Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 17) pp:13076-13083
Publication Date(Web):19 May 2017
DOI:10.1007/s10854-017-7140-y
Here we fabricated the (1−y)[(1−x)BiFeO3–xBaTiO3]–yBi(Zn0.5Ti0.5)O3 ceramics by the conventional solid-state method, and then a large piezoelectric constant (d33) of ~195 pC/N together with a high Curie temperature (TC = 505 °C) could be attained in the ceramics by building the rhombohedral–cubic (R–C) phase boundary. The R–C phase coexistence can be shown in the ceramics with 0.25 ≤ x ≤ 0.35 and 0.01 ≤ y ≤ 0.05. In particular, both a high remnant polarization (Pr = 18.5 μC/m2) and a relatively high strain of ~0.19% were also observed in the phase coexistence region. In addition, the thermal stability together with the effects of polarization temperature and cooling-down method was also explored.
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 6) pp:4828-4838
Publication Date(Web):26 November 2016
DOI:10.1007/s10854-016-6129-2
We profoundly investigated the composition dependence of electrical properties in (1 − x)KNbO3–xNaNbO3 [(1 − x)KN–xNN] ceramics. A phase diagram can be established in (1 − x)KN–xNN according to their temperature dependence of dielectric constant. In addition, the optimization of processing and poling conditions can be attained in the ceramics with x = 0.525. The density of (1 − x)KN–xNN ceramics with x = 0.50 reached the highest value of 4.31 g/cm3 when sintered at 1110 °C. The (1 − x)KN–xNN ceramics with x = 0.525 exhibited optimum electrical properties of d33 ~ 106 pC/N, kp ~ 0.35, Pr ~ 10.5 μC/cm2, Ec ~ 11.1 kV/cm, and TC ~ 425 °C. We thought that the systematical and profound studies can clearly know about the intrinsic characteristics of (1 − x)KNbO3–xNaNbO3 lead-free ceramics.
In this work, the multiphase coexistence of rhombohedral-orthorhombic and orthorhombic-tetragonal (R-O/O-T) was constructed in (1-x-y)BaTiO3-xCaTiO3-yBaZrO3 ceramics with 0.14 ≤ x ≤ 0.16 and 0.10 ≤ y ≤ 0.12, and thus a large piezoelectric constant (d33) of 600 pC/N was attained in the ternary (1-x-y)BaTiO3-xCaTiO3-yBaZrO3 ceramics using the optimization of x and y. The R-O/O-T multiphase coexistence as well as the enhancement of dielectric and ferroelectric properties can be responsible for the high d33 of this work. In addition, a high strain of 0.15% was observed in the multiphase coexistence. As a result, electrical properties of BaTiO3 can be optimized by the construction of multiphase coexistence through the co-doping of CaTiO3 and BaZrO3.
Journal of Materials Chemistry A 2016 vol. 4(Issue 25) pp:6140-6151
Publication Date(Web):23 May 2016
DOI:10.1039/C6TC01629D
Multiferroic bismuth ferrite (BiFeO3, BFO) is one of the most promising high-temperature ferroelectric and piezoelectric materials due to a high Curie temperature (TC ∼ 825 °C) if the enhancement of ferroelectricity and piezoelectricity can be realized. Unfortunately, it is difficult to adequately pole BFO ceramics due to a high coercive field as well as a high leakage current. Here we investigated the defect dipole-induced poling characteristics and the ferroelectric properties of four kinds of A or/and B-doped BFO ceramics (i.e. BiFeO3, Bi0.95Sm0.05FeO3, BiFe0.95Sc0.05O3, and Bi0.95Sm0.05Fe0.95Sc0.05O3) using a modified quenching technique. The piezoelectric effect is determined by the poling condition, and moreover the poling behavior is strongly dependent on the ion substitution types of BFO ceramics. An enhanced piezoelectric property (d33 = 46–51 pC N−1) can be attained without the involvement of a phase boundary. Specifically, the doping with Sm (Bi0.95Sm0.05FeO3) can cause an obvious threshold during poling, and additionally Bi0.95Sm0.05FeO3 and Bi0.95Sm0.05Fe0.95Sc0.05O3 components can be curiously adequately poled below the coercive field at the poling temperature of 100 °C. In addition, the saturated P–E loops with an obvious internal bias field (Ei) were observed, where Ei was induced by defect dipoles , and then defect dipoles may be decoupled at 120 °C and 6 kV mm−1 (DC field), resulting in a cyclical poling current. It is of great interest to note that an enhanced remanent polarization (2Pr ∼ 50–60 μC cm−2) of the ceramics is obtained, and especially the internal bias fields can be alleviated by AC-cycling or decreasing the measurement frequency. Finally, we believe that our research will have a significant importance in the improvement of piezoelectricity of BFO-based ceramics.
