Scholarly article on topic 'Effect of Fe doping on the structure and electric properties of relaxor type BSPT-PZN piezoelectric ceramics near the morphotropic phase boundary'

Effect of Fe doping on the structure and electric properties of relaxor type BSPT-PZN piezoelectric ceramics near the morphotropic phase boundary Academic research paper on "Materials engineering"

CC BY-NC-ND
0
0
Share paper
Academic journal
Sensors and Actuators A: Physical
OECD Field of science
Keywords
{"Piezoelectric ceramics" / Perovskite / Doping / "Curie temperature" / "Complex system"}

Abstract of research paper on Materials engineering, author of scientific article — Qingwei Liao, Xiaosui Chen, Xiangcheng Chu, Fei Zeng, Dong Guo

Abstract The microstructure and electrical properties of Fe doped ternary complex piezoelectric ceramics 0.35BiScO3-0.6PbTiO3-0.05Pb(Zn1/3Nb2/3)O3-xFe (BSPT-PZN-xFe) with a composition near the morphotropic phase boundary were systematically investigated. The undoped BSPT-PZN showed a relaxor-like behavior. Addition of Fe largely reduced the diffuseness degree and improved the tetragonality. It also reduced the d 33. The dielectric loss and the mechanical quality factor of the samples were, respectively, reduced and increased for about three times. The turning point in most of the parameters implies that the doping characteristics are mainly caused by the increased tetragonality (x <0.4mol%) or by the substitution induced defects (x >0.4mol%). Despite the complicated influence of Fe on the complex high temperature piezoelectric ceramics, it may still be used to significantly improve the ‘hardness’ of similar materials required for high power applications. Direct high temperature d 33 measurements indicated a thermal depolarization temperature (250–260°C) much lower than the peak value temperature (T m ∼410–440°C) in the temperature dependence of dielectric constant. This seems to be a challenge for the BSPT based ternary piezoelectric ceramics.

Academic research paper on topic "Effect of Fe doping on the structure and electric properties of relaxor type BSPT-PZN piezoelectric ceramics near the morphotropic phase boundary"

ELSEVIER

Effect of Fe doping on the structure and electric properties of relaxor type BSPT-PZN piezoelectric ceramics near the morphotropic phase boundary

Qingwei Liaoa, Xiaosui Chena, Xiangcheng Chub, Fei Zengb, Dong Guo3'*

a Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China b Department of Materials Science and Engineering, Tsinghua University, Beijing 100086, China

ABSTRACT

The microstructure and electrical properties of Fe doped ternary complex piezoelectric ceramics 0.35BiScO3-0.6PbTiO3-0.05Pb(Zn1/3Nb2/3 )O3-xFe (BSPT-PZN-xFe) with a composition near the morphotropic phase boundary were systematically investigated. The undoped BSPT-PZN showed a relaxor-like behavior. Addition of Fe largely reduced the diffuseness degree and improved the tetrag-onality. It also reduced the d33. The dielectric loss and the mechanical quality factor of the samples were, respectively, reduced and increased for about three times. The turning point in most of the parameters implies that the doping characteristics are mainly caused by the increased tetragonality (x < 0.4 mol%) or by the substitution induced defects (x > 0.4 mol%). Despite the complicated influence of Fe on the complex high temperature piezoelectric ceramics, it may still be used to significantly improve the 'hardness' of similar materials required for high power applications. Direct high temperature d33 measurements indicated a thermal depolarization temperature (250-260 °C) much lower than the peak value temperature (Tm ~410-440 °C) in the temperature dependence of dielectric constant. This seems to be a challenge for the BSPT based ternary piezoelectric ceramics.

© 2013 Dong Guo. Published by Elsevier B.V. All rights reserved.

