Applied Surface Science 283 (2013) 759–763
Contents lists available at SciVerse ScienceDirect
Applied Surface Science
journal homepage: www.elsevier.com/locate/apsusc
Electrical behaviors of c-axis textured
0.975Bi0.5 Na0.5 TiO3 –0.025BiCoO3 thin films
grown by pulsed laser deposition
Feifei Guo a , Bin Yang a,∗ , Shantao Zhang b,∗∗ , Danqing Liu c , Fengmin Wu a , Dali Wang c ,
Wenwu Cao a,d
a
Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080, China
Department of Materials Science and Engineering & National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
c
School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150080, China
d
Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
b
a r t i c l e
i n f o
Article history:
Received 16 May 2013
Received in revised form 28 June 2013
Accepted 4 July 2013
Available online 12 July 2013
Keywords:
Ferroelectric
Thinfilm
Pulsed laser deposition
Local piezoelectric property
Domain switching
a b s t r a c t
The thin films of 0.975Bi0.5 Na0.5 TiO3 –0.025BiCoO3 (BNT-BC) have been successfully deposited on (1 1 1)
Pt/Ti/SiO2 /Si (1 0 0) substrates by pulse laser deposition and their ferroelectric, dielectric, local piezoelectric properties and temperature dependent leakage current behaviors have been investigated
systematically. X-ray diffraction indicates the films are single phased and c-axis oriented. The thin films
exhibit ferroelectric polarization–electric field (P–E) hysteresis loop with a remnant polarization (Pr ) of
10.0 ␮C/cm2 and an excellent fatigue resistance property up to 5 × 109 switching cycles. The dielectric
constant and dielectric loss are 500 and 0.22 at 1 kHz, respectively. The tunability of the dielectric constant is about 12% at 20 kV/mm. The piezo-phase response hysteresis loop and piezo-amplitude response
butterfly curve are observed by switching spectroscopy mode of piezoelectric force microscope (SS-PFM)
and the piezoelectric coefficient d33 is about 19–63 pm/V, which is comparable to other reports. The dominant leakage current conduction mechanisms are ohmic conduction at low electric field and Schottky
emission at high electric field, respectively. Our results may be helpful for further work on BNT-based
thin films with improved electric properties.
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
Lead-based piezoelectric materials exemplified by Pb(Zr,Ti)O3
(PZT) are widely used for sensors, actuators, and ultrasonic motors
in virtue of their excellent piezoelectric properties [1,2]. However,
lead-pollution and environmental problems caused by the use of
lead-containing piezoelectric materials have become increasingly
serious because of the toxicity of lead oxides. Up to now, a lot of
attention has been paid to lead-free piezoelectric materials due to
increasing environmental and healthy concerns over the widely
used lead-containing materials [2–4]. Among them, Bi0.5 Na0.5 TiO3
(BNT) and its solid solutions have good piezoelectric properties
and thus BNT-based materials are considered to be the potential
candidates for replacing PZT.
In the past two decades, considerable attention has been
focused on investigating the structure and electric properties of
∗ Corresponding author. Tel.: +86 13836127592.
∗∗ Corresponding author. Tel.: +86 13951976481.
E-mail addresses: binyang@hit.edu.cn (B. Yang), stzhang@mail.nju.edu.cn
(S. Zhang).
0169-4332/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.apsusc.2013.07.013
the BNT-based materials in bulk form, detecting that BNT can
form morphotropic phase boundary with other ferroelectrics,
thereby the electric properties can be dramatically improved
[5–8]. Recently, as potential alternative to lead-based thin films
in application, great efforts have been made to the growth and
characterization of BNT-based thin films [9–18]. However, it
should be noticed that the studying on BNT-based thin films is
in an early stage compared with that on BNT-based ceramics.
It is difficult to prepare high quality BNT-based films with high
electric performances and there are limited reports on the local
ferro/piezoelectric properties [11,15,18–23]. Therefore, it is highly
required to seek for high-performance BNT-based thin films.