The controversy about the optimum poling conditions of (K,Na)NbO3 (KNN)-based lead-free ceramics was still unresolved and the relationships between poling characteristics and phase boundary types were rarely mentioned. Here, we tried to unveil the relationships between poling characteristics and phase boundary types of these ceramics. The optimum poling temperatures should be chosen near their corresponding phase transition temperatures. In addition, a large piezoelectricity can be attained in the ceramics with a multiphase coexistence under a lower poling electric field (
A large piezoelectric constant (d33) of ∼480 pC/N was attained in new ternary (1–x–y)K0.5Na0.5Nb0.96Sb0.04O3-xBaSnO3-yBi0.5Na0.5ZrO3 ceramics by forming rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary using the variations of x and y, and such a phase boundary was successfully confirmed by the convergent beam electron diffraction (CBED) patterns. For (1–x)K0.5Na0.5Nb0.96Sb0.04O3-xBaSnO3, the orthorhombic (O) phase is well-maintained for 0 ≤ x ≤ 0.015, and both the R and T phases can be introduced to (0.99–y)K0.5Na0.5Nb0.96Sb0.04O3-0.01BaSnO3-yBi0.5Na0.5ZrO3 with y = 0.025–0.04 by simultaneously tailoring their compositions (x and y); then, R-O-T multiphases can be well-established. The CBED patterns strongly support the existence of R-O-T multiphases in the ceramics with y = 0.035. When the phase transitions endure from O to R-O-T, their piezoelectric activity endures a leapfrog development from ∼165 to ∼480 pC/N. In the region of the R-O-T phase boundary, a large d33 of ∼480 pC/N was attained in the ceramics with x = 0.01 and y = 0.035. In addition, the ceramics with x = 0.01 and y = 0.04 possess a high strain of ∼0.274% due to the multiphases coexistence. According to the variations of dielectric and ferroelectric properties, the enhancement in εr and Pr plays a part in the improved d33 except for the R-O-T phase boundary. We believe that the (K, Na)NbO3 ternary systems can be used to promote piezoelectric activity by forming new phase boundaries.
Colossal permittivity (CP) materials continue to attract significant interest for their applications in high-performance capacitors and scaling advances in electronic devices. However, the unbalanced developments of their dielectric constants, dielectric losses, and stabilities still hinder practical applications. In this study, we attained a colossal permittivity (εr = 104∼105, 1 kHz) in a series of new titanium dioxide (i.e., (A0.5Ta0.5)xTi1−xO2, where A = Al, Sm, Bi, Fe, In, Dy, Ga, Gd, Yb, or Sc) ceramics containing Ta and trivalent elements that is comparable or superior to the previously reported results in In and Nb co-doped ceramics. In addition, a low dielectric loss (tan δ∼5.4%, 1 kHz) was achieved in the ceramics by tailoring the types of trivalent elements used; such a ceramic also shows relatively good dielectric properties with regard to frequency (102∼106 Hz) and temperature (−150–200 °C) stabilities. The formation of defect-dipole clusters (e.g., and Ta5+Ti3+ATi (A = Ti3+/Al3+/Ti4+)) induced by Ta and trivalent elements should be responsible for the observed enhancements in dielectric properties. We believe that TiO2-based ceramics are one of the most promising candidates in the field of electronic and energy-storage devices.
In this study, we systematically investigated the composition dependence of the phase structure, microstructure, and electrical properties of (Ba0.94Ca0.06)(Ti1–xMx)O3 (M = Sn, Hf, Zr) ceramics synthesised by the conventional solid-state reaction method. The phase boundary type strongly depends on the composition, and then different electrical properties were exhibited. The addition of Hf and Zr can more quickly shift phase transition temperatures (TR–O and TO–T) to a higher temperature with respect to Sn, leading to the formation of different phase boundaries. In addition, different phase boundaries can also be affected by their doped contents. The R–O and O–T phase boundaries can be shown in the Sn-doped ceramics with x = 0.10, and the R–O phase boundary can exist in the Hf (x = 0.07) or Zr (x = 0.075)-doped ceramics. A high piezoelectric property of d33 = 600 pC N−1 can be achieved in the Sn-doped ceramics due to the involvement of converging R–O/O–T phase boundaries, an enhanced ferroelectric performance with Pr = 14.54 μC cm−2 and Ec = 1.82 kV cm−1 can be attained in the Zr-doped ceramics, and Hf would benefit from obtaining a large strain behaviour (∼0.20%). We believe that the electrical properties and the related physical mechanisms of BaTiO3-based ceramics can be well unveiled by studying their chemical modification behavior.