Contents lists available at ScienceDirect

Sensors and Actuators A: Physical

journal homepage www.elsevier.com/locate/sna

^Hj CrossMark

ARTICLE INFO

Article history: Received 10 March 2013 Received in revised form 6 July 2013 Accepted 22 July 2013 Available online 31 July 2013

Keywords:

Piezoelectric ceramics

Perovskite

Doping

Curie temperature Complex system

1. Introduction

The rapidly expanding demand for piezoelectric actuators and sensors working under harsh environments (>300 °C), especially in the aerospace and automotive [1-4] industries, has motivated a great deal of research interest for high temperature piezoelectric ceramics. One of the promising high-temperature piezoelectric ceramics that has been intensively studied recently is BiScO3-PbTiO3 (BSPT) [4]. The BSPT system with a composition near the Morphotropic Phase Boundary (MPB, BS/PT = 36/64) shows excellent piezoelectric properties (d33 = 460 pC/N) with still a high Curie temperature (Tc) of about 450 °C [4-6]. The small ionic radius of Bi3+ and the enhanced hybridization between Bi/Pb-6p and O-2p orbitals were reported to be responsible for the large piezoelectric coefficient and the high Tc [7]. A problem of the material is its rather 'soft' property with a high dielectric loss (tan<5^5.0%) and a low mechanical quality factor (Qm ^ 15-50) [6], which lead to a

* Corresponding author. Tel.: +86 10 8254 7679; fax: +86 10 82547677. E-mail addresses: dong.guo@mail.ioa.ac.cn, guodong99@tsinghua.org.cn (D. Guo).

relatively high degree of energy dissipation. Therefore, to decrease the dielectric loss and to increase the Qm of the BSPT type materials seems essential for their practical application, particularly in high power piezoelectric devices. Doping is a widely used route for tailoring the properties of multicomponent ceramics. The intrinsic point defects, the dopant induced defects and their interactions may affect the polarization switching, the domain structure and domain wall stability, and hence, trace amount of doping elements always lead to significant variations in the electrical and mechanical properties. In this respect, various dopants, such as In, Ga, Mn Fe, etc. [8-11], have been tried to modify the performance of BSPT. Among the dopants, Fe was reported to be effective in improving the 'hardness' of the materials. Addition of a new component to BSPT to form a complex ternary or quaternary systems is another way that can substantially modify the performance of the piezoelectric ceramics. The effect may be attributed to the improved sintering process and the formation of more than one MPBs, etc. So far various complex systems such as BSPT-Pb(Mgj/3Nb2/3)O3[12], BSPT-Pb(Mn1/3Nb2/3)O3[13], BSPT-0.05Pb(Zn1/3Nb2/3)O3[14], BSPT-Pb(Mn1/3Sb2/3)O3[15], BSPT-Pb(Mn1/3Ta2/3)O3[16], BSPT-Bi(Mg1/2Ti1/2)O3-BiFeO3[17], etc. have been reported. However, for most of the doped BSPT and BSPT-based complex systems, the

0924-4247/$ - see front matter © 2013 Dong Guo. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sna.2013.07.024

Fig. 1. (a) XRD patterns of the BSPT-PZN-xFe samples with a x in the range of 0 to 1.60 mol%; (b) magnified XRD patterns of the (0 01)/(1 0 0) planes at 29 - 22°; (c) magnified XRD patterns of the (011)/(11 0) planes at 29-31.5°.

reported dielectric loss values are very high, and the available Qm data are rather scattered (though rarely reported). In addition, so far very limited have been tried for modifying the properties of the ternary or quaternary complex systems by doping of metal ions. It is no doubt that the effects of doping are more complicated in the BSPT-based complex systems, because most of the systems (e.g. PMN, PMnN and PZN) introduced are relaxor type materials, whose various dipolar impurities caused by compositional disorder may interact with the dopants, leading to complicated microstructural changes. The samples may show much complicated changes in overall properties but not simple 'soft' (donor) or 'hard' (acceptor) doped characteristics. Therefore, analysis of the property alteration in the doped BSPT based complex system is of both practical and theoretical significance.

In this study, to get a better understanding of the effect of doping on the BSPT-based complex ceramics and to improve the material performance, Fe is selected as a model dopant, and its effects on the electrical properties and microstructure of BSPT-PZN complex system with a composition 0.35BiSc03-0.6PbTi03-0.05Pb(Zn1/3Nb2/3)03 near the MPB boundary were systematically studied.