In our previous work, it has been shown that BiCoO3 doped
BNT ceramics with rhombohedral–tetragonal morphotropic phase
boundary (MPB) components possess excellent electric properties
[24]. However, the ferroelectric, dielectric, leakage current properties and nanoscale characterization of piezoresponse of BNT-BC
thin films are still missing. In this study, we describe the ferroelectric, dielectric, piezoelectric properties and leakage current
behaviors of the 0.975Bi0.5 Na0.5 TiO3 –0.025BiCoO3 , which corresponds to the MPB composition, thin films deposited on (1 1 1)
Pt/Ti/SiO2 /Si (0 0 1) substrates by pulsed laser deposition (PLD).
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F. Guo et al. / Applied Surface Science 283 (2013) 759–763
Fig. 1. XRD patterns of (a) BNT-BC thin films and (b) (1 1 1) Pt/Ti/SiO2 /Si (0 0 1)
substrates.
Fig. 2. (a)Room temperature P–E hysteresis loops; (b)The cross-section SEM micrograph of the BNT-BC thin films.
2. Experimental
The 0.975Bi0.5 Na0.5 TiO3 –0.025BiCoO3 (BNT-BC) ceramics used
as PLD target was prepared by the conventional solid state reaction with 20% excess Bi and Na for compensation of the volatility
during ceramic sintering and thin film depositing. The BNT-BC thin
films were deposited on (1 1 1) Pt/Ti/SiO2 /Si (1 0 0) substrates at
700 ◦ C in a flowing oxygen partial pressure of 25 Pa by PLD using a
krypton fluoride (KrF) excimer laser with a wavelength of 248 nm.
The laser energy and repetition rate were kept at 250 mJ and 5 Hz,
respectively. The distance between the target and the substrate was
about 40 mm. After deposition, the films were in situ annealed at
700 ◦ C under 0.5 atm oxygen pressure for 10 min and then cooled
down to room temperature naturally. In order to investigate the
electrical properties of the thin films, Pt top electrodes of 200 ␮m
in diameter were sputtered using a shadow mask by DC magnetron
sputtering.
The crystal structure of the films was characterized by X-ray
diffraction (XRD) with a Cu K␣ radiation. The ferroelectric properties and leakage current were studied by precision premier II
(Radiant Tech. USA). Dielectric characteristics were measured using
a HP4294A impedance analyzer. Local ferroelectric and piezoelectric properties of thin films were evaluated by piezoelectric force
microscope (PFM, Model MFP-3D, Asylum Research, USA) using
switching spectroscopy mode (SS-PFM). During the SS-PFM measurement, the conductive Pt/Ir coated tip and the conductive Pt
substrate are the top and bottom electrodes, respectively.
3. Results and discussion
The X-ray diffraction (XRD) patterns of BNT-BC thin films and
(1 1 1) Pt/Ti/SiO2 /Si (1 0 0) substrates are shown in Fig. 1(a) and (b)
for comparison, respectively. It can be seen that the thin films are
highly (0 0 1) oriented without detectable second phases. The average thin film thickness is 745 nm, observed from cross-section SEM
measurements shown in Fig. 2(b).
The room temperature polarization–electric field (P–E) hysteresis loops of the BNT-BC thin films are measured under different
elelctric fields at a frequency of 2 kHz, typical results are shown in
Fig. 2(a). As can be seen, the thin films have P–E hysteresis loops,
indicating the ferroelectric nature. The saturation polarization (Ps )
and remnant polarization (Pr ) are 26.4 ␮C/cm2 and 10.0 ␮C/cm2 ,
respectively, while the average coercive field (Ec ) is 7.4 kV/mm.
It should be noticed that the Pr of the films is much lower than
that of BNT-BC ceramics, whereas the Ec is much higher, which
may be attributed to the strong pinning of non-180◦ domain walls
caused by size effect [25]. The difference between the absolute
values of +Ec and −Ec is observed which arises from the imprint
effect: trapped electronic charges near the ferroelectric-electrode
interface can cause internal space charge field [12,25].
