- Email: [email protected]
High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics
Accepted Manuscript High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics Chenwei Cui, Yongping Pu, Ruike Shi PII:
S0925-8388(18)30107-5
DOI:
10.1016/j.jallcom.2018.01.106
Reference:
JALCOM 44570
To appear in:
Journal of Alloys and Compounds
Received Date: 3 July 2017 Revised Date:
25 September 2017
Accepted Date: 8 January 2018
Please cite this article as: C. Cui, Y. Pu, R. Shi, High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics, Journal of Alloys and Compounds (2018), doi: 10.1016/j.jallcom.2018.01.106. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics Chenwei Cui, Yongping Pu*, Ruike Shi
RI PT
School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi’an 710021, PR China
lead-free
(0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
ceramics
(abbreviated
SC
Abstract
as
M AN U
(0.8-x)ST-0.2NBT-xBT) were prepared by the conventional solid-state sintering method, and their crystal structure, dielectric properties, relaxor behavior and energy-storage property were investigated as a function of BT concentration. X-ray diffraction results reveal a pure perovskite structure with a pseudo-cubic phase. The
TE D
dielectric measurements exhibit a relaxor behavior for all samples and the Tm gradually increases (from -49.67 °C to 67.91 °C) with increasing x. The pinched polarization-electric field (P-E) loops were observed in the samples with x≤0.40 and
EP
the maximum polarization (Pm) increased from 11.37 µC/cm2 to 20.79 µC/cm2 at 8
AC C
kV/mm while x=0.20-0.55. The maximum discharge energy-storage density (Jd) (1.78 J/cm3) is obtained in x=0.35 ceramic with a relatively high Pm (29.19 µC/cm2) under an electric field of 17 kV/mm,which makes (0.8-x)ST-0.2NBT-xBT ceramics may be promising lead-free materials in practical high energy storage application. Keywords: Lead-free; Ceramics; Relaxor behavior; Energy storage density 1. Introduction
ACCEPTED MANUSCRIPT With rapid development of electronic devices, dielectric capacitors are believed to provide effective technical solutions for energy-storage applications because they have the intrinsic fast charged-discharged performance and high power density [1, 2].
RI PT
However, dielectric capacitors based power electronics and pulsed power systems often have large volume and weight. In order to achieve miniaturization, lightweight,
density of dielectric capacitors would be essential.
SC
and integration for energy harvesting and storage capacitors, further improving energy
M AN U
In the modern dielectric capacitor family, antiferroelectrics (AFEs) are receiving increasing attention for energy-storage applications because of their zero remnant polarization (Pr) in idea case and high saturation polarization (Ps) [3-7]. Up to now, almost all reported AFE materials are lead-based materials including PbZrO3 (PZ),
TE D
PbZr1-xTixO3 (PZT) and Pb1-xLax(Zr1-yTiy)1-x/4O3 (PLZT) and many more [8-11]. Although AFEs have relatively high energy storage density, the high toxicity of lead oxide will definitely limit its application and future research.
EP
In order to get an outstanding ceramic material to replace lead-based AFE
AC C
materials, (1-x)SrTiO3-xNa0.5Bi0.5TiO3 (ST-NBT) is the promising new used matrix for energy storage application. On the one hand, ST-NBT system can guarantee a high breakdown strength (BDS) by introducing linear material (ST) with high BDS (~20 kV/mm) [12]. On the other hand, through introducing NBT with excellent ferroelectric properties, the polarization will be greatly improved. Cao [13] found the maximum discharge energy storage density, 0.65 J/cm3, was obtained at 0.7NBT-0.3ST sample, which is low to meet the requirements of practical applications.
ACCEPTED MANUSCRIPT In our previous work [14], we have certified that 0.8ST-0.2NBT ceramic showed a high discharge energy storage density of 1.58 J/cm3 at the applied electric field of 24 kV/mm with a typical relaxor behavior. In order to further improve energy storage
RI PT
density, sometimes, the BDS is overemphasized but polarization, which is another key factor in achieving a high energy storage density, is neglected [15]. BaTiO3 (BT) ceramic plays a key role in the field of energy density capacitors because of its high
SC
polarization and favorable bias stability. Li et al. [16] reported that the
M AN U
0.08Nd(Zn1/2Ti1/2)O3-0.92BaTiO3 (0.08NZT-0.92BT) sample was found to possess the largest energy density about 0.62 J/cm3 at a breakdown field strength 131 kV/cm. Xu et al. [17] reported a large discharge energy density of 1.4 J/cm3 at 14.2 kV/mm in 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15Na0.73Bi0.09NbO3
[(BNT-0.06BT)-NBN]
TE D
ceramic. High dielectric breakdown strength of 300 kV/cm, maximum energy storage density of 1.50 J/cm3 were obtained in fine-crystalline Ba0.4Sr0.6TiO3-MgO composite prepared by spark plasma sintering (SPS) method [18]. Based on the feasibility
EP
analysis above, it is a good try to use BT to form some novel perovskite solid
AC C
solutions for capacity energy storage application. Cao et al. [19] reported that the largest energy density, 0.98 J/cm3 under 90 kV/cm can be obtained in 0.70[0.94NBT-0.06BT]-0.30ST sample, and ST as the doping species to improve the value of Pmax-Pr. Yang et al. [20] studied the energy storage properties of (1-x)ST-x[0.65NBT-0.35BT] ceramics. They found that 0.65NBT-0.35BT could improve the saturated polarization of the ST. However, energy storage density was not
ACCEPTED MANUSCRIPT ideal because the relationship between the host composition and the introduced component did not get the best. In
the
present
work,
(0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
improve energy storage density with relaxor behavior. 2. Experimental procedure (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
((0.8-x)ST-0.2NBT-xBT)
SC
The
RI PT
((0.8-x)ST-0.2NBT-xBT) relaxor ferroelectric ceramics are prepared to further
M AN U
(x=0.20-0.55) ceramics were prepared by a conventional solid-state reaction method using high-purity oxides: Bi2O3 (≥99.0%), SrCO3 (≥99.0%), TiO2 (≥99.0%), Na2CO3 (≥99.0%), BaCO3 (≥99.0%) as raw materials. The first stage of the fabrication was the synthesis of SrTiO3 (ST), Na0.5Bi0.5TiO3 (NBT) and BaTiO3 (BT), respectively.
TE D
According to their stoichiometric formula, raw materials for ST, NBT and BT were mixed in planetary ball mill using zirconia balls for 24 h, respectively. After being milled and dried, the dried slurries for ST, NBT and BT synthesis was calcined at
EP
1150 °C for 3h, 800 °C for 4h and 1150 °C for 3h, respectively. After calcinations, the
AC C
powders were again ball milled separately for 24 h. Afterwards, the suspensions were dried at 85 °C for 12h. The powders were weighed according to the stoichiometric formula of (0.8-x)ST-0.2NBT-xBT and then ball-milled for 24 h, after that the dried calcined powders were pressed into disks by cold isostatic pressing under a pressure of 200 Mpa. They were then sintered in air at 1280-1320 °C for 3 h. Mass densities were measured according to the Archimedes method. The relative densities of all the sintered samples are more than 94%. The sintered ceramics were
ACCEPTED MANUSCRIPT ground into powders for XRD measurement. The crystal structure of crushed ceramics was determined using an X-ray diffractometer (XRD D/max-2200PC, RIGAKU, Japan). The microstructure of the polished and thermal-etched (0.8-x)ST-0.2NBT-xBT
RI PT
ceramics were observed using a scanning electron microscopy (JSM-6700, JEOL Ltd., Tokyo, Japan). For electrical measurements, the sintered samples were polished to obtain smooth and parallel surfaces. Then, a silver paste was painted and fired at
SC
600 °C for 20 min to form the electrode. The frequency dependent permittivity and
frequency
range
from
10
M AN U
dielectric loss were measured by an impedance analyzer (Agilent 4294A) over a Hz
to
1
MHz
at
room
temperature.
The
temperature-dependent dielectric properties were measured using an LCR meter(3532-50, Hioki, Ueda, Japan) and an Agilent 4294A impedance analyzer
TE D
(-180 °C to 200 °C). To determine the polarization versus electric field (P-E) hysteresis loops, the sintered samples were polished to 0.2 mm in thickness and measured by ferroelectric material test system (Aix ACCT Systems GmbH, Aachen,
AC C
10 Hz.
EP
Germany) in a silicone oil bath, using triangular voltage waveforms at a frequency of
3. Results and discussion Fig. 1(a1-a3) shows XRD patterns of pre-synthesized ST, NBT and BT powders.
Fig. 1(b) shows XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics. The patterns suggest the existence of pure perovskite phase with no signs of any secondary phases. This indicates that the expected solid solution ceramics have been formed. Fig. 1(c) and Fig. 1(d) shows enlarged 2θ regions of 39.1-40.1◦ and 45.6-46.7◦ without peak
ACCEPTED MANUSCRIPT splitting indicating the presence of a pseudo-cubic phase in all samples. Moreover, the (111) and (200) diffraction peaks were found to shift to lower angles, suggesting that there is a slight lattice shrinkage. The lattice parameter and the unit cell volume are
RI PT
calculated in Fig. 2. It can be seen that the lattice parameter and the unit cell volume become larger with an increase of the BT content. This is probably due to relatively large ionic radii of Ba2+ compared with Sr2+ and (Na0.5Bi0.5)2+ at A sites (RBa2+=1.61 Å,
M AN U
gradually shift with increasing the x value.