2. Experimental

The 0.35BiSc03-0.6PbTi03-0.05Pb(Zn1/3Nb2/3)03+ xmol% Fe (hereafter referred to as BSPT-PZN-xFe, x = 0, 0.10, 0.25, 0.40, 0.80, 1.20, 1.60) ceramics were prepared by the columbite precursor method [18]. First, ZnNb206 precursor was synthesized by calcining thoroughly mixed analytically pure Zn0 and Nb205 powders at 1250 °C for 2h. Then stoichiometric ratio of the precursor and analytically pure Bi203, Sc203, Pb0 and Ti02 (with 1 wt% excess amounts of Bi203 and Pb0 for compensating their volatilization during sintering) powders were ball milled for 18 h. Then, the

mixture was calcined (800°C), ground, dried, and pressed into pellets by using polyvinyl alcohol as the binder. After debinding and sintering at 1100°C for 3h in a sealed crucible, ceramic samples with a diameter of about 10 mm and a thickness of about 1.0 mm were obtained. The phase structure were examined by X-ray diffraction (XRD) in the 29 range of 20-60° with a step size of 0.02° with a Bruker D8 advance diffractometer. The microstructure of the fresh fractured surfaces of the samples was examined using a Hitachi S-4800 field emission scanning electron microscopy (FE-SEM). The ceramic pellets for electrical characterization were polished and coated with silver electrodes, and then were poled at ~140 °C for 20min under an electric field of ~3.5kV/mm in a silicone oil bath. The piezoelectric properties were measured after 24 h aging at room temperature. Temperature dependence of dielectric properties were measured using a computer controlled Agilent 4294A (CA, United States) impedance analyzer from room temperature to 600°C. The planar electromechanical coupling factor kp and Qm were derived by the resonance and anti-resonance method. The piezoelectric constant d33 was measured by a quasistatic piezoelectric ZJ-3D d33 meter produced by Institute of Acoustics, Chinese Academy of Sciences. The high temperature d33 was directly measured by a modified ZJ-3DHT type d33 meter equipped with a high temperature sample chamber and a Pt/Rh thermalcouple. The polarization-electric field hysteresis loops were measured with a Precision LC ferroelectric test system (Radiant Technologies, Northford, United States) at room temperature.

3. Results and discussions

The XRD patterns of the undoped BSPT-PZN and BSPT-PZN-xFe samples are shown in Fig. 1 All samples show a perovskite

Fig. 2. Fe content dependence of tetragonality of the BSPT-PZN-xFe samples with a x in the range of 0-1.60 mol%.

main structure. The presence of a small shoulder for the peak at 37.6° is due to the Sc-rich secondary phase. For pure BSPT-PZN, it shows the coexistence of rhombohedral and tetragonal structures. With the increasing Fe content, the (1 0 0), (11 0) and (2 0 0) peaks are getting more splitted into (0 01)/(1 0 0), (01 1)/(l 1 0) and (2 0 0)/(0 0 2) peaks, respectively, indicating a gradual rhom-bohetral to tetragonal phase transition. The splitting can be clearly seen by the magnified (0 01)/(1 0 0) and (01 1)/(11 0) peak patterns shown in Fig. 1(b) and (c), respectively. Tetragonality (e.g. c/a ratio) is an important structure parameter in the perovskite lattice because it is may affect material properties such as spontaneous polarization and Tc. From the XRD profiles, the lattice parameters a and c were derived by Rietveld refinement with pseudo-Voigt function [19] by using Fullprof program, then the tetragonality of the samples is obtained. As can be seen from Fig. 2, with increasing Fe content, the tetragonality of the samples first shows a significant increase and then keeps relatively stable when the Fe content is higher than ~0.25 mol%.