Journal of Alloys and Compounds 2016 Volume 676() pp:505-512
Publication Date(Web):15 August 2016
DOI:10.1016/j.jallcom.2016.03.205
•Developing the quenched technique for fabricating Bi1.05FeO3BaTiO3 ceramics.•Attaining high TC (457 °C), large d33 (170 pC/N), and high Pr (22 μC/cm2).•Illuminating the physical mechanism for enhanced electrical properties.In this work, the quenched method can effectively promote the electrical properties of bismuth ferrite-barium titanate (BiFeO3BaTiO3, BFO-BTO) ceramics. Here we mainly focused on the modification of the quenched methods in the 0.67Bi1.05FeO3–0.33BaTiO3 ceramics with rhombohedral-cubic phase boundary. By optimizing the preparation conditions, the ceramics possess high Curie temperature (TC∼457 °C), large piezoelectricity (d33∼170 pC/N), and good ferroelectricity (Pr∼22 μC/cm2). The enhanced electrical properties are mainly assigned to the quenching technique with optimized conditions. We believe that such a systematic research can point out a way for further fabricating high-performance ceramics.
Journal of Alloys and Compounds 2016 Volume 666() pp:372-379
Publication Date(Web):5 May 2016
DOI:10.1016/j.jallcom.2016.01.105
•Establishing orthorhombic and tetragonal phases boundary.•Attaining high piezoelectric activity (d33 = 550 pC/N).•Illuminating physical origin for the enhanced electrical properties.The (1−x)(Ba0.93Ca0.07)TiO3-xBa(Sn1−yHfy)O3 (BCTSH-x-y) lead-free ceramics were synthesised by the conventional solid-state reaction method, and the influences of doping elements (Ca, Sn, Hf) content on their phase structure, microstructure, and electrical properties were systematically investigated. The phase boundaries concerning the orthorhombic and tetragonal (O-T) phases were found in the 0.925(Ba0.93Ca0.07)TiO3-0.075Ba(Sn1-yHfy)O3 ceramics with 0 ≤ y ≤ 0.25, and then the enhanced piezoelectric properties with d33 ∼ 550 pC N−1 were obtained. In addition, the addition of Hf can also improve the Curie temperature (TC) and ferroelectric properties of the ceramics. As a result, the electrical properties of BaTiO3 can be optimized by the construction of phase boundaries through Ca, Sn, and Hf co-doping.
Journal of Alloys and Compounds 2016 Volume 684() pp:217-223
Publication Date(Web):5 November 2016
DOI:10.1016/j.jallcom.2016.04.322
•Constructing orthorhombic-tetragonal phase coexistence for 0.03 < x < 0.055.•Identifying phase boundary using temperature-dependent Raman spectra.•Attaining large d33 of ∼385 pC/N as well as high TC of ∼315 °C.In this work, the (1-x)K0.45Na0.55NbO3-xBi0.5Na0.5HfO3 lead-free ceramics with a high Curie temperature were prepared by the normal sintering, and the enhancement in strain and piezoelectricity can be attained by tailoring the corresponding compositions. The orthorhombic-tetragonal (OT) phase coexistence was observed in the ceramics with 0.03 < x < 0.055, and then such a phase boundary was reasonably identified by X-ray diffraction patterns as well as temperature -dependent Raman spectra and dielectric constant. A large piezoelectric constant (d33) of ∼385 pC/N and a high Curie temperature (TC) of ∼315 °C can be simultaneously induced in the ceramics with x = 0.05. More interestingly, a high unipolar strain of ∼0.187% was shown in the ceramics with x = 0.04. It was found that the enhanced piezoelectric properties should be attributed to the two phase coexistence as well as enhanced dielectric and ferroelectric properties. We believe that this material is one of the most promising candidates in the field of high-temperature piezoelectrics.