SC
RSr2+=1.44 Å and R(Na0.5Bi0.5)2+=1.38 Å) [21, 22]. It leads to the diffraction peaks
Fig. 3 shows SEM micrographs of the polished and thermally etched surface for the (0.8-x)ST-0.2NBT-xBT ceramics with different x values. The ceramics are densely sintered with low porosity levels. Well defined grains and grain boundaries are
TE D
distinctly visible. In order to easily identify the average grain size of the samples, the average grain size of the (0.8-x)ST-0.2NBT-xBT ceramics was calculated by a linear interception method using an analytical software (Nano Measurer) and the results are
EP
shown in Fig. 3(i). The mean grain size increases from 1.25 µm (x=0.20) to 5.31 µm
AC C
(x=0.55) due to the fact that introduced BT has relatively large grain size. The dielectric properties of the (0.8-x)ST-0.2NBT-xBT ceramics are measured at
room temperature as a function of frequency, in the range from 1 Hz to 100 kHz, as shown in Fig. 4. It is shown that permittivity decreases with the frequency increasing and this change is more and more obvious with increasing x. It is attributed to the Maxwell-Wagner-Sillars interfacial polarization working in the low frequency [23]. Dielectric loss firstly decreases and then increases with the frequency increasing. An
ACCEPTED MANUSCRIPT relatively good frequency stability of permittivity and dielectric loss can be observed at room temperature when x=0.20-0.40, which is beneficial to energy storage applications.
RI PT
The temperature dependence of permittivity and dielectric loss for the (0.8-x)ST-0.2NBT-xBT ceramics at 10 kHz from -180 °C to 200 °C is displayed in Fig. 5(a). It is worth noting that the temperature with the maximum permittivity (Tm) is
SC
significantly increased with increasing x, which can be ascribed to the lattice
M AN U
distortion generated by A-site substitution of Ba2+ ion. In addition, the permittivity at Tm increases firstly and then slightly decreases with increasing x. The Tm of (0.8-x)ST-0.2NBT-xBT ceramics with different values of x is shown in Fig. 5(b). As reported the lattice distortion can be controlled by the chemical pressure generated by
TE D
A-site substitution of ions with different radius, and it is weakened by the large A-site ions substitution thereby leading to high Tm [24, 25]. As the ionic radius of Ba2+ is larger than Sr2+ and (Na0.5Bi0.5)2+, therefore, it is expected to weaken the lattice
temperature
and
frequency
dependence
of
permittivity
(ε′)
of
AC C
The
EP
distortion and enhance the Tm with increasing Ba2+ ionic substitution.
(0.8-x)ST-0.2NBT-xBT ceramics is shown in Fig. 5(c) using the x=0.20, x=0.35 and x=0.55 samples as examples. It can be seen that the maximum permittivity (ε′m) shifts toward higher temperatures with increasing the frequency. Similar phenomenon is also observed in some other perovskite relaxor ferroelectrics [26-28]. The diffuse behavior of the permittivity in Tm can be further described by the degree of diffusivity (γ) [29], which can be obtained by the modified Curie-Weiss law at T＞Tm:
ACCEPTED MANUSCRIPT ଵ ε'
−
ଵ ε'ౣ
=
(்ି்ౣ )ം
(1)
େ
where ε′m is the maximum of the dielectric permittivity at a given frequency, Tm is the corresponding temperature and C refer to the Curie-Weiss constant. The value of
RI PT
critical exponent γ=1 indicates the ceramic exhibits normal ferroelectric behavior and obeys the Curie-Weiss law, while for an ideal relaxor ferroelectric with a large deviation from the Curie-Weiss law γ=2, and γ∈(1, 2) represents an intermediate state,
SC
with a certain degree of diffuseness. Fig. 5(d) shows the variation of γ versus x (the
M AN U
inset is the variation of ln(1/ε-1/εm) versus ln(T-Tm) at 10 kHz). For the present ceramics, the values of γ are in the range of 1.43-1.71, which clearly indicates a diffuseness behavior, which is one of the characteristic properties of relaxor materials. The diffusivity γ corresponds to a very broad relaxation and a higher disorder for
TE D
x=0.45 sample (γ=1.71). This indicates the increase in the degree of lattice disorder due to the incorporation of Ba2+, (Na0.5Bi0.5)2+ and Sr2+ at the A-site. The broadness or diffusiveness occurs mainly due to compositional fluctuation and structural
AC C
structure [30].
EP
disordering in the arrangement of cations in one or more crystallographic site of the
Fig. 6 shows the P-E hysteresis loops for (0.8-x)ST-0.2NBT-xBT ceramics at the
electric field with an amplitude of 8 kV/mm and a frequency of 10 Hz. When x=0.20, a slim P-E loop is observed. When x increased from 0.20 to 0.55, the maximum polarization (Pm) of all samples progressively increased from 11.37 µC/cm2 to 20.79 µC/cm2 at 8 kV/mm and P-E loops are found to become square since the presence of a large amount of the polar phase after BT. In addition, P-E loops are not fully saturated
ACCEPTED MANUSCRIPT at x=0.55, which may be due to the formation of the leakage current, non-ferroelectric passive layer or/and internal field [31]. Fig. 7(a) displays the P-E hysteresis loops of (0.8-x)ST-0.2NBT-xBT ceramics
RI PT
measured at a frequency of 10 Hz and room temperature under the critical electric field. The P-E loops start to become wider from x≥0.45, presumably because the effect of FE phase induced by BT is gradually enhanced. The x=0.40 sample shows a
SC
maximum polarization of 31.89 µC/cm2 at a field of 15 kV/mm at room temperature.
for energy storage performance.
M AN U
It is clearly evident that the x=0.30-0.40 samples have a pinched loop, which is useful
Generally, the discharge energy-storage density (Jd) could be estimated from the
P-E loops, which is calculated by the integral ܬୢ = ౣ ܧdܲ , where E is the applied ౨
TE D
field, P is the polarization, Pm is the maximum polarization, and Pr is the remnant polarization. The charge energy-storage density (Jc) could be calculated by the
integral ܬୡ = ౣ ܧdܲ [32]. As a consequent, The energy-storage efficiency (η)
EP
equals to Jd/Jc. Fig. 7(b)/(c) show the maximum Jd, maximum Jc, and the
AC C
corresponding η of each sample. Due to a relatively high Pm (29.19 µC/cm2), the highest Jd of 1.78 J/cm3 and a high η of 77.06% under an electric field of 17 kV/mm are obtained in the x=0.35 sample. As expected, the x=0.30 sample exhibits the relatively high Jd of 1.76 J/cm3 and the highest η of 77.53%, under an electric field of 17.5 kV/mm. The x=0.40 sample also exhibits the relatively high Jd of 1.70 J/cm3 and a high η of 73.91%, under an electric field of 15 kV/mm. For advanced pulsed power capacitors applications, good electric field endurance
ACCEPTED MANUSCRIPT is an important characteristic. Figure 8 demonstrates the unipolar P-E loops at room temperature at the varied selected electric fields for (0.8-x)ST-0.2NBT-xBT ceramics. The samples were examined at 10 Hz until they went through dielectric breakdown.
RI PT
Both P and E increase with increasing electric fields for all samples. The maximum breakdown electric field is up to 20 kV/mm for x=0.20 sample, indicating that BT contributes to the improvement of P while reducing the breakdown electric field.