Fig. 3 shows the SEM photographs of the fractured surfaces of various BSPT-PZN-xFe samples. The SEM image of the sample containing 1.2 mol% Fe is very similar to that of the sample containing 0.8 mol% Fe and hence not shown. The pure BSPT-PZN ceramic sample shows a predominantly transgranular morphology. In comparison, addition of Fe in the BSPT-PZN system seems to have induced a largely intergranular fracture surface. While the grain size of the samples seems to show a very slight increasing tendency. It is well known that the piezoelectric response may be dependent on the grain size due to extrinsic contribution from domain wall motion [20]. The piezoelectric coefficient may show the maximum value at an optimum grain size or monotonously decrease with decreasing grain size [20]. Because the grain size shows no obvious change for all the BSPT-PZN-xFe samples illustrated in Fig. 3, their electric performance change (see the following section) should largely attributed to other factors, such as the point defects induced by addition of Fe, which may clam the domain wall motion.

The temperature dependences of dielectric constant and dielectric loss of the BSPT-PZN-xFe samples in the frequency range of 1 kHz-1 MHz are shown in Fig. 4. All samples show evident frequency dispersion, indicating a relaxor-like diffusive phase transformation. As well known, a classical ferroelectric material obeys the Curie-Weiss law: 1/e = (T-Tc)/C' (when T>Tc), where

Tc and C represent Curie-Weiss temperature and Curie constant, respectively. In relaxor-type ferroelectrics, the plot of 1/e versus T obeys a similar relationship but at a higher temperature range, namely when T> TB (TB is a value higher than Tc) [21]. Therefore, a critical exponent y that depicts the degree of diffuseness in relaxor ferroelectrics was proposed [22] based on a modified Curies-Weiss law:

1 = (T - Tm)

In Eq. (1) em and Tm represent the maximum dielectric constant and the corresponding temperature, C" is the Curie-like constant, and y is a value between 1 and 2. When y = 1, Eq. (2) is reduced to the Curie-Weiss relationship valid for normal ferroelectrics. While y = 2 means an ideal relaxor ferroelectric. A typical plot of ln (1/e - 1/em) versus ln(T- Tm) of the data at 100 kHz of a Fe doped (x = 0.10mol%) sample is shown in Fig. 5(a). A diffuseness degree of y = 1.855 can be derived from the rather good linear fitting of the data. Such plots of all other samples also show a good linear fitting. The y values of the samples can then be derived as shown in Fig. 5(c). We can see that addition of Fe largely reduces the diffuseness degree. A y value of 1.993 for the undoped pure BSPT-PZN sample is reduced to 1.307 when the Fe content is increased to 1.6 mol%. Ferroelectric phase transitions may be characterized as either displacive type with a C" of the order of ~105 °C, or orderdisorder type with a C" of the order of C" ~103 °C [23,24], although a material may demonstrate both types of phase transitions. The BSPT-PZN-xFe samples show a C" around 48.45-291.90 x 105 °C (shown in Fig. 5(b)), which is indicative of a predominantly dis-placive type phase transition. This is not unexpected because the spontaneous polarization below Tm in the material results from the displacement of B-site ions. It can be noticed that the dielectric constants at low frequencies increased drastically above the Tm with dopant level >1.2%. Increasing dopant level of Fe may enhance the influence of space charge polarization, which may not follow the external field, leading to largely increased dielectric constants above Tm.