Science China Technological Sciences 2016 Volume 59( Issue 7) pp:1029-1035
Publication Date(Web):2016 July
DOI:10.1007/s11431-016-6051-0
In this work, we have studied a new lead-free ceramic of (1−y)Bi1−xNdxFeO3-yBiScO3 (0.05≤x≤0.15 and 0.05≤y≤0.15) prepared by a conventional solid-state method, and the influences of Nd and Sc content on their phase structure and electrical properties were investigated in detail. The ceramics with 0.05≤x≤0.10 and 0.05≤y≤0.15 belong to an R3c phase, and the rhombohedral-like and orthorhombic multiphase coexistence is established in the composition range of 0.125≤x≤0.15 and y=0. The electrical properties of the ceramics can be enhanced by modifying x and y values. The highest piezoelectric coefficient (d33~51 pC/N) is obtained in the ceramics with x=0.075 and y=0.125, which is superior to that of a pure BiFeO3 ceramic. In addition, a lowest dielectric loss (tan δ~0.095%, f=100 kHz) is shown in the ceramics with x=0.15 and y=0 due to the involvement of low defect concentrations, and the improved thermal stability of piezoelectricity at 20–600°C is possessed in the ceramics. We believe that the ceramics can play a meaningful role in the high-temperature lead-free piezoelectric applications.
Journal of Materials Chemistry A 2015 vol. 3(Issue 31) pp:15951-15961
Publication Date(Web):16 Jun 2015
DOI:10.1039/C5TA03511B
In this work, we confirmed the electric-induced transition (EPT) in (K,Na)NbO3-based ceramics through experiment and theory. Through in situ X-ray diffraction measurements, electric field-induced phases (EPs) could be observed in the ceramics. To explain the appearance of EPs, a new function λ(Eex) was introduced into the six order Devonshire theory when the external electric field was applied. Further studies indicate that EPT had two possible forms, i.e., tetragonal-electric induced phase transition (T-EP) and rhombohedral-electric induced phase transition (R-EP), and T-EP plays a more positive role than R-EP in terms of the piezoelectric response. Also, a giant piezoelectricity (d33 = 435–490 pC N−1), a high Curie temperature (TC = 205–234 °C), and a converse piezoelectric coefficient (d*33 = 500–890 pm V−1) can be achieved by choosing optimum metal oxides as well as their content. We believe that such work could help to further study the physical mechanisms of giant piezoelectricity in potassium–sodium niobate.
Journal of Materials Chemistry A 2015 vol. 3(Issue 13) pp:6772-6780
Publication Date(Web):24 Feb 2015
DOI:10.1039/C5TA00732A
Here, we report enhanced piezoelectricity over a very wide sintering temperature range (400–1050 °C) in 0.96(K0.4Na0.6)(Nb0.96Sb0.04)O3–0.04Bi0.5K0.5Zr0.9Sn0.1O3 lead-free ceramics prepared by two step sintering. All ceramics fall into the R–T phase boundary at room temperature, and a dense microstructure without serious loss of alkali elements was found in the samples. The enhanced dielectric, ferroelectric, and piezoelectric properties were attained by two step sintering over a wide sintering temperature range of 400–1050 °C. Most interestingly, the enhanced d33 values of 350–400 pC N−1 can be achieved over a wide temperature range of 400–1050 °C, and the temperature gap range of 650 °C is much wider with respect to previous studies by two step sintering. Besides, an enhanced unipolar strain of ∼0.26% (d*33 ∼ 736 pm V−1) can also be attained in the ceramics.
Co-reporter:Xiaojing Cheng, Zhenwei Li and Jiagang Wu
Journal of Materials Chemistry A 2015 vol. 3(Issue 11) pp:5805-5810
Publication Date(Web):28 Jan 2015
DOI:10.1039/C5TA00141B
The appearance of colossal permittivity (CP) materials broadens the choice of materials for energy-storage applications. Here we report colossal permittivity in ceramics of TiO2 co-doped with niobium and trivalent cation {i.e., (A0.5Nb0.5)xTi1−xO2, A = Bi, Pr, Dy, Sm, Gd, Yb, Ga, Al or Sc}, in particular in the (Bi0.5Nb0.5)xTi1−xO2 ceramic system that was selected as a candidate material. A very large dielectric constant (εr ∼ 4.2 × 104) and a low dielectric loss (tanδ ∼ 8.3%) were observed for (Bi0.5Nb0.5)xTi1−xO2 ceramics when measured at 1 kHz. Moreover, the addition of Bi and Nb can enhance the temperature stability (between −125–200 °C) and frequency stability (between 102 to 106 Hz) of εr and tanδ. The electron-pinned defect-dipoles are considered to be responsible for both their high εr and low tanδ, which is consistent with changes of valence states determined by X-ray photoelectron spectroscopy. We believe that the TiO2 ceramics as a CP material constitute one of the most promising candidates for high-energy-density storage applications.
Co-reporter:Ting Zheng, Jiagang Wu, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang and Xiaojie Lou
Journal of Materials Chemistry A 2015 vol. 3(Issue 5) pp:1868-1874
Publication Date(Web):19 Dec 2014
DOI:10.1039/C4TA05423G
The obvious conflicts between large piezoelectricity and high strain could be solved by developing new phase boundaries in potassium–sodium niobate materials. Here, we have solved this problem by extensive experimental researches and induced a larger strain as well as a higher piezoelectricity in (K, Na)NbO3. Large converse piezoelectric coefficient (d*33 = 599–1553 pm V−1) and high strain (0.18–0.46%) were achieved, which are the highest values reported to date in potassium–sodium niobate, suggesting that such a system is a promising lead-free candidate for electromechanical actuator applications. In addition, high d33 values of 400–490 pC N−1 have also been attained in the ceramic due to its rhombohedral–tetragonal phase boundary, as well as its composition.
Journal of Materials Chemistry A 2015 vol. 3(Issue 43) pp:11326-11334
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5TC02203G
Poor piezoelectric activity is often observed in BiFeO3 ceramics due to their low resistivity and high coercive field, which can easily result in piezoelectric breakdown before the domains are switched. Here, we attained a high piezoelectricity using a series of bismuth ferrite ceramics substituted by rare earth elements and transition metal elements {e.g., Bi0.925La0.05A0.025FeO3, A: Sm, Yb, Ho, Y, Nd, Pr, Dy, Gd; Bi0.925La0.05Sm0.025Fe0.95M0.05O3, M: Sc, In, Al, Ga, Ni, Co} fabricated using the conventional solid-state method. The influences of site engineering (e.g., Bi site or Fe site) as well as the doped element types on their phase structure, microstructure, and electrical properties have been comparatively analyzed. The ions (e.g., A = Sm, Yb, Ho, and Y) substituting at the Bi site are helpful to attain both a pure phase structure and a relatively good piezoelectricity (d33 ≥ 40 pC N−1) for BFO ceramics, while ion substitutions at the Fe site cannot suppress the formation of impurity phases which results in degraded electrical properties. Both XRD and backscattered electron images fully confirmed the existence of impurity phases (Bi-rich and Fe-rich counterparts) in the ceramics doped by Ga. According to the related experiments, the piezoelectric properties of bismuth ferrite ceramics can be promoted by site engineering as well as the optimization of the element types. This result will point out a way for us to promote the piezoelectric properties of bismuth ferrite ceramics through choosing both suitable doping elements and eliminating impurity phases.
Journal of Materials Chemistry A 2015 vol. 3(Issue 35) pp:9206-9216
Publication Date(Web):03 Aug 2015
DOI:10.1039/C5TC01659B
In this study, colossal permittivity (CP) (104–105) is attained in the (Sm0.5Ta0.5)xTi1−xO2 ceramics, and their dielectric loss can be further decreased by doping oxides and optimizing the sintering temperatures. The effects of Sm and Ta as well as the oxides on their microstructure, dielectric properties, and stability were studied in detail. The secondary phases were induced by doping excessive Sm and Ta, and then both backscattering and EDS confirmed that excessive Sm and Ta result in the generation of secondary phases. The relationships between secondary phases and dielectric properties were established. The formation of secondary phases decreases their dielectric constant, whereas their dielectric loss can be slightly decreased through the optimization of Sm and Ta content. In addition, all the ceramics possess an improved frequency (102–106 Hz) and temperature (−150–200 °C) stability of dielectric properties. Moreover, the addition of oxides containing trivalent (Bi3+) or pentavalent (Sb5+ and Nb5+) elements can further reduce their dielectric loss. Through the results of XPS, the formation of defect-dipole clusters, e.g., and Ta5+Ti3+ATi (A = Ti3+/Sm3+/Ti4+), induced by Sm and Ta should be mainly responsible for enhanced dielectric properties.
Co-reporter:Jin-Song Zhou, Ke Wang, Fang-Zhou Yao, Ting Zheng, Jiagang Wu, Dingquan Xiao, Jianguo Zhu and Jing-Feng Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 34) pp:8780-8787
Publication Date(Web):14 Jul 2015
DOI:10.1039/C5TC01357G
Growing environmental concerns are pushing the development of lead-free piezoceramics with both outstanding piezoelectric properties and reasonable thermal stability. Herein, we realized a large piezoelectric coefficient d33 of 430 pC N−1 in 0.96(K0.4Na0.6)(Nb0.96Sb0.04)O3–0.04Bi0.5K0.5Zr0.85Sn0.15O3 (KNNS–BKZS) polycrystals by constructing a rhombohedral–tetragonal (R–T) phase boundary. Investigations of the in situ thermal stability of the piezoelectric properties on multiple scales reveal that the micro-scale piezoelectric response is much more stable compared to the macro-scale response, indicating the significant role of extrinsic contributions from domain wall movements. These findings demonstrate the relationship between multi-scale properties and domain structures, revealing that the high piezoelectricity is attributed to nano-domains at the R–T phase boundary.
Journal of Materials Chemistry A 2015 vol. 3(Issue 15) pp:3684-3693
Publication Date(Web):18 Feb 2015
DOI:10.1039/C5TC00363F
We have developed a high-temperature bismuth ferrite ceramics with enhanced piezoelectric activity by chemical modifications, that is, the Bi1−x−ySmxLayFeO3 (0 ≤ x ≤ 0.30 and 0 ≤ y ≤ 0.15) lead-free ceramics were prepared by a conventional solid-state method. The influences of La and Sm content on their microstructure and electrical properties were systematically investigated. The ceramics with 0 ≤ x < 0.10 (y = 0.05) or 0 ≤ y ≤ 0.15 (x = 0.025) belong to a triclinic phase, and a mixed structure with rhombohedral-like and orthorhombic phases was found in the ones with 0.10 ≤ x ≤ 0.30 (y = 0.05). The electrical properties of the ceramics can be operated by refining the x and y values. A very low dielectric loss (tanδ ∼ 0.43%) was shown in the ceramics with x = 0.025 and y = 0.05 because of the involvement of low defect concentrations. In addition, the ceramics with x = 0.025 and y = 0.05 also possess a high piezoelectric activity (d33 ∼ 50 pC N−1), which is larger with the respect to the previously reported results in high-temperature piezoceramics with a Curie temperature of >600 °C, and a better thermal stability of piezoelectricity in 20–700 °C is also shown. We believe that this material system is suitable for high-temperature piezoelectric applications.
In this work, (1 − x)(K0.48Na0.52)(Nb0.95−y−zTazSby)O3-xBi0.5(Na0.82K0.18)0.5ZrO3, {abbreviation: KNNST-BNKZ-x-y-z} lead-free piezoceramics were prepared by a conventional solid-state reaction method, and the composition dependence of their phase structures and electrical properties was systematically discussed. Doping with Sb5+, Ta5+, and BNKZ plays an important role on the phase boundaries as well as piezoelectric activity. A three-phase coexistence involving rhombohedral-orthorhombic-tetragonal (R–O–T) phases was observed in the ceramics with 0.0325 ≤ x ≤ 0.05, 0.035 ≤ x ≤ 0.065, 0.05 ≤ z ≤ 0.08, indicating that doping with BNKZ, Ta5+, and Sb5+ can induce the formation of such a phase boundary by simultaneously increasing TR–O and decreasing TO–T. Enhanced piezoelectric behavior was observed in the ceramics located in the composition region of the R–O–T phase boundary, and a high d33 value of 400 pC N−1 can be attained by refining their compositions (e.g., x = 0.0325, y = 0.035, and z = 0.05), together with a high TC value of ∼240 °C. Of particular interest is that a large electric field-induced strain of 0.18% (Smax/Emax = 706 pm V−1) was also found in the ceramics with x = 0.0325, y = 0.035, and z = 0.05 under a low electric field of 2.5 kV mm−1. As a result, the piezoelectric activity as well as the strain can be operated in the material system by refining x, y, and z content.
In this work, we simultaneously achieved a giant d33 and a high TC in a lead-free piezoelectric ternary system of (1 − x − y)K0.48Na0.52NbO3–xBiFeO3–yBi0.5Na0.5ZrO3 {(1 − x − y)KNN–xBF–yBNZ}. Owing to the rhombohedral–orthorhombic–tetragonