guo, L. E. C oss, S-E. Pa k, B. Noheda, D. E. Cox, and G. Shi ane, Phys. Re . Le . 84, 5423-5426 (2000).
5 J. Rödel, W. Jo, K. T. P. Sei e , E. An on, T. G anzow, and D. Damjano ic, J. Am. Ce am. Soc. 92, 1153–1177
(2009).
6 J. Rödel, K. G. Webbe , R. Di me , W. Jo, M. Kimu a, and D. Damjano ic, J. Eu . Ce am. Soc. 35, 1659–1681
(2015).
7 T. Zheng, J. Wu, D. Xiao, and J. Zhu, P og. Ma e . Sci. 98, 552–624 (2018).
8 R. Wang, K. Wang, F. Yao, J. Li, F.H. Schade , K.G. Webbe , W. Jo, and J. Rödel, J. Am. Ce am. Soc. 98, 2177–
2182 (2015).
9 J. Wu, D. Xiao, and J. Zhu, Chem. Re . 115, 2559–2595 (2015).
10 X. L , J. Zhu, D. Xiao, X. Zhang, and J. Wu, Chem. Soc. Re . 49, 671-707 (2020).
11 R. Machado, V. B. dos San os, D. A. Ochoa, E. Ce dei as, L. Mes es, and J. E. Ga cía, J. Alloys Compd. 690,
568–574 (2017).
12 G. Pich , J. Töp e , and E. Hennig, J. Eu . Ce am. Soc. 30, 3445–3453 (2010).
13 G. Das Adhika y, G. J. Mule a, and R. Ranjan, Phys. Re . B 108, 224105 (2023).
14 M. Hin e s ein, L. A. Schmi , M. Hoelzel, W. Jo, J. Rödel, H.-J. Kleebe, and M. Ho man, Appl. Phys. Le . 106,
222904 (2015).
15 W. Jo, J. E. Daniels, J. L. Jones, X. Tan, P. A. Thomas, D. Damjano ic, and J. Rödel, J. Appl. Phys. 109, 014110
(2011).
16 P. Singh, A. Sha ma, P. Sha ma, and J. Kol e, Appl. Phys. A 129, 643 (2023).
15 R. Ga g, B. N. Rao, A. Senyshyn, P. S. R. K ishna, and R. Ranjan, Phys. Re . B 88, 014103 (2013).
16 Y. S. Sung, J. M. Kim, J. H. Cho, T. K. Song, M. H. Kim, and T. G. Pa k, Appl. Phys. Le . 96, 202901 (2010).
17 R. R. McQuade and M. R. Dolgos, J. Solid S a e Chem. 242, 140–147 (2016).
18 L. E. Fuen es-Cobas, M. E. Mon e o-Cab e a, J. Plaisie , E. E. Villalobos-Po illo, and L. Pa do, J. Solid S a e
Chem. 316, 123585 (2022).
19 E. Me cadelli, A. Sanson, C. Capiani, L. Cos a, and C. Galassi, P ocess. Appl. Ce am. 3, 73–78 (2009).
22 H. Simons, J. E. Daniels, W. Jo, R. Di me , A. S ude , M. A dee , J. Rödel, and M. Ho man, Appl. Phys. Le .
98, 082901 (2011).
20 H. Guo, C. Ma, X. Liu, and X. Tan, Appl. Phys. Le . 102, 092902 (2013).
21 J. E. Daniels, W. Jo, J. Rödel, and J. L. Jones, Appl. Phys. Le . 95, 032904 (2009).
22 S. Kong, N. Kuma , S. Checchia, C. Cazo la, and J. Daniels, Ad . Func . Ma e . 29, 1900344 (2019).
23 A. P ado-Espinosa, J. Cama go, A. del Campo, F. Rubio-Ma cos, M. Cas o, and L. Ramajo, J. Alloys Compd.
739, 799–805 (2018).
24 F. Rubio-Ma cos, R. López-Juá ez, R. E. Rojas-He nandez, A. del Campo, N. Razo-Pé ez, and J. F. Fe nandez,
ACS Appl. Ma e . In e aces 7, 23080–23088 (2015).
25 F. Rubio-Ma cos, Adol o Del Campo, R. E. Rojas-He nandez, M. O. Ramí ez, R. Pa a, R. U. Ichikawa, L. A.
Ramajo, L. E. Bausá, and J. F. Fe nández, Nanoscale 10, 705-715 (2018).
27 A. Reyes-Mon e o, F. Rubio-Ma cos, L. Pa do, A. Del Campo, R. López-Juá ez, and M.E. Villa ue e-Cas ejón,
J. Ma e . Chem. A 6, 5419 (2018)
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PLEASE CITE THIS ARTICLE AS DOI: 10.1063/5.0238678
9
FIG. 1. X- ay di ac ion (XRD) pa e ns and e oelec ic hys e esis (P-E) loops o BNT-6BT a di e en s a e.
(a) XRD pa e n o he powde showing an appa en cubic phase. (b) The XRD o he p is ine s a e o he
ce amics exhibi s an incipien appea ance o hombohed al and e agonal phases ha is enla ged when he
sample is (c) pola ized. (d) XRD pa e n a e a second poling shows a c ys allog aphic s uc u e mo e
symme ic han he i s pola ized s a e. P-E loops a (e) he p is ine s a e o he ce amics and ( ) a e annealing
and be o e he second poling.
FIG. 2. Fas e alua ion o he s uc u e and homogenei y o bo h he powde and he ce amic samples. (a-b)
Op ical mic og aphs o he powde s and he polished su ace o he ce amic, espec i ely. Scale ba , 20 μm. (c-
d) Raman images showing chemical (in)homogenei y o he powde and he ce amics. The Raman image is
de i ed by summing he o al spec al pixel in ensi y om 100 cm-1 o 1200 cm-1. Scale ba , 10 μm. Blue a eas
in panel d show he seconda y phase loca ion on he bulk BNT-6BT. The black ec angles ma ked as A and B in
he panels (a-b) show he posi ions whe e he XY Raman image a e aken. (e- ) A e age Raman spec a o he
powde and he ce amic samples, espec i ely. Raman spec a a e i ed o he sum o six Lo en zian peaks
co esponding o Raman modes o he BNT-BT pe o ski e phase. The numbe s nex o he ib a ional peaks
ep esen he main a omic mo ions ( o he assignmen o he Raman modes see Table I). (g-h) S a is ical
analysis o he numbe o pixels e sus Raman shi a each pixel co esponding o he Raman mode 2 o he
powde and ce amic samples. An enla gemen o he Raman shi o o 4 cm-1 is e ealed.
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PLEASE CITE THIS ARTICLE AS DOI: 10.1063/5.0238678