Fig. 6(a) shows the polarization electric field (P-E) hysteresis loops of the BSPT-PZN-xFe samples measured at room temperature. The remnant polarization (Pr) and coercive field (Ec) derived from the loops are shown in Fig. 6(b). The Pr increases slightly from -32.5 |iC/cm2 to a maximum value of-34.1 |iC/cm2 at a Fe content of 0.4 mol%, then it decreases substantially to -15.5 |C/cm2 at a Fe content of -1.6 mol%. The change in Ec is more complicated. The Ec value first decreases, and after a minimum value of 2.33 kV/mm at a Fe content of 0.4mol%, Ec increases to 2.71 kV/mm, then it decreases again. The initial increase in Pr when the Fe content is less than 0.4 mol%, which may be attributed to the oxygen vacancy induced by the small amount of iron dopant, which can facilitate the sintering behavior and hence improve the performance [25], and should be attributed to the relatively large increase in tetrago-nality (see Fig. 2), because a higher tetraganality generally indicates a more stable piezoelectric phase, leading to a higher Pr [26]. While with further increasing of Fe content (x > 0.4 mol%) the tetragonal-ity keeps relatively stable, and the decrease in Pr should be largely caused by the defects caused by the acceptor type substitution of Fe3+ for the B-site ions in the perovskite lattice. In addition, the squareness of the hysteresis loops obviously decreases when the Fe content is above 0.8 mol%. A decreased Pr and an increased Ec are typical characteristics of hard doping. However, a largely decreased Ec is observed when x is above 0.8 mol%. This implies high level of dopant will go to grain boundaries, and will decrease squareness of the PE.

The Fe content dependence of room temperature d33/kp, er/tan1, Qm and Tm of the BSPT-PZN-xFe2O3 ceramic samples is shown in Figs. 7-10, respectively. The x dependence of d33 and kp in Fig. 7

Fig. 3. SEM photographs of fractured surfaces of the BSPT-PZN-xFe samples with a x in the range of 0-1.60 mol%.

shows similar curve shape, and both data show similar change as that of Pr. As explained above, the change may be attributed to the relatively large increase in tetragonality (when x is less than 0.4 mol%) as well as the acceptor substitution induced point defects (when x is more than 0.4mol%). Moreover, it is interesting that most of the data in Figs. 6-9 show a turning point at a x value of ~0.4 mol%, above which dramatic change starts. These imply again that the effect of Fe can be divided into two regimes that are controlled by the tetragonality or by the acceptor substitution induced defects [27,28]. The acceptor doped characteristics of Fe is more clearly demonstrated by the substantial decrease of room temperature e/tan 1 and increase of Qm shown in Figs. 8 and 9, respectively. Particularly, the tan 1 (from 3.71% to 1.36%) and Qm (from 15 to 43) values are changed for about three times by addition of Fe. Also, Tm was increased from 418 to 440 ° C. Considering the ion radius, Fe3+ (0.645 A) may substitute all the B-site ions including Nb5+ (0.640 A), Ti4+ (0.605 A) in the perovskite lattice, then positively charged oxygen vacancies are formed for charge balance. It has been well

accepted that the B site defect may react with the oxygen vacancies to form defect dipoles [28,29]. These dipoles may orient parallel to the spontaneous polarization direction and give rise to an internal bias field, which is believed to be able to pin the domain wall and inhibit polarization switching, leading to decreased Pr and d33. The effect of defect dipole is reflected by the constricted loop of the sample containing 1.60 mol% of Fe shown in Fig. 6(a), as the internal bias always give rise to a constrained loop [30]. The refrained polarization switching may explain the decreased dielectric constant and dielectric loss. Also, the data are at least qualitatively consistent with the electrostrictive coupling relationship [31] d33 = 2e33Q33Pr, where Q33 is the electrostrictive coefficient, and e33 is the dielectric coefficient.

Concerning the underlying driving force for the change in dif-fuseness degree after addition of Fe, some clues may be obtained from the x dependence of tetragonality shown in Fig. 2 and that of the diffuseness degree shown in Fig. 5. By carefully comparing the two figures, we can find that at first both values change largely, and

Fig. 4. Temperature dependence of dielectric constant and dielectric loss in the frequency range of 1 kHz-1 MHz of various BSPT-PZN-xFe samples with a x in the range of 0-1.60 mol%.

Fig. 6. (a) P-E hysteresis loops of the BSPT-PZN-xFe samples with a x in the range of 0-1.60 mol%; (b) Fe content dependence of Pr and Ec derived from the loops.

Fig. 5. (a) The relaxor degree y (100 kHz) of various BSPT-PZN-xFe samples with a x in the range of 0 to 1.60 mol%; (b) The Curie-like constant C"; (c) (The inset of (b)) Linear fit of ln(1/e - 1/em) vs ln(T - Tm) of a typical sample.

when x is higher than about 0.40 mol% they keep relatively stable. In another word, the diffuseness degree change seems to be mainly controlled by the tetragonality, namely, the first regime discussed above. In contrast, the defects caused by the acceptor type substitution may have a minor effect. As a typical relaxor system, the diffusive phase transition of PZN is caused by the symmetry breaking of compositional and structural disorder in the arrangement of non-isovalent Nb5+ and Zn2+ ions on the crystallographically equivalent sites [28,29]. The situation in the complex BSPT-PZN system is similar. Therefore, the results imply that the increased tetragonality as well as the substitution induced defects should have improved the compositional and structural order of the perovskite lattice. We tentatively assume that a more off-center position along the c axis of the B-site ions at a higher tetragonality may make the lattice more stable and improve the structural order [27]. While the defect dipoles may modify the dipolar entities of the polar nan-odomains in the polarizable host BSPT-PZN lattice and improve the compositional order. Both factors may have caused a lower diffuseness degree. More experimental data are required to elucidate the detailed reasons.

The high temperature d33 of two typical samples directly measured by the d33 meter based on the Berlincourt method are shown in Fig. 11. The d33 of the undoped BSPT-PZN sample increases significantly from 470 at room temperature to a maximum of 647 at ~230 °C, then it suddenly decreases to ~22, indicating that thermal depolarization occurs at a temperature much lower than the Tm (418 °C, which is a reflection of transition temperature) measured

Fig. 7. The piezoelectric coefficient d33 and planar coupling factor kp of poled BSPT-PZN-xFe2O3 ceramic samples with a x in the range of 0-1.60 mol%.

from the temperature dependence of dielectric constant shown in Fig. 4. The curve of the BSPT-PZN-1.2Fe sample shows a similar shape with a slightly higher depolarization temperature. Other BSPT-PZN-xFe samples also show similar temperature dependence of d33 and similar Td values around 260 °C.The results indicate that the maximum temperature below which the materials can be used is much lower than the nominal ferroelectric-paraelectric phase transition temperature, and Fe doping has no obvious effect on modifying it. This constitutes a challenge for the ternary piezoelectric ceramics.

Fig. 8. The room temperature dielectric constant er and dielectric loss tan 1(1 kHz) of the BSPT-PZN-xFe2O3 ceramic samples with a x in the range of 0-1.60 mol%.

Fig. 11. The high temperature d33 of BSPT-PZN and BSPT-PZN-1.2Fe2 O3 ceramic samples.

Fig. 9. The Qm of poled BSPT-PZN-xFe2O3 ceramic samples with a x in the range of 0-1.60 mol%.

4. Conclusions

In summary, the structure and electrical properties of the ternary BSPT-PZN-xFe ceramics near the morphotropic phase boundary were systematically investigated. Fe doping largely reduced the diffuseness degree and increased the tetragonality. The tan 1 and the Qm of the samples were, respectively, reduced and increased for about three times, but the d33 was also decreased. The turning point in most of the electric parameters implied that the doping characteristics were mainly caused by the increased tetragonality (x <0.40 mol%) or by the substitution induced defects (x > 0.40 mol%). Despite this complicated influence of Fe on the complex high temperature piezoelectric ceramics, it may still be used to effectively improve the 'hardness' of similar materials required for high power applications. High temperature d33 measurements indicated that thermal depolarization occurred at a temperature much lower than the Tm measured from temperature dependence of dielectric constant. This seems to be a challenge for the BSPT based ternary piezoelectric ceramics.

Acknowledgements

400 I-,-.-,-x-,-.-,-.-,-

0.0 0.4 0.8 1.2 1.6

x (moI%)

Fig. 10. The peak temperature Tm of poled BSPT-PZN-xFe2O3 ceramic samples with a x in the range of 0-1.60 mol%.