Normalized ferroelectric fatigues are measured with triangle
wave with the amplitude of 8 V and the frequency of 100 kHz.
The fatigure behavior is demonstrated in Fig. 3(a). Following the
completion of 5 × 109 switching cycles, the polarization decreases
approximately 10%, indicating the thin films possess a excellent
fatigue resistance, which is further confirmed by the P–E loops
measured before and after fatigue tests, as shown in Fig. 3 (b).
Fig. 4 shows the dielectric constant (εr ) and loss tangent (tanı)
of the BNT-BC thin films as a function of frequency. The εr decreases
monotonously from 500 at 1 kHz to 290 at 1 MHz. On the other
hand, the tanı decreases from 0.22 to 0.12 with the frequency from
1 kHz increasing to 100 kHz and then increases to 0.3 at 1 MHz.
Clearly, the εr and tanı reveal significant frequency dispersion in
the range of 1 kHz–1 MHz. This frequency dispersion in εr and tanı
can be attributed to space charge [26].
Fig. 3. (a) Normalized ferroelectric fatigue as a function of polarization switching cycles; (b) P–E loops measured before and after 5 × 109 switching cycles.
F. Guo et al. / Applied Surface Science 283 (2013) 759–763
Fig. 4. Relative dielectric constant and dielectric loss as a function of frequency.
Fig. 5. Electric field dependence of the relative dielectric constant.
The dielectric constant–electric field (εr –E) curves of the BNT-BC
thin films measured at 100 kHz are shown in Fig. 5. As shown, the
strongly nonlinear behavior is observed in εr –E, indicating typical
ferroelectric capacitors. The reason for change of εr with applied
electric field might be the contribution of domain wall motion
761
Fig. 6. Switching spectroscopy piezoresponse force microscopy (SS-PFM) results
of the BNT-BC thin films, (a) phase–voltage hysteresis loop, (b) amplitude–voltage
butterfly curve.
during the ferroelectric domain switching to dielectric constant.
The dielectric tunability measured with dc bias electric field of
20 kV/mm is calculated to be 12%, which can comparable to that of
pure BNT and BNT-based lead free ferroelectric thin films [12,27].
To confirm the local ferroelectricity and piezoelectricity of
the BNT-BC thin films, polarization switching was examined by
SS-PFM, which is widely used to understand the local switching behavior in ferroelectrics. During the SS-PFM measurement, a
DC bias voltage of ±20 V, corresponding to a field of 27 kV/mm,
was applied through the conductive tip to the BNT-BC thin films,
which is sufficiently large to switch the polarization below the tip
since the coercive field is 7.4 kV/mm. Simultaneously, a small ac
voltage with drive amplitude of 0.5 V and a contact resonance frequency of 290 kHz between the tip and the conductive substrate
was superimposed on the top of DC switching signal, inducing a
local surface vibration due to the piezoelectricity of the thin films.
Fig. 6(a) and (b) show the standard phase–voltage hysteresis loop
and amplitude–voltage butterfly curve, respectively. The phase
response hysteresis loop is symmetric with respect to the applied
Fig. 7. (a) Leakage current density J as a function of electric field E for the BNT-BC thin films measured at different temperatures. Analysis of the leakage current based on (b)
SCLC/ohmic, (c) Schottky, and (d) Poole–Frenkel mechanisms, respectively.
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F. Guo et al. / Applied Surface Science 283 (2013) 759–763
voltage, and extremely sharp polarization switching is observed
in the hysteresis loop with the 180◦ phase reversal, indicating
the existence of 180◦ domains in the BNT-BC thin films and the
nature of ferroelectricity [28,29]. In the amplitude response butterfly curve, the maximum field induced displacement is measured
to be approximately 0.95 nm for BNT-BC thin films. The longitudinal piezoelectric coefficients d33 can be calculate according to
A = d33 Vac Q [29,30], where A is piezoresponse amplitude, Vac is AC
driving voltage applied to the sample through the conductive cantilever tip, and Q is quality factor and typical ranges from 30 to 100
for contact resonances [31]. The d33 is estimated between 19 and
63 pm/V, which can comparable to other reported BNT-based thin
films [11,15,18].
Fig. 7(a) shows the typical current density J of the BNT-BC thin
films as a function of applied electric field E at different temperatures. As shown in Fig. 7(a), the J increases monotonically with
increasing temperature and the J–E characteristics are symmetric
under positive and negative bias voltage at all temperature. To analyze the leakage current mechanism, the study is focused on the
case that the positive bias is applied to the bottom electrode. Based
on the previous reports on lead free thin film, the predominant
conduction mechanisms of Pt/ferroelectric film/Pt capacitor may
be the Ohmic conduction or space charge limited current (SCLC)
conduction at low electric field and Poole–Frenkel (PF) emission
or interface-limited Schottky emission (SE) at high electric field
[32–34]. The Ohmic and SCLC conduction can be expressed by Eqs.
(1 and 2) [32–34], respectively.
between optical-frequency dielectric constants ε∞ ≈ 4.4–6.25 and
static dielectric constant of the BNT films [34]. In Fig. 7(d), the
leakage current characteristics except for at 223k satisfy the PF
equation at high electric field. Using this model, the values of εr
obtained from the slopes are 1.57 × 104 –2.08 × 104 exceeding the
range of relative dielectric constant. Therefore, Schottky emission is
the dominant conduction mechanism in BNT-BC thin films at high
electric field.
4. Conclusion
J = neE,
(1)
In summary, single phase 0.975Bi0.5 Na0.5 TiO3 –0.025BiCoO3
thin films were deposited on (1 1 1) Pt/Ti/SiO2 /Si (1 0 0) substrates
by pulse laser deposition and their ferroelectric, dielectric, local
piezoelectric properties and temperature dependent leakage current behaviors were investigated systematically. The thin films
exhibit ferroelectric P–E hysteresis loops with a Pr of 10 ␮C/cm2
and excellent fatigue resistance. The typical dielectric constant and
dielectric loss are 500 and 0.22 at 1 kHz, respectively, with dielectric
tunability of 12% at 20 kV/mm. The piezo-phase response hysteresis
loop and piezo-amplitude response butterfly curve are observed by
SS-PFM, and the piezoelectric coefficient d33 is about 19–63 pm/V,
which is comparable to other reported BNT-based thin films. The
dominant leakage current conduction mechanisms in the thin films
are Ohmic conduction at low electric field and Schottky emission
at high electric field, respectively. Our results may be helpful for
searching for lead-free ferroelectric thin films with improved electric properties.
J = 9ε0 εr E 2 /8d,
(2)
Acknowledgments
Where n is the density of free electrons, e is the magnitude of
the electronic charge, is the electronic mobility, ε0 is the permittivity of free space, εr is the dielectric constant of thin films and d
is the thickness of the films. The Schottky and Poole-Frenkel (PF)
emissions obey Eq. (3) and Eq. (4) [32–34], respectively.
J = AT 2 exp
J = 0 E exp
ˇS E 1/2 − ˚S
kB T
ˇPF E 1/2 − E1
kB T
(3)
,
(4)
where ˇS = e3 /4ε0 εr
1/2
,
1/2
is the Schottky coefficient, ˇPF =
e3 /ε0 εr
is the Poole-Frenkel coefficient, A is the Richardson
constant, ˚S is the barrier height in the interface, 0 is the sampledependent zero-field conductivity, E1 is the trap ionization energy,
kB is the Boltzmann’s constant, T is the absolute temperature, and
εr is dielectric constant of the films.
To further explore the conduction mechanisms of the BNT-BC
films at low electric, according to the Eqs. (1 and 2), the ln(J) as
functions of ln(E) at different temperature are plotted in Fig. 7(b).
At all measured temperatures, the ln(J)−ln(E) can be fitted well by
the function ln(J) = ˛ln(E)+ˇ. The coefficients ˛ obtained from the
linear fiting are approximately equal to one instead of two implying
that the dominant conductivity mechanism of BNT-BC thin films is
ohmic conduction rather than SCLC at low electric field.
In view of the Eqs. (3 and 4), to investigate the possibilities of
Schottky and Poole-Frenkel mechanism, ln(J/T2 ) versus E1/2 and
ln(J/E) versus E1/2 are shown in Fig. 7(c) and (d), respectively. As
shown in the inset of Fig. 7(c), the date at all temperature fit well to
the Schottky emission at high electric field with slope values falling
in the range of 5.35 × 10−4 to 6.25 × 10−4 . The relative dielectric
constant values can be determined to be 9.98–24.38 by calculating the slope values and ˇS . These values are located on the range
This research was supported by the Key Technologies R&D
Program of China under Grant No. 2013BAI03B06, the National
Nature Science Foundation of China (10704021, 51102062, and
11174127), the Key Scientific and Technological Project of Harbin
(Grant No. 2009AA3BS131), the Postdoctoral Foundation of Heilongjiang Province (Grant No. LBH-Z10147), and the Fundamental
Research Funds for the Central Universities (Grant No. HIT. NSRIF.
2011011).
References
[1] G.H. Haertling, Ferroelectric ceramics: history and technology, J. Am. Ceram.
Soc. 82 (1999) 797–818.
[2] J. Rödel, W. Jo, K.T.P. Seifert, E.-M. Anton, T. Granzow, D. Damjanovic, Perspective on the development of lead-free piezoceramics, J. Am. Ceram. Soc.
92 (2009) 1153–1177.
[3] E. Aksel, J.L. Jons, Advances in lead-free piezoelectric materials for sensors and
actuators, Sensors 10 (2010) 1935–1954.
[4] Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, M.
Nakamura, Lead-free piezoceramics, Nature (London) 432 (2004) 84–87.
[5] A.B. Kounga, S.T. Zhang, W. Jo, T. Granzow, J. Rodel, Morphotropic phase boundary in (1–x)Bi0.5 Na0.5 TiO3 –xK0.5 Na0.5 NbO3 lead-free piezoceramics, Appl. Phys.
Lett. 92 (2008) 222902.
[6] X.X. Wang, X.G. Tang, H.L.W. Chan, Electromechanical and Ferroelectric properties of Bi1/2 Na1/2 TiO3 –Bi1/2 K1/2 TiO3 –BaTiO3 lead-free piezoceramics, Appl.
Phys. Lett. 85 (2004) 91–93.
[7] G.F. Fan, W.Z. Lu, X.H. Wang, F. Liang, Morphotropic phase boundary
and piezoelectric properties of Bi1/2 Na1/2 TiO3 –Bi1/2 K1/2 TiO3 –KNbO3 lead-free
piezoelectric ceramics, Appl. Phys. Lett. 91 (2007) 202908.
[8] S.T. Zhang, F. Yan, B. Yang, Morphotropic phase boundary and electrical properties of (1–x)Bi0.5 Na0.5 TiO3 –xBi(Zn0.5 Ti0.5 )O3 Lead-free piezoceramics, J. Appl.
Phys. 107 (2010) 114110.
[9] M. Abazari, A. Safari, S.S.N. Bharadwaja, S. Trolier-McKinstry, Dielectric and
Piezoelectric Properties of Lead-free (Bi, Na)TiO3 -based Thin Films, Appl. Phys.
Lett. 96 (2010) 082903.
[10] D.Y. Wang, D.M. Lin, K.S. Wong, K.W. Kwok, J.Y. Dai, H.L.W. Chan, Piezoresponse
and Ferroelectric properties of lead-free [Bi0.5 (Na0.7 K0.2 Li0.1 )0.5 ]TiO3 thin films
by pulsed laser deposition, Appl. Phys. Lett. 92 (2008) 222909.
[11] D.Y. Wang, N.Y. Chan, S. Li, S.H. Choy, H.Y. Tian, H.L.W. Chan, Ferroelectric and
Piezoelectric properties in doped lead-free (Bi0.5 Na0.5 )0.94 Ba0.06 TiO3 thin films,
Appl. Phys. Lett. 97 (2010) 212901.
F. Guo et al. / Applied Surface Science 283 (2013) 759–763
[12] J.B. Xu, Y. Liu, R.L. Withers, F. Brink, H. Yang, M. Wang, Ferroelectric and Nonlinear dielectric characteristics of Bi0.5 Na0.5 TiO3 thin films deposited via a
metallorganic decomposition process, J. Appl. Phys. 104 (2008) 116101.
[13] N. Scarisoreanu, F. Craciun, V. Ion, S. Birjega, M. Dinescu, Structural and electrical characterization of lead-free ferroelectric Na1/2 Bi1/2 TiO3 –BaTiO3 thin films
obtained by PLD and RF-PLD, Appl. Surf. Sci. 254 (2007) 1292–1297.
[14] X.J. Zheng, S.H. Dai, X. Feng, T. Zhang, D.Z. Zhang, Y.Q. Gong, Y.Q. Chen, L.
He, Structural and electrical properties of (Na0.85 K0.15 )0.5 Bi0.5 TiO3 thin films
deposited on LaNiO3 and Pt bottom electrodes, Appl. Surf. Sci. 256 (2010)
3316–3320.
[15] Y.Y. Wu, X.H. Wang, C.F. Zhong, L.T. Li, Effect of Mn doping on microstructure
and electrical properties of the (Na0.85 K0.15 )0.5 Bi0.5 TiO3 thin films prepared by
sol–gel method, J. Am. Ceram. Soc. 94 (2011) 3877–3882.
[16] F. Rémondière, A. Wu, P.M. Vilarinho, J.P. Mercurio, Piezoforce microscopy
study of lead-free perovskite Na0.5 Bi0.5 TiO3 thin films, Appl. Phys. Lett. 90
(2007) 152905.
[17] H. Zhou, G.H. Wu, N. Qin, D.H. Bao, Improved electrical properties and strong
red emission of Pr3+ -doped xK0.5 Bi0.5 TiO3 –(1–x)Na0.5 Bi0.5 TiO3 lead-free ferroelectric thin films, J. Am. Ceram. Soc. 95 (2012) 483–486.
[18] T. Yu, K.W. Kwok, H.L.W. Chan, preparation and properties of sol–gel-derived
Bi1/2 Na1/2 TiO3 lead-free ferroelectric thin film, Thin Solid Films 515 (2007)
3563–3566.
[19] D.Z. Zhang, X.J. Zheng, X. Feng, T. Zhang, J. Sun, S.H. Dai, L.J. Gong, Y.Q.
Gong, L. He, Z. Zhu, J. Huang, X. Xu, Ferro-piezoelectric properties of
0.94(Na0.5 Bi0.5 )TiO3 –0.06BaTiO3 thin film prepared by metal–organic decomposition, J. Alloys Compd. 504 (2010) 129–133.
[20] M. Cernea, L. Trupina, C. Dragoi, B.S. Vasile, R. Trusca, Structural and piezoelectric characteristics of BNT-BT0.05 thin films processed by sol–gel technique, J.
Alloys Compd. 515 (2012) 166–170.
[21] C. Dragoi, M. Cernea, L. Trupina, Lead-free ferroelectric BNT-BT0.08
thin films processed by PLD technique, Appl. Surf. Sci. 257 (2011)
9600–9605.
[22] M. Cernea, L. Trupina, C. Dragoi, A.C. Galca, L. Trinca, Structural, optical and
electric properties of BNT-BT0.08 thin films processed by sol–gel technique, J.
Mater. Sci. 47 (2012) 6966–6971.
[23] M. Bousquet, J.R. Duclère, C. Champeaux, A. Boulle, P. Marchet, A. Catherinot,
A. Wu, P.M. Vilarinho, S. Députier, M. Guilloux-Viry, A. Crunteanu, B. Gautier,
D. Albertini, C. Bachelet, Macroscopic and nanoscale electrical properties of
[24]
[25]
[26]
[27]
[28]
[29]
[30]
[31]
[32]
[33]
[34]
763
pulsed laser deposited (1 0 0) epitaxial lead-free Na0.5Bi0.5TiO3 thin films, J.
Appl. Phys. 107 (2010) 034102.
F.F. Guo, B. Yang, S.T. Zhang, X. Liu, L.M. Zheng, Z. Wang, F.M. Wu, D.L.
Wang, W.W. Cao, Morphotropic phase boundary and electric properties in
(1–x)Bi0.5 Na0.5 TiO3 –xBiCoO3 lead-free piezoelectric ceramics, J. Appl. Phys. 111
(2012) 124113.
A.Z. Simões, M.A. Ramírez, A. Ries, J.A. Varela, E. Longo, R. Ramesh, Electromechanical properties of calcium bismuth titanate films: a potential candidate for
lead-free thin-film piezoelectrics, Appl. Phys. Lett. 88 (2006) 072916.
M. Abazari, E.K. Akdoğan, A. Safari, Effect of manganese doping on remnant
polarization and leakage Current in (K0.44 ,Na0.52 ,Li0.04 )(Nb0.84 ,Ta0.10 ,Sb0.06 )O3
epitaxial thin films on SrTiO3 , Appl. Phys. Lett. 92 (2008) 212903.
S.T. Zhang, Y.B. Chen, Z.B. Gu, Optical and electric properties of Bi0.5 Na0.5 TiO3 based thin films grown on Indium-Tin-Oxide-coated glass substrates, Jpn. J.
Appl. Phys. 51 (2012) 011502.
J. Varghese, S. Barth, L. Keeney, R.W. Whatmore, J.D. Holmes, Nanoscale ferroelectric and piezoelectric properties of Sb2 S3 nanowire arrays, Nano Lett. 12
(2011) 868–872.
D. Mohanty, G.S. Chaubey, A. Yourdkhani, S. Adireddy, G. Caruntu, J.B. Wiley,
Synthesis and Piezoelectric Response of Cubic and Spherical LiNbO3 nanocrystals, RSC Adv. 2 (2012) 1913–1916.
L. Lan, S.H. Xie, L. Tan, J.Y. Li, J. Mater, Sol–gel based soft lithography an piezoresponse force microscopy of patterned Pb(Zr0.52 Ti0.48 )O3 microstructures, Sci.
Technol. 26 (2010) 439–444.
M.A. McLachlan, D.W. McComb, M.P. Ryan, A.N. Morozovska, E.A. Eliseev, E.A.
Payzant, S. Jesse, K. Seal, A.P. Baddorf, S.V. Kalinin, Probing Local and Global
ferroelectric phase stability and polarization switching in ordered macroporous
PZT, Adv. Funct. Mater. 21 (2011) 941–947.
M.M. Hejazi, A. Safari, Temperature-dependent leakage current behavior of epitaxial Bi0.5 Na0.5 TiO3 -based thin films made by pulsed laser deposition, J. Appl.
Phys. 110 (2011) 103710.
Z. Wen, X. Shen, J.X. Wu, D. Wu, A. Li, B. Yang, Z. Wang, H.Z. Chen, J.L. Wang,
Temperature-dependent leakage current characteristics of Pr and Mn cosubstituted BiFeO3 thin films, Appl. Phys. Lett. 96 (2010) 202904.
D.Y. Wang, D.M. Lin, K.W. Kwok, N.Y. Chan, J.Y. Dai, S. Li, H.L.W.
Chan, Ferroelectric, piezoelectric, and leakage current properties of
(K0.48 Na0.48 Li0.04 )(Nb0.775 Ta0.225 )O3 thin films grown by pulsed laser deposition,
Appl. Phys. Lett. 98 (2011) 022902.