SC
The energy storage performance of (0.8-x)ST-0.2NBT-xBT ceramics is usually
M AN U
studied using their P-E hysteresis loops, as shown in Figure 9. The Jd and Jc have the change trends with the increase of the electric field. The Jd and Jc increase with increasing the electric field, while the η decreases with increasing the electric field. The Jc increases from 0.06 J/cm3 to 2.31 J/cm3, and the Jd enhances from 0.04 J/cm3
TE D
to 1.78 J/cm3, respectively, when the electric field increases from 2 kV/mm to 17 kV/mm for x=0.35 ceramic. The largest Jc and Jd (2.31 J/cm3 and 1.78 J/cm3) were obtained for x=0.35 ceramic at 17 kV/mm. A comparison of ferroelectric and energy
EP
storage properties among several lead-free ferroelectric systems was made in Table 1
AC C
[18, 33-38]. It can be seen that the (0.8-x)ST-0.2NBT-xBT (x=0.35) possessed a much higher Jd value together with an acceptable η value. Hence, the sample with x=0.35 in this work is a promising candidate material for high energy storage density capacitors. 4. Conclusions
The solid solutions of (0.8-x)ST-0.2NBT-xBT were prepared by the traditional solid state synthesis technique. Partial substitution Ba for Sr at A-site in the perovskite phase significantly improved dielectric properties, relaxor behavior, energy-storage
ACCEPTED MANUSCRIPT density, and charged-discharged performance of (0.8-x)ST-0.2NBT-xBT ceramics. all samples appear a typical dielectric relaxor behavior and the Tm increases gradually with increasing x. It has the broadest relaxor behavior for (0.8-x)ST-0.2NBT-xBT
RI PT
ceramics when x=0.45. The Pm and Eb of (0.8-x)ST-0.2NBT-xBT ceramics are effectively increased and reduced respectively due to the introduction of BT. Moreover, the highest Jd from P-E loop reached 1.78 J/cm3 under electric field of 17
SC
kV/mm for x=0.35 sample. These results indicate that the (0.8-x)ST-0.2NBT-xBT
M AN U
ceramics with high Jd accompanied with typical dielectric relaxor behavior make them promising materials for modern energy storage technology. Acknowledgments
This research was supported by the National Natural Science Foundation of
TE D
China (51372144,51641207), and the Key Program of Innovative Research Team of Shaanxi Province (2014KCT-06). References
EP
[1] S. Ducharme, An inside-out approach to storing electrostatic energy, ASC Nano 3
AC C
(2009) 2447-2450.
[2] Y. Cao, P.C. Irwin, K. Younsi, The future of nanodielectrics in the electrical power industry, IEEE Trans. Dielectri. Electr. Insul. 11 (2004) 797-807.
[3] A. Chauhan, S. Patel, R. Vaish, C.R. Bowen, Anti-ferroelectric ceramics for high energy density capacitors, Materials 8 (2015) 8009-8031. [4] X. Hao, J. Zhai, L.B. Kong, Z. Xu, A comprehensive review on the progress of lead zirconate-based antiferroelectric materials, Prog. Mater. Sci. 63 (2014) 1-57.
ACCEPTED MANUSCRIPT [5] L. Zhang, S.L. Jiang, Y.K. Zeng, M. Fu, K. Han, Q. Li, Q. Wang, G.Z. Zhang, Y doping and grain size co-effects on the electrical energy storage performance of (Pb0.87Ba0.1La0.02)(Zr0.65Sn0.3Ti0.05)O3 anti-ferroelectric ceramics, Ceram. Int. 40
RI PT
(2014) 5455-5460. [6] Q.F. Zhang, H.F. Tong, J. Chen, Y.M. Lu, T.Q. Yang, X. Yao, Y.B. He, High recoverable energy density over a wide temperature range in Sr modified (Pb,La)
SC
(Zr,Sn,Ti)O3 antiferroelectric ceramics with an orthorhombic phase, Appl. Phys.
M AN U
Lett. 109 (2016) (262901-262904).
[7] H.L. Zhang, X.F. Chen, F. Cao, G.S. Wang, X.L. Dong, Charge-discharge properties of an antiferroelectric ceramics capacitor under different electric fields, J. Am. Ceram. Soc. 93 (2010) 4015-4017.
TE D
[8] F. Jona, G. Shirane, F. Mazzi, X-ray and neutron diffraction study of antiferroelectric lead zirconate, PbZrO3, Phys. Rev. B 105 (1957) 849-856. [9] Y.L. Wang, Z.M. Cheng, Y.R. Sun, Phase transition study of PZT 95/5 ceramics,
EP
Physica B+ C 150 (1988) 168-174.
AC C
[10] X.H. Dai, Z. Xu, J.F. Li, Effects of 1anthanum modification on rhombohedral Pb(Zr1-xTix)O3
ceramics:
part
II.
Relaxor
behavior
versus
enhanced
antiferroelectric stability, J. Mater. Res. 11 (1996) 626-638.
[11] L.L. Zhang, Y.J. Feng, Z. Xu, Electron emission from La-doped Pb(Zr,Sn,Ti)O3 antiferroelectrics by pulse electric field and the relevant physica1 mechanism, Chin. Sci. Bull. 54 (2009) 3489-3493.
ACCEPTED MANUSCRIPT [12] Z. Wang, M. Cao, Z. Yao, Z. Song, G. Li, W. Hu, H. Hao, H. Liu, Dielectric relaxation behavior and energy storage properties in SrTiO3 ceramics with trace amounts of ZrO2 additives, Ceram. Int. 40 (2014) 14127-14132.
RI PT
[13] W.P. Cao, W.L. Li, X.F. Dai, T.D. Zhang, J. Sheng, Y.F. Hou, W.D. Fei, Large electrocaloric response and high energy-storage properties over a broad temperature range in lead-free NBT-ST ceramics, J. Eur. Ceram. Soc. 36 (2016)
SC
593-600.
M AN U
[14] C.W. Cui, Y.P. Pu, Z.Y. Gao, et al., Structure, dielectric and relaxor properties in lead-free ST-NBT ceramics for high energy storage applications, J. Alloys Compd. 711 (2017) 319-326.
[15] B.J.Chu, X. Zhou, K.L. Ren, et al., A dielectric ploymer with high electric energy
TE D
storage and fast discharge speed, Science. 313(2006) 334-336. [16] W.B. Li, D. Zhou, B. He, F. Li, L.X. Pang, S.G. Lu, Structure and dielectric properties of Nd(Zn1/2Ti1/2)O3-BaTiO3 ceramics for energy storage applications, J.
EP
Alloys Compd. 685 (2016) 418-422.
AC C
[17] Q. Xu, M.T. Lanagan, X.C. Huang, J. Xie, L. Zhang, H. Hao, H.X. Liu, Dielectric behavior and impedance spectroscopy in lead-free BNT-BT-NBN perovskite ceramics for energy storage, Ceram. Int. 42 (2016) 9728-9736.
[18] Y.H. Huang, Y.J. Wu, W.J. Qiu, J. Li, X.M. Chen, Enhanced energy storage density of Ba0.4Sr0.6TiO3-MgO composite prepared by spark plasma sintering, J. Eur. Ceram. Soc. 35 (2015) 1469-1476. [19] W.P.Cao, W.L. Li, T.D. Zhang, et al., High-Energy storage density and efficiency
ACCEPTED MANUSCRIPT of (1-x)[0.94NBT-0.06BT]-xST lead-free ceramics, Energy Technol. 3 (2015) 1198-1204. [20] H.B. Yang, F. Yan, G. Zhang, et al., A lead free relaxation and high energy
RI PT
storage efficiency ceramics for energy storage applications, J. Alloys Compd. 710 (2017) 436-445.
[21] Q. Li, J. Wang, Z.Y. Liu, G.Z. Dong, H.Q. Fan, Enhanced energy-storage
SC
properties of BaZrO3-modified 0.80Bi0.5Na0.5TiO3-0.20Bi0.5K0.5TiO3 lead-free
M AN U
ferroelectric ceramics, J. Mater. Sci. 51 (2015) 1153-1160.
[22] X.X. Zhou, C.L. Yuan, Q.N. Li, et al., Energy storage properties and electrical behavior of lead-free (1-x)Ba0.04Bi0.48Na0.48TiO3-xSrZrO3 ceramics, J. Mater. Sci. Mater. El. 27 (2016) 3948-3956.
TE D
[23] H.T. Wang, J.H. Liu, J.W. Zhai, Z.B. Pan, B. Shen, Effects of Sr substitution for Ba on dielectric and energy-storage properties of SrO-BaO-K2O-Nb2O5-SiO2
EP
glass-ceramics, J. Eur. Ceram. Soc. 2017. [24] H. Dong, X.J. Zheng, W. Li, Y.Q. Gong, J.F. Peng, Z. Zhu, The dielectric
AC C
relaxation behavior of (Na0.82K0.18)0.5Bi0.5TiO3 ferroelectric thin film, J. Appl. Phys. 110 (2011) 124109.
[25] X.J. Fan, H. Koinuma, T. Hasegawa, Direct observation of magnetic domains in phase separated Nd0.7Ca0.3MnO3 single crystals, Phys. Rev. B 65 (2002). [26] X. Dai, Z. Xu, J.F. Li, D. Viehland, Effects of lanthanum modification on rhombohedral Pb(Zr1-xTix)O3 ceramics: part I. Transformation from normal to relaxor ferroelectric behaviors, J. Mater. Res. 11 (1996) 618-625.
ACCEPTED MANUSCRIPT [27] W.L. Zhao, R.Z. Zuo, J. Fu, M. Shi, Large strains accompanying field-induced ergodic
phase-polar
ordered
phase
transformations
in
Bi(Mg0.5Ti0.5)O3-PbTiO3-(Bi0.5Na0.5)TiO3 ternary system, J. Eur. Ceram. Soc. 34
RI PT
(2014) 2299-2309. [28] X.L. Chen, J. Chen, D.D. Ma, L. Fang, H.F. Zhou, Thermally stable BaTiO3-Bi(Mg2/3Nb1/3)O3 solid solution with high relative permittivity in a broad
SC
temperature usage range, J. Am. Ceram. Soc. 98 (2015) 804-810.
M AN U
[29] K. Uchino, S. Nomura, Critical exponents of the dielectric constants in diffused-phase-transition crystals, Ferroelectrics 44 (1982) 55-61. [30] T. Badapanda, S. Sarangi, B. Behera, S. Parida, S. Saha, et al., Optical and dielectric study of strontium modified barium zirconium titanate ceramic
TE D
prepared by high energy ball milling, J Alloys Compd. 645 (2015) 586-596. [31] C. Yang, J. Han, X. Cheng, X. Yin, Z. Wang, M. Zhao, C. Wang, Dielectric and ferroelectric properties of (Na0.8K0.2)0.5Bi0.5TiO3 thin films prepared by
EP
metalorganic solution deposition, Appl. Phys. Lett. 87 (2005) 192901.
AC C
[32] X.H. Hao, Y. Wang, L. Zhang, L.W. Zhang, S.L. An, Composition-dependent dielectric and energy-storage properties of (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric
thick films, Appl. Phys. Lett. 102 (2013) 163903.
[33] Z.C. Liu, P.R. Ren, C.B. Long, X. Wang, Y.H.Wan, G.Y. Zhao, Enhanced energy storage properties of NaNbO3 and SrZrO3 modified Bi0.5Na0.5TiO3 based ceramics, J Alloys Compd. DOI:10.1016/j.jallcom.2017.05.162.
ACCEPTED MANUSCRIPT [34] A. Mishra, B. Majumdar, R.Ranjan, A complex lead-free (Na, Bi, Ba)(Ti, Fe)O3 single phase perovskite ceramic with a high energy-density and high discharge-efficiency for solid state capacitor applications, J. Eur. Ceram. Soc. 37
RI PT
(2017) 2379-2384. [35] M.T. Yao, Y.P. Pu, L. Zhang, M. Chen, Enhanced energy storage properties of (1-x)(Bi0.5Na0.5)TiO3-xBa0.85Ca0.15Ti0.9Zr0.1O3 ceramics, Mater. Lett. 35 (2016)
SC
110-113.
M AN U
[36] F. Gao, X.L. Dong, C.L. Mao, et al., Energy-storage properties of 0.89(Bi0.5Na0.5)TiO3-0.06BaTiO3-0.05K0.5Na0.5NbO3 lead-free anti-ferroelectric ceramics, J. Am. Ceram. Soc. 94 (2011) 4382-4386. [37]
D.G.
Zheng,
R.Z.
Enhanced
BiFeO3-BaTiO3
energy
storage
lead-free
relaxor
properties
in
ferroelectric
TE D
La(Mg1/2Ti1/2)O3-modified
Zuo,
ceramics within a wide temperature range, J. Eur. Ceram. Soc. 37 (2017) 413-418.
EP
[38] T. Wang, L. Jin, Y. Tian, L.L. Shu, Q.Y. Hu, X.Y. Wei, Microstructure and
AC C
ferroelectric properties of Nb2O5-modified BiFeO3-BaTiO3 lead-free ceramics for energy storage, Mater. Lett. 137 (2014) 79-81.
ACCEPTED MANUSCRIPT Table 1 Comparison of energy storage properties between (0.8-x)ST-0.2NBT-xBT (x=0.35) ceramics and other lead-free ceramics. E (kV/mm)
Jd (J/cm3)
η (%)
Ref.
NBTBT-SZ-NN
11
0.95
~66
[33]
NBT-BT-BF
8
1.27
~79.7
NBT-BCZT
9.35
0.87
~81
NBT-BT-KNN
5.6
0.59
/
BF-BT-LMT
13
1.66
~82
Ba0.4Sr0.6TiO3+MgO
30
1.50
~88.5
[18]
BF-BT-Nb2O5
9
0.71
/
[38]
ST-NBT-BT
17
RI PT
Composition
[35] [36] [37]
SC
M AN U 1.78
[34]
~77.06
This study
NBT: Na0.5Bi0.5TiO3; ST: SrTiO3; BT: BaTiO3; KNN: K0.5Na0.5NbO3; BF:BiFeO3; BCTZ:
AC C
EP
TE D
Ba0.85Ca0.15Ti0.9Zr0.1O3; LMT: La(Mg0.5Ti0.5)O3;SZ: SrZrO3; NN: NaNbO3
ACCEPTED MANUSCRIPT Fig. 1. XRD patterns of pre-synthesized (a1) ST, (a2) NBT and (a3) BT powders, XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics (b) Full range, the enlarged XRD patterns in the 2 Theta range of (c) 39.1-40.1◦ and (d) 45.6-46.7◦.
RI PT
Fig. 2. Lattice parameters and cell volume as a function of x. Fig. 3. SEM images of the polished and thermally etched surfaces with the measured average grain size distributions. 4.
Frequency
dependence
of
dielectric
properties
for
the
M AN U
(0.8-x)ST-0.2NBT-xBT ceramics.
the
SC
Fig.
Fig. 5. (a) Temperature dependence of permittivity and dielectric loss measured at 10 kHz, (b) the variation of Tm and ɤ as a function of x, (c) permittivity with changing temperature and frequency for a few (0.8-x)ST-0.2NBT-xBT ceramics and (d)
TE D
ln[(1/εr-1/εm)] versus ln(T-Tm) plots.
Fig. 6. P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics measured at 8 kV/mm, 10 Hz. Fig. 7. (a) P-E hysteresis loops measured at 10 Hz of (0.8-x)ST-0.2NBT-xBT ceramics
EP
under critical electric field, (b) Variation in Jd and (c) Variation in Jc and η.
AC C
Fig. 8. Unipolar P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics at room temperature under a few different electric fields. Fig. 9. Discharge energy storage density (Jd), charge energy storage density (Jc) and energy
storage
efficiency
(η)
(0.8-x)ST-0.2NBT-xBT ceramics.
as
a
function
of
electric
field
for
the
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 1. XRD patterns of pre-synthesized (a1) ST, (a2) NBT and (a3) BT powders, XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics (b) Full range, the enlarged XRD patterns
AC C
EP
TE D
in the 2 Theta range of (c) 39.1-40.1◦ and (d) 45.6-46.7◦.
AC C
EP
TE D
M AN U
SC
Fig. 2. Lattice parameters and cell volume as a function of x.
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT (b) x=0.25
5 µm
(c) x=0.30
5 µm (e) x=0.40
5 µm
5 µm
5 µm
M AN U
(h) x=0.55
(g) x=0.50
(f) x=0.45
5 µm
SC
(d) x=0.35
5 µm
RI PT
(a) x=0.20
5 µm
Fig. 3. SEM images of the polished and thermally etched surfaces with the measured
AC C
EP
TE D
average grain size distributions.
4.
Frequency
dependence
of
the
dielectric
EP
TE D
M AN U
(0.8-x)ST-0.2NBT-xBT ceramics.
AC C
properties
SC
Fig.
RI PT
ACCEPTED MANUSCRIPT
for
the
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
TE D
Fig. 5. (a) Temperature dependence of permittivity and dielectric loss measured at 10 kHz, (b) the variation of Tm and ɤ as a function of x, (c) permittivity with changing temperature and frequency for a few (0.8-x)ST-0.2NBT-xBT ceramics and (d)
AC C
EP
ln[(1/εr-1/εm)] versus ln(T-Tm) plots.
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
Fig. 6. P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics measured at 8 kV/mm, 10 Hz.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 7. (a) P-E hysteresis loops measured at 10 Hz of (0.8-x)ST-0.2NBT-xBT ceramics
AC C
EP
TE D
under critical electric field, (b) Variation in Jd and (c) Variation in Jc and η.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 8. Unipolar P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics at room temperature under a few different electric fields.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 9. Discharge energy storage density (Jd), charge energy storage density (Jc) and energy
storage
efficiency
(η)
(0.8-x)ST-0.2NBT-xBT ceramics.
as
a
function
of
electric
field
for
the
ACCEPTED MANUSCRIPT Highlights (1) The system of (0.8-x)ST-0.2NBT-xBT is relatively new. (2) Energy storage properties under different electric fields were studied.
RI PT
(3) Integrated energy storage and relaxation properties were studied at the same time. (4) The maximum discharge energy density of x=0.35 sample reaches up to 1.78
AC C
EP
TE D
M AN U
SC
J/cm3.