This work was supported by the 'Hundred Talents Program' of Chinese Academy of Sciences, the National Key Basic Research Program of China (973 Program, Grant No. 2013CB632900), and the National Science Foundation of China (NSFC No. 11074277). The Authors also thank the Open Foundation of the State Key Laboratory of New Ceramics and Fine Processing of Tsinghua University.

References

[1] A. Moure, A. Castro, L. Pardo, Aurivillius-type ceramics, a class of high temperature piezoelectric materials: drawbacks, advantages and trends, Progress in Solid State Chemistry 37 (2009) 15-39.

[2] F. Gao, R. Hong, J. Liu, Z. Li, L. Cheng, C. Tian, Phase formation and characterization of high curie temperature xBiYbO3-(1-x)PbTiO3 piezoelectric ceramics, Journal of the European Ceramic Society 29 (2009) 1687-1693.

[3] S. Zhang, F. Yu, Piezoelectric materials for high temperature sensors, Journal of the American Ceramic Society 94 (2011) 3153-3170.

[4] R.E. Eitel, C.A. Randall, T.R. Shrout, P.W. Rehrig, W. Hackenberger, S.E. Park, New high temperature morphotropic phase boundary piezoelectrics based on Bi(Me)O3-PbTiO3 ceramics, Japanese Journal of Applied Physics 40 (2001) 5999-6002.

[5] E.E. Richard, A.R. Clive, R.S. Thomas, W.R. Paul, H. Wes, S.E. Park, New high temperature morphotropic phase boundary piezoelectrics based on Bi (Me) O3-PbTiO3 ceramics, Japanese Journal of Applied Physics 40 (2001) 5999-6002.

[6] S. Zhang, E.F. Alberta, R.E. Eitel, C.A. Randall, T.R. Shrout, Elastic, piezoelectric, and dielectric characterizationof modified BiScO3-PbTiO3 ceramics, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 52 (11) (2005) 2131-2139.

[7] J. iniguez, D. Vanderbilt, L. Ballaiche, First-principles study of (BiScO3)1-x-(PbTiO3)x piezoelectric alloys, Physical Review B. 67 (2003) 224107.

[8] Y. Sun, W. Shi, B. Qin, J. Wei, J. Zhu, Preparation and electrical properties of indium doped BiScO3-PbTiO3 piezoelectric ceramics, Electronic components and materials 28 (9) (2009) 34-37.

[9] S. Zhang, D.Y. Jeong, Q. Zhang, T.R. Shrout, Electromechanical and electro-optic properties of xBiScO3 -yBiGaO3 -(1 -x-y )PbTiO3 single crystals, Journal of Crystal Growth 247 (2003) 131-136.

[10] Z. Yao, H. Liu, M. Cao, H. Zhu, Effects ofMn doping on the structure and electrical properties of high-temperature BiScO3-PbTiO3-Pb(Zn1/3Nb2/3)O3 piezoelectric ceramics, Materials Research Bulletin 32 (6) (2011) 1027-1033.

[11] P. Winotai, N. Udomkanb, S. Meejoo, Piezoelectric properties ofFe2O3-doped (1-x)BiScO3-xPbTiO3 ceramics, Sensors and Actuators A 122 (2005) 257-263.

[12] C.J. Stringer, N.J. Donnelly, T.R. Shrout, C.A. Randall, E.F. Alberta, W.S. Hack-enberger, Dielectric characteristics ofperovskite-structured high-temperature relaxor ferroelectrics: the BiScO3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ternary system, Journal ofthe American Ceramic Society 91 (2008) 1781-1787.

[13] J. Ryu, S. Priya, C. Sakaki, K. Uchino, High power piezoelectric characteristics of BiScO3-PbTiO3-Pb(Mn1/3Nb2/3)O3, Japanese Journal of Applied Physics 41 (2002) 6040-6044.

[14] Z. Yao, H. Liu, H. Hao, M. Cao, Structure, electrical properties, and depoling mechanism of BiScO3-PbTiO3-Pb(Zn1/3Nb2/3)O3 high-temperature piezoelectric ceramics, Journal of Applied Physics 109 (2011) 014105.

[15] W. Qian, Y. Yang, Y. Wang, B. Wang, L. Liu, Structure and electrical properties of0.07Pb(Mn1/3Sb2/3)O3-(0.93-x)BiScO3-xPbTiO3 piezoelectrics ceramics, in: Symposium on Piezoelectricity, Acoustic Waves and Device Applications (SPAWDA), 2011, pp. 293-297.

[16] W. Guo, A. Ding, H. Wang, Structure and piezoelectric characteristics of (0.90-x)BiScC)3 -xPbTiO3-0.10Pb(Mn1/3Ta2/3 )O3 system, Journal ofthe Ceramic Society of Japan 117 (8) (2009) 891-894.

[17] T. Sebastian, I. Sterianou, D.C. Sinclair, High temperature piezoelectric ceramics in the Bi(Mg1/2Ti1/2)O3-BiFeO3-BiScO3-PbTiO3 system, Journal ofElectroceram-ics 25 (2010) 130-134.

[18] S.L. Swartz, T.R. Shrout, Fabrication of perovskite lead magnesium niobate original, Materials Research Bulletin 17 (1982) 1245-1250.

[19] H.M. Rietveld, A profile refinement method fornuclearand magnetic structures, Journal of Applied Crystallography 2 (1969) 65-71.

[20] P. Zheng, J.L. Zhang, Y.Q. Tan, C.L. Wang, Grain-size effects on dielectric and piezoelectric properties of poled BaTiO3 ceramics, Acta Materialia 60 (2012) 5022-5030.

[21] G. Burns, F.H. Dacol, Crystalline ferroelectrics with glassy polarization behavior, Physical Review B 28 (1983) 2527-2530.

[22] T.R. Shrout, L.E. Cross, Ferroelectric properties of tungsten bronze lead barium niobate single-crystals, Ferroelectrics Letters 44 (1983) 325-330.

[23] B.E. Nakamura, T. Mitsui, J. Furuichi, A note on the classification of ferroelectrics, Journal ofthe Physical Society ofJapan 18 (1963) 1477-1481.

[24] J.B. Lim, S. Zhang, T.R. Shrout, Relaxor behavior of piezoelectric Pb(Yb1/2Nb1/2)O3-PbTiO3 ceramics sintered at low temperature, Journal of Electroceramics 26 (2011) 68-73.

[25] S. Zhang, R. Xia, L. Lebrun, D. Anderson, T.R. Shrout, Piezoelectric materials for high power, high temperature applications, Materials Letters 59 (2005) 3471-3475.

[26] S. Wada, T. Hoshina, H. Yasuno, S.M. Nam, H. Kakemoto, Tsurumi, M. Yashima, Size dependence of dielectric properties for nm-sized barium titanate crystallites and its origin, Journal of the Korean Physical Society 46 (1) (2005) 303-307.

[27] J. Fu, R. Zuo, X. Wang, L. Li, Phase transition characteristics and piezoelectric properties of compositionally optimized alkaline niobate based ceramics, Journal of Alloys and Compounds 486 (2009) 790-794.

[28] E. Erdem, K. Kiraz, M. Somer, R.A. Eichel, Size effects in Fe3+-doped PbTiO3 nanocrystals-formation and orientation of (Fe'Ti-Vo^ •) defect-dipoles, Journal ofthe European Ceramic Society 30 (2010) 289-293.

[29] B. Li, G. Li, Q. Yin, Z. Zhu, A. Ding, W. Cao, Pining and depinning mechanism of defect dipoles in PMnN-PZT ceramics, Journal of Physics D: Applied Physics 38 (2005)1107-1111.

[30] N. Wongdamnern, N. Triamnak, A. Ngamjarurojana, Y. Laosiritaworn, S. Ananta, R. Yimnirun, Comparative studies of dynamic hysteresis responses in hard and soft PZT ceramics, Ceramics International 34 (2008) 731-734.

[31] H.W. Walter, L. Karl, W. Wolfram, Piezoeletricity: Evolution and Future of a Technology, 2008, Springer Series in Materials Science.