S0925-8388(18)30107-5
DOI:
10.1016/j.jallcom.2018.01.106
Reference:
JALCOM 44570
To appear in:
Journal of Alloys and Compounds
Received Date: 3 July 2017 Revised Date:
25 September 2017
Accepted Date: 8 January 2018
Please cite this article as: C. Cui, Y. Pu, R. Shi, High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics, Journal of Alloys and Compounds (2018), doi: 10.1016/j.jallcom.2018.01.106. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT High-energy storage performance in lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 relaxor ferroelectric ceramics Chenwei Cui, Yongping Pu*, Ruike Shi
RI PT
School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi’an 710021, PR China
lead-free
(0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
ceramics
(abbreviated
SC
Abstract
as
M AN U
(0.8-x)ST-0.2NBT-xBT) were prepared by the conventional solid-state sintering method, and their crystal structure, dielectric properties, relaxor behavior and energy-storage property were investigated as a function of BT concentration. X-ray diffraction results reveal a pure perovskite structure with a pseudo-cubic phase. The
TE D
dielectric measurements exhibit a relaxor behavior for all samples and the Tm gradually increases (from -49.67 °C to 67.91 °C) with increasing x. The pinched polarization-electric field (P-E) loops were observed in the samples with x≤0.40 and
EP
the maximum polarization (Pm) increased from 11.37 µC/cm2 to 20.79 µC/cm2 at 8
AC C
kV/mm while x=0.20-0.55. The maximum discharge energy-storage density (Jd) (1.78 J/cm3) is obtained in x=0.35 ceramic with a relatively high Pm (29.19 µC/cm2) under an electric field of 17 kV/mm,which makes (0.8-x)ST-0.2NBT-xBT ceramics may be promising lead-free materials in practical high energy storage application. Keywords: Lead-free; Ceramics; Relaxor behavior; Energy storage density 1. Introduction
ACCEPTED MANUSCRIPT With rapid development of electronic devices, dielectric capacitors are believed to provide effective technical solutions for energy-storage applications because they have the intrinsic fast charged-discharged performance and high power density [1, 2].
RI PT
However, dielectric capacitors based power electronics and pulsed power systems often have large volume and weight. In order to achieve miniaturization, lightweight,
density of dielectric capacitors would be essential.
SC
and integration for energy harvesting and storage capacitors, further improving energy
M AN U
In the modern dielectric capacitor family, antiferroelectrics (AFEs) are receiving increasing attention for energy-storage applications because of their zero remnant polarization (Pr) in idea case and high saturation polarization (Ps) [3-7]. Up to now, almost all reported AFE materials are lead-based materials including PbZrO3 (PZ),
TE D
PbZr1-xTixO3 (PZT) and Pb1-xLax(Zr1-yTiy)1-x/4O3 (PLZT) and many more [8-11]. Although AFEs have relatively high energy storage density, the high toxicity of lead oxide will definitely limit its application and future research.
EP
In order to get an outstanding ceramic material to replace lead-based AFE
AC C
materials, (1-x)SrTiO3-xNa0.5Bi0.5TiO3 (ST-NBT) is the promising new used matrix for energy storage application. On the one hand, ST-NBT system can guarantee a high breakdown strength (BDS) by introducing linear material (ST) with high BDS (~20 kV/mm) [12]. On the other hand, through introducing NBT with excellent ferroelectric properties, the polarization will be greatly improved. Cao [13] found the maximum discharge energy storage density, 0.65 J/cm3, was obtained at 0.7NBT-0.3ST sample, which is low to meet the requirements of practical applications.
ACCEPTED MANUSCRIPT In our previous work [14], we have certified that 0.8ST-0.2NBT ceramic showed a high discharge energy storage density of 1.58 J/cm3 at the applied electric field of 24 kV/mm with a typical relaxor behavior. In order to further improve energy storage
RI PT
density, sometimes, the BDS is overemphasized but polarization, which is another key factor in achieving a high energy storage density, is neglected [15]. BaTiO3 (BT) ceramic plays a key role in the field of energy density capacitors because of its high
SC
polarization and favorable bias stability. Li et al. [16] reported that the
M AN U
0.08Nd(Zn1/2Ti1/2)O3-0.92BaTiO3 (0.08NZT-0.92BT) sample was found to possess the largest energy density about 0.62 J/cm3 at a breakdown field strength 131 kV/cm. Xu et al. [17] reported a large discharge energy density of 1.4 J/cm3 at 14.2 kV/mm in 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15Na0.73Bi0.09NbO3
[(BNT-0.06BT)-NBN]
TE D
ceramic. High dielectric breakdown strength of 300 kV/cm, maximum energy storage density of 1.50 J/cm3 were obtained in fine-crystalline Ba0.4Sr0.6TiO3-MgO composite prepared by spark plasma sintering (SPS) method [18]. Based on the feasibility
EP
analysis above, it is a good try to use BT to form some novel perovskite solid
AC C
solutions for capacity energy storage application. Cao et al. [19] reported that the largest energy density, 0.98 J/cm3 under 90 kV/cm can be obtained in 0.70[0.94NBT-0.06BT]-0.30ST sample, and ST as the doping species to improve the value of Pmax-Pr. Yang et al. [20] studied the energy storage properties of (1-x)ST-x[0.65NBT-0.35BT] ceramics. They found that 0.65NBT-0.35BT could improve the saturated polarization of the ST. However, energy storage density was not
ACCEPTED MANUSCRIPT ideal because the relationship between the host composition and the introduced component did not get the best. In
the
present
work,
(0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
improve energy storage density with relaxor behavior. 2. Experimental procedure (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3
((0.8-x)ST-0.2NBT-xBT)
SC
The
RI PT
((0.8-x)ST-0.2NBT-xBT) relaxor ferroelectric ceramics are prepared to further
M AN U
(x=0.20-0.55) ceramics were prepared by a conventional solid-state reaction method using high-purity oxides: Bi2O3 (≥99.0%), SrCO3 (≥99.0%), TiO2 (≥99.0%), Na2CO3 (≥99.0%), BaCO3 (≥99.0%) as raw materials. The first stage of the fabrication was the synthesis of SrTiO3 (ST), Na0.5Bi0.5TiO3 (NBT) and BaTiO3 (BT), respectively.
TE D
According to their stoichiometric formula, raw materials for ST, NBT and BT were mixed in planetary ball mill using zirconia balls for 24 h, respectively. After being milled and dried, the dried slurries for ST, NBT and BT synthesis was calcined at
EP
1150 °C for 3h, 800 °C for 4h and 1150 °C for 3h, respectively. After calcinations, the
AC C
powders were again ball milled separately for 24 h. Afterwards, the suspensions were dried at 85 °C for 12h. The powders were weighed according to the stoichiometric formula of (0.8-x)ST-0.2NBT-xBT and then ball-milled for 24 h, after that the dried calcined powders were pressed into disks by cold isostatic pressing under a pressure of 200 Mpa. They were then sintered in air at 1280-1320 °C for 3 h. Mass densities were measured according to the Archimedes method. The relative densities of all the sintered samples are more than 94%. The sintered ceramics were
ACCEPTED MANUSCRIPT ground into powders for XRD measurement. The crystal structure of crushed ceramics was determined using an X-ray diffractometer (XRD D/max-2200PC, RIGAKU, Japan). The microstructure of the polished and thermal-etched (0.8-x)ST-0.2NBT-xBT
RI PT
ceramics were observed using a scanning electron microscopy (JSM-6700, JEOL Ltd., Tokyo, Japan). For electrical measurements, the sintered samples were polished to obtain smooth and parallel surfaces. Then, a silver paste was painted and fired at
SC
600 °C for 20 min to form the electrode. The frequency dependent permittivity and
frequency
range
from
10
M AN U
dielectric loss were measured by an impedance analyzer (Agilent 4294A) over a Hz
to
1
MHz
at
room
temperature.
The
temperature-dependent dielectric properties were measured using an LCR meter(3532-50, Hioki, Ueda, Japan) and an Agilent 4294A impedance analyzer
TE D
(-180 °C to 200 °C). To determine the polarization versus electric field (P-E) hysteresis loops, the sintered samples were polished to 0.2 mm in thickness and measured by ferroelectric material test system (Aix ACCT Systems GmbH, Aachen,
AC C
10 Hz.
EP
Germany) in a silicone oil bath, using triangular voltage waveforms at a frequency of
3. Results and discussion Fig. 1(a1-a3) shows XRD patterns of pre-synthesized ST, NBT and BT powders.
Fig. 1(b) shows XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics. The patterns suggest the existence of pure perovskite phase with no signs of any secondary phases. This indicates that the expected solid solution ceramics have been formed. Fig. 1(c) and Fig. 1(d) shows enlarged 2θ regions of 39.1-40.1◦ and 45.6-46.7◦ without peak
ACCEPTED MANUSCRIPT splitting indicating the presence of a pseudo-cubic phase in all samples. Moreover, the (111) and (200) diffraction peaks were found to shift to lower angles, suggesting that there is a slight lattice shrinkage. The lattice parameter and the unit cell volume are
RI PT
calculated in Fig. 2. It can be seen that the lattice parameter and the unit cell volume become larger with an increase of the BT content. This is probably due to relatively large ionic radii of Ba2+ compared with Sr2+ and (Na0.5Bi0.5)2+ at A sites (RBa2+=1.61 Å,
M AN U
gradually shift with increasing the x value.
SC
RSr2+=1.44 Å and R(Na0.5Bi0.5)2+=1.38 Å) [21, 22]. It leads to the diffraction peaks
Fig. 3 shows SEM micrographs of the polished and thermally etched surface for the (0.8-x)ST-0.2NBT-xBT ceramics with different x values. The ceramics are densely sintered with low porosity levels. Well defined grains and grain boundaries are
TE D
distinctly visible. In order to easily identify the average grain size of the samples, the average grain size of the (0.8-x)ST-0.2NBT-xBT ceramics was calculated by a linear interception method using an analytical software (Nano Measurer) and the results are
EP
shown in Fig. 3(i). The mean grain size increases from 1.25 µm (x=0.20) to 5.31 µm
AC C
(x=0.55) due to the fact that introduced BT has relatively large grain size. The dielectric properties of the (0.8-x)ST-0.2NBT-xBT ceramics are measured at
room temperature as a function of frequency, in the range from 1 Hz to 100 kHz, as shown in Fig. 4. It is shown that permittivity decreases with the frequency increasing and this change is more and more obvious with increasing x. It is attributed to the Maxwell-Wagner-Sillars interfacial polarization working in the low frequency [23]. Dielectric loss firstly decreases and then increases with the frequency increasing. An
ACCEPTED MANUSCRIPT relatively good frequency stability of permittivity and dielectric loss can be observed at room temperature when x=0.20-0.40, which is beneficial to energy storage applications.
RI PT
The temperature dependence of permittivity and dielectric loss for the (0.8-x)ST-0.2NBT-xBT ceramics at 10 kHz from -180 °C to 200 °C is displayed in Fig. 5(a). It is worth noting that the temperature with the maximum permittivity (Tm) is
SC
significantly increased with increasing x, which can be ascribed to the lattice
M AN U
distortion generated by A-site substitution of Ba2+ ion. In addition, the permittivity at Tm increases firstly and then slightly decreases with increasing x. The Tm of (0.8-x)ST-0.2NBT-xBT ceramics with different values of x is shown in Fig. 5(b). As reported the lattice distortion can be controlled by the chemical pressure generated by
TE D
A-site substitution of ions with different radius, and it is weakened by the large A-site ions substitution thereby leading to high Tm [24, 25]. As the ionic radius of Ba2+ is larger than Sr2+ and (Na0.5Bi0.5)2+, therefore, it is expected to weaken the lattice
temperature
and
frequency
dependence
of
permittivity
(ε′)
of
AC C
The
EP
distortion and enhance the Tm with increasing Ba2+ ionic substitution.
(0.8-x)ST-0.2NBT-xBT ceramics is shown in Fig. 5(c) using the x=0.20, x=0.35 and x=0.55 samples as examples. It can be seen that the maximum permittivity (ε′m) shifts toward higher temperatures with increasing the frequency. Similar phenomenon is also observed in some other perovskite relaxor ferroelectrics [26-28]. The diffuse behavior of the permittivity in Tm can be further described by the degree of diffusivity (γ) [29], which can be obtained by the modified Curie-Weiss law at T＞Tm:
ACCEPTED MANUSCRIPT ଵ ε'
−
ଵ ε'ౣ
=
(்ି்ౣ )ം
(1)
େ
where ε′m is the maximum of the dielectric permittivity at a given frequency, Tm is the corresponding temperature and C refer to the Curie-Weiss constant. The value of
RI PT
critical exponent γ=1 indicates the ceramic exhibits normal ferroelectric behavior and obeys the Curie-Weiss law, while for an ideal relaxor ferroelectric with a large deviation from the Curie-Weiss law γ=2, and γ∈(1, 2) represents an intermediate state,
SC
with a certain degree of diffuseness. Fig. 5(d) shows the variation of γ versus x (the
M AN U
inset is the variation of ln(1/ε-1/εm) versus ln(T-Tm) at 10 kHz). For the present ceramics, the values of γ are in the range of 1.43-1.71, which clearly indicates a diffuseness behavior, which is one of the characteristic properties of relaxor materials. The diffusivity γ corresponds to a very broad relaxation and a higher disorder for
TE D
x=0.45 sample (γ=1.71). This indicates the increase in the degree of lattice disorder due to the incorporation of Ba2+, (Na0.5Bi0.5)2+ and Sr2+ at the A-site. The broadness or diffusiveness occurs mainly due to compositional fluctuation and structural
AC C
structure [30].
EP
disordering in the arrangement of cations in one or more crystallographic site of the
Fig. 6 shows the P-E hysteresis loops for (0.8-x)ST-0.2NBT-xBT ceramics at the
electric field with an amplitude of 8 kV/mm and a frequency of 10 Hz. When x=0.20, a slim P-E loop is observed. When x increased from 0.20 to 0.55, the maximum polarization (Pm) of all samples progressively increased from 11.37 µC/cm2 to 20.79 µC/cm2 at 8 kV/mm and P-E loops are found to become square since the presence of a large amount of the polar phase after BT. In addition, P-E loops are not fully saturated
ACCEPTED MANUSCRIPT at x=0.55, which may be due to the formation of the leakage current, non-ferroelectric passive layer or/and internal field [31]. Fig. 7(a) displays the P-E hysteresis loops of (0.8-x)ST-0.2NBT-xBT ceramics
RI PT
measured at a frequency of 10 Hz and room temperature under the critical electric field. The P-E loops start to become wider from x≥0.45, presumably because the effect of FE phase induced by BT is gradually enhanced. The x=0.40 sample shows a
SC
maximum polarization of 31.89 µC/cm2 at a field of 15 kV/mm at room temperature.
for energy storage performance.
M AN U
It is clearly evident that the x=0.30-0.40 samples have a pinched loop, which is useful
Generally, the discharge energy-storage density (Jd) could be estimated from the
P-E loops, which is calculated by the integral ܬୢ = ౣ ܧdܲ , where E is the applied ౨
TE D
field, P is the polarization, Pm is the maximum polarization, and Pr is the remnant polarization. The charge energy-storage density (Jc) could be calculated by the
integral ܬୡ = ౣ ܧdܲ [32]. As a consequent, The energy-storage efficiency (η)
EP
equals to Jd/Jc. Fig. 7(b)/(c) show the maximum Jd, maximum Jc, and the
AC C
corresponding η of each sample. Due to a relatively high Pm (29.19 µC/cm2), the highest Jd of 1.78 J/cm3 and a high η of 77.06% under an electric field of 17 kV/mm are obtained in the x=0.35 sample. As expected, the x=0.30 sample exhibits the relatively high Jd of 1.76 J/cm3 and the highest η of 77.53%, under an electric field of 17.5 kV/mm. The x=0.40 sample also exhibits the relatively high Jd of 1.70 J/cm3 and a high η of 73.91%, under an electric field of 15 kV/mm. For advanced pulsed power capacitors applications, good electric field endurance
ACCEPTED MANUSCRIPT is an important characteristic. Figure 8 demonstrates the unipolar P-E loops at room temperature at the varied selected electric fields for (0.8-x)ST-0.2NBT-xBT ceramics. The samples were examined at 10 Hz until they went through dielectric breakdown.
RI PT
Both P and E increase with increasing electric fields for all samples. The maximum breakdown electric field is up to 20 kV/mm for x=0.20 sample, indicating that BT contributes to the improvement of P while reducing the breakdown electric field.
SC
The energy storage performance of (0.8-x)ST-0.2NBT-xBT ceramics is usually
M AN U
studied using their P-E hysteresis loops, as shown in Figure 9. The Jd and Jc have the change trends with the increase of the electric field. The Jd and Jc increase with increasing the electric field, while the η decreases with increasing the electric field. The Jc increases from 0.06 J/cm3 to 2.31 J/cm3, and the Jd enhances from 0.04 J/cm3
TE D
to 1.78 J/cm3, respectively, when the electric field increases from 2 kV/mm to 17 kV/mm for x=0.35 ceramic. The largest Jc and Jd (2.31 J/cm3 and 1.78 J/cm3) were obtained for x=0.35 ceramic at 17 kV/mm. A comparison of ferroelectric and energy
EP
storage properties among several lead-free ferroelectric systems was made in Table 1
AC C
[18, 33-38]. It can be seen that the (0.8-x)ST-0.2NBT-xBT (x=0.35) possessed a much higher Jd value together with an acceptable η value. Hence, the sample with x=0.35 in this work is a promising candidate material for high energy storage density capacitors. 4. Conclusions
The solid solutions of (0.8-x)ST-0.2NBT-xBT were prepared by the traditional solid state synthesis technique. Partial substitution Ba for Sr at A-site in the perovskite phase significantly improved dielectric properties, relaxor behavior, energy-storage
ACCEPTED MANUSCRIPT density, and charged-discharged performance of (0.8-x)ST-0.2NBT-xBT ceramics. all samples appear a typical dielectric relaxor behavior and the Tm increases gradually with increasing x. It has the broadest relaxor behavior for (0.8-x)ST-0.2NBT-xBT
RI PT
ceramics when x=0.45. The Pm and Eb of (0.8-x)ST-0.2NBT-xBT ceramics are effectively increased and reduced respectively due to the introduction of BT. Moreover, the highest Jd from P-E loop reached 1.78 J/cm3 under electric field of 17
SC
kV/mm for x=0.35 sample. These results indicate that the (0.8-x)ST-0.2NBT-xBT
M AN U
ceramics with high Jd accompanied with typical dielectric relaxor behavior make them promising materials for modern energy storage technology. Acknowledgments
This research was supported by the National Natural Science Foundation of
TE D
China (51372144,51641207), and the Key Program of Innovative Research Team of Shaanxi Province (2014KCT-06). References
EP
[1] S. Ducharme, An inside-out approach to storing electrostatic energy, ASC Nano 3
AC C
(2009) 2447-2450.
[2] Y. Cao, P.C. Irwin, K. Younsi, The future of nanodielectrics in the electrical power industry, IEEE Trans. Dielectri. Electr. Insul. 11 (2004) 797-807.
[3] A. Chauhan, S. Patel, R. Vaish, C.R. Bowen, Anti-ferroelectric ceramics for high energy density capacitors, Materials 8 (2015) 8009-8031. [4] X. Hao, J. Zhai, L.B. Kong, Z. Xu, A comprehensive review on the progress of lead zirconate-based antiferroelectric materials, Prog. Mater. Sci. 63 (2014) 1-57.
ACCEPTED MANUSCRIPT [5] L. Zhang, S.L. Jiang, Y.K. Zeng, M. Fu, K. Han, Q. Li, Q. Wang, G.Z. Zhang, Y doping and grain size co-effects on the electrical energy storage performance of (Pb0.87Ba0.1La0.02)(Zr0.65Sn0.3Ti0.05)O3 anti-ferroelectric ceramics, Ceram. Int. 40
RI PT
(2014) 5455-5460. [6] Q.F. Zhang, H.F. Tong, J. Chen, Y.M. Lu, T.Q. Yang, X. Yao, Y.B. He, High recoverable energy density over a wide temperature range in Sr modified (Pb,La)
SC
(Zr,Sn,Ti)O3 antiferroelectric ceramics with an orthorhombic phase, Appl. Phys.
M AN U
Lett. 109 (2016) (262901-262904).
[7] H.L. Zhang, X.F. Chen, F. Cao, G.S. Wang, X.L. Dong, Charge-discharge properties of an antiferroelectric ceramics capacitor under different electric fields, J. Am. Ceram. Soc. 93 (2010) 4015-4017.
TE D
[8] F. Jona, G. Shirane, F. Mazzi, X-ray and neutron diffraction study of antiferroelectric lead zirconate, PbZrO3, Phys. Rev. B 105 (1957) 849-856. [9] Y.L. Wang, Z.M. Cheng, Y.R. Sun, Phase transition study of PZT 95/5 ceramics,
EP
Physica B+ C 150 (1988) 168-174.
AC C
[10] X.H. Dai, Z. Xu, J.F. Li, Effects of 1anthanum modification on rhombohedral Pb(Zr1-xTix)O3
ceramics:
part
II.
Relaxor
behavior
versus
enhanced
antiferroelectric stability, J. Mater. Res. 11 (1996) 626-638.
[11] L.L. Zhang, Y.J. Feng, Z. Xu, Electron emission from La-doped Pb(Zr,Sn,Ti)O3 antiferroelectrics by pulse electric field and the relevant physica1 mechanism, Chin. Sci. Bull. 54 (2009) 3489-3493.
ACCEPTED MANUSCRIPT [12] Z. Wang, M. Cao, Z. Yao, Z. Song, G. Li, W. Hu, H. Hao, H. Liu, Dielectric relaxation behavior and energy storage properties in SrTiO3 ceramics with trace amounts of ZrO2 additives, Ceram. Int. 40 (2014) 14127-14132.
RI PT
[13] W.P. Cao, W.L. Li, X.F. Dai, T.D. Zhang, J. Sheng, Y.F. Hou, W.D. Fei, Large electrocaloric response and high energy-storage properties over a broad temperature range in lead-free NBT-ST ceramics, J. Eur. Ceram. Soc. 36 (2016)
SC
593-600.
M AN U
[14] C.W. Cui, Y.P. Pu, Z.Y. Gao, et al., Structure, dielectric and relaxor properties in lead-free ST-NBT ceramics for high energy storage applications, J. Alloys Compd. 711 (2017) 319-326.
[15] B.J.Chu, X. Zhou, K.L. Ren, et al., A dielectric ploymer with high electric energy
TE D
storage and fast discharge speed, Science. 313(2006) 334-336. [16] W.B. Li, D. Zhou, B. He, F. Li, L.X. Pang, S.G. Lu, Structure and dielectric properties of Nd(Zn1/2Ti1/2)O3-BaTiO3 ceramics for energy storage applications, J.
EP
Alloys Compd. 685 (2016) 418-422.
AC C
[17] Q. Xu, M.T. Lanagan, X.C. Huang, J. Xie, L. Zhang, H. Hao, H.X. Liu, Dielectric behavior and impedance spectroscopy in lead-free BNT-BT-NBN perovskite ceramics for energy storage, Ceram. Int. 42 (2016) 9728-9736.
[18] Y.H. Huang, Y.J. Wu, W.J. Qiu, J. Li, X.M. Chen, Enhanced energy storage density of Ba0.4Sr0.6TiO3-MgO composite prepared by spark plasma sintering, J. Eur. Ceram. Soc. 35 (2015) 1469-1476. [19] W.P.Cao, W.L. Li, T.D. Zhang, et al., High-Energy storage density and efficiency
ACCEPTED MANUSCRIPT of (1-x)[0.94NBT-0.06BT]-xST lead-free ceramics, Energy Technol. 3 (2015) 1198-1204. [20] H.B. Yang, F. Yan, G. Zhang, et al., A lead free relaxation and high energy
RI PT
storage efficiency ceramics for energy storage applications, J. Alloys Compd. 710 (2017) 436-445.
[21] Q. Li, J. Wang, Z.Y. Liu, G.Z. Dong, H.Q. Fan, Enhanced energy-storage
SC
properties of BaZrO3-modified 0.80Bi0.5Na0.5TiO3-0.20Bi0.5K0.5TiO3 lead-free
M AN U
ferroelectric ceramics, J. Mater. Sci. 51 (2015) 1153-1160.
[22] X.X. Zhou, C.L. Yuan, Q.N. Li, et al., Energy storage properties and electrical behavior of lead-free (1-x)Ba0.04Bi0.48Na0.48TiO3-xSrZrO3 ceramics, J. Mater. Sci. Mater. El. 27 (2016) 3948-3956.
TE D
[23] H.T. Wang, J.H. Liu, J.W. Zhai, Z.B. Pan, B. Shen, Effects of Sr substitution for Ba on dielectric and energy-storage properties of SrO-BaO-K2O-Nb2O5-SiO2
EP
glass-ceramics, J. Eur. Ceram. Soc. 2017. [24] H. Dong, X.J. Zheng, W. Li, Y.Q. Gong, J.F. Peng, Z. Zhu, The dielectric
AC C
relaxation behavior of (Na0.82K0.18)0.5Bi0.5TiO3 ferroelectric thin film, J. Appl. Phys. 110 (2011) 124109.
[25] X.J. Fan, H. Koinuma, T. Hasegawa, Direct observation of magnetic domains in phase separated Nd0.7Ca0.3MnO3 single crystals, Phys. Rev. B 65 (2002). [26] X. Dai, Z. Xu, J.F. Li, D. Viehland, Effects of lanthanum modification on rhombohedral Pb(Zr1-xTix)O3 ceramics: part I. Transformation from normal to relaxor ferroelectric behaviors, J. Mater. Res. 11 (1996) 618-625.
ACCEPTED MANUSCRIPT [27] W.L. Zhao, R.Z. Zuo, J. Fu, M. Shi, Large strains accompanying field-induced ergodic
phase-polar
ordered
phase
transformations
in
Bi(Mg0.5Ti0.5)O3-PbTiO3-(Bi0.5Na0.5)TiO3 ternary system, J. Eur. Ceram. Soc. 34
RI PT
(2014) 2299-2309. [28] X.L. Chen, J. Chen, D.D. Ma, L. Fang, H.F. Zhou, Thermally stable BaTiO3-Bi(Mg2/3Nb1/3)O3 solid solution with high relative permittivity in a broad
SC
temperature usage range, J. Am. Ceram. Soc. 98 (2015) 804-810.
M AN U
[29] K. Uchino, S. Nomura, Critical exponents of the dielectric constants in diffused-phase-transition crystals, Ferroelectrics 44 (1982) 55-61. [30] T. Badapanda, S. Sarangi, B. Behera, S. Parida, S. Saha, et al., Optical and dielectric study of strontium modified barium zirconium titanate ceramic
TE D
prepared by high energy ball milling, J Alloys Compd. 645 (2015) 586-596. [31] C. Yang, J. Han, X. Cheng, X. Yin, Z. Wang, M. Zhao, C. Wang, Dielectric and ferroelectric properties of (Na0.8K0.2)0.5Bi0.5TiO3 thin films prepared by
EP
metalorganic solution deposition, Appl. Phys. Lett. 87 (2005) 192901.
AC C
[32] X.H. Hao, Y. Wang, L. Zhang, L.W. Zhang, S.L. An, Composition-dependent dielectric and energy-storage properties of (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric
thick films, Appl. Phys. Lett. 102 (2013) 163903.
[33] Z.C. Liu, P.R. Ren, C.B. Long, X. Wang, Y.H.Wan, G.Y. Zhao, Enhanced energy storage properties of NaNbO3 and SrZrO3 modified Bi0.5Na0.5TiO3 based ceramics, J Alloys Compd. DOI:10.1016/j.jallcom.2017.05.162.
ACCEPTED MANUSCRIPT [34] A. Mishra, B. Majumdar, R.Ranjan, A complex lead-free (Na, Bi, Ba)(Ti, Fe)O3 single phase perovskite ceramic with a high energy-density and high discharge-efficiency for solid state capacitor applications, J. Eur. Ceram. Soc. 37
RI PT
(2017) 2379-2384. [35] M.T. Yao, Y.P. Pu, L. Zhang, M. Chen, Enhanced energy storage properties of (1-x)(Bi0.5Na0.5)TiO3-xBa0.85Ca0.15Ti0.9Zr0.1O3 ceramics, Mater. Lett. 35 (2016)
SC
110-113.
M AN U
[36] F. Gao, X.L. Dong, C.L. Mao, et al., Energy-storage properties of 0.89(Bi0.5Na0.5)TiO3-0.06BaTiO3-0.05K0.5Na0.5NbO3 lead-free anti-ferroelectric ceramics, J. Am. Ceram. Soc. 94 (2011) 4382-4386. [37]
D.G.
Zheng,
R.Z.
Enhanced
BiFeO3-BaTiO3
energy
storage
lead-free
relaxor
properties
in
ferroelectric
TE D
La(Mg1/2Ti1/2)O3-modified
Zuo,
ceramics within a wide temperature range, J. Eur. Ceram. Soc. 37 (2017) 413-418.
EP
[38] T. Wang, L. Jin, Y. Tian, L.L. Shu, Q.Y. Hu, X.Y. Wei, Microstructure and
AC C
ferroelectric properties of Nb2O5-modified BiFeO3-BaTiO3 lead-free ceramics for energy storage, Mater. Lett. 137 (2014) 79-81.
ACCEPTED MANUSCRIPT Table 1 Comparison of energy storage properties between (0.8-x)ST-0.2NBT-xBT (x=0.35) ceramics and other lead-free ceramics. E (kV/mm)
Jd (J/cm3)
η (%)
Ref.
NBTBT-SZ-NN
11
0.95
~66
[33]
NBT-BT-BF
8
1.27
~79.7
NBT-BCZT
9.35
0.87
~81
NBT-BT-KNN
5.6
0.59
/
BF-BT-LMT
13
1.66
~82
Ba0.4Sr0.6TiO3+MgO
30
1.50
~88.5
[18]
BF-BT-Nb2O5
9
0.71
/
[38]
ST-NBT-BT
17
RI PT
Composition
[35] [36] [37]
SC
M AN U 1.78
[34]
~77.06
This study
NBT: Na0.5Bi0.5TiO3; ST: SrTiO3; BT: BaTiO3; KNN: K0.5Na0.5NbO3; BF:BiFeO3; BCTZ:
AC C
EP
TE D
Ba0.85Ca0.15Ti0.9Zr0.1O3; LMT: La(Mg0.5Ti0.5)O3;SZ: SrZrO3; NN: NaNbO3
ACCEPTED MANUSCRIPT Fig. 1. XRD patterns of pre-synthesized (a1) ST, (a2) NBT and (a3) BT powders, XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics (b) Full range, the enlarged XRD patterns in the 2 Theta range of (c) 39.1-40.1◦ and (d) 45.6-46.7◦.
RI PT
Fig. 2. Lattice parameters and cell volume as a function of x. Fig. 3. SEM images of the polished and thermally etched surfaces with the measured average grain size distributions. 4.
Frequency
dependence
of
dielectric
properties
for
the
M AN U
(0.8-x)ST-0.2NBT-xBT ceramics.
the
SC
Fig.
Fig. 5. (a) Temperature dependence of permittivity and dielectric loss measured at 10 kHz, (b) the variation of Tm and ɤ as a function of x, (c) permittivity with changing temperature and frequency for a few (0.8-x)ST-0.2NBT-xBT ceramics and (d)
TE D
ln[(1/εr-1/εm)] versus ln(T-Tm) plots.
Fig. 6. P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics measured at 8 kV/mm, 10 Hz. Fig. 7. (a) P-E hysteresis loops measured at 10 Hz of (0.8-x)ST-0.2NBT-xBT ceramics
EP
under critical electric field, (b) Variation in Jd and (c) Variation in Jc and η.
AC C
Fig. 8. Unipolar P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics at room temperature under a few different electric fields. Fig. 9. Discharge energy storage density (Jd), charge energy storage density (Jc) and energy
storage
efficiency
(η)
(0.8-x)ST-0.2NBT-xBT ceramics.
as
a
function
of
electric
field
for
the
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 1. XRD patterns of pre-synthesized (a1) ST, (a2) NBT and (a3) BT powders, XRD patterns of (0.8-x)ST-0.2NBT-xBT ceramics (b) Full range, the enlarged XRD patterns
AC C
EP
TE D
in the 2 Theta range of (c) 39.1-40.1◦ and (d) 45.6-46.7◦.
AC C
EP
TE D
M AN U
SC
Fig. 2. Lattice parameters and cell volume as a function of x.
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT (b) x=0.25
5 µm
(c) x=0.30
5 µm (e) x=0.40
5 µm
5 µm
5 µm
M AN U
(h) x=0.55
(g) x=0.50
(f) x=0.45
5 µm
SC
(d) x=0.35
5 µm
RI PT
(a) x=0.20
5 µm
Fig. 3. SEM images of the polished and thermally etched surfaces with the measured
AC C
EP
TE D
average grain size distributions.
4.
Frequency
dependence
of
the
dielectric
EP
TE D
M AN U
(0.8-x)ST-0.2NBT-xBT ceramics.
AC C
properties
SC
Fig.
RI PT
ACCEPTED MANUSCRIPT
for
the
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
TE D
Fig. 5. (a) Temperature dependence of permittivity and dielectric loss measured at 10 kHz, (b) the variation of Tm and ɤ as a function of x, (c) permittivity with changing temperature and frequency for a few (0.8-x)ST-0.2NBT-xBT ceramics and (d)
AC C
EP
ln[(1/εr-1/εm)] versus ln(T-Tm) plots.
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
Fig. 6. P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics measured at 8 kV/mm, 10 Hz.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 7. (a) P-E hysteresis loops measured at 10 Hz of (0.8-x)ST-0.2NBT-xBT ceramics
AC C
EP
TE D
under critical electric field, (b) Variation in Jd and (c) Variation in Jc and η.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 8. Unipolar P-E loops of (0.8-x)ST-0.2NBT-xBT ceramics at room temperature under a few different electric fields.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 9. Discharge energy storage density (Jd), charge energy storage density (Jc) and energy
storage
efficiency
(η)
(0.8-x)ST-0.2NBT-xBT ceramics.
as
a
function
of
electric
field
for
the
ACCEPTED MANUSCRIPT Highlights (1) The system of (0.8-x)ST-0.2NBT-xBT is relatively new. (2) Energy storage properties under different electric fields were studied.
RI PT
(3) Integrated energy storage and relaxation properties were studied at the same time. (4) The maximum discharge energy density of x=0.35 sample reaches up to 1.78
AC C
EP
TE D
M AN U
SC
J/cm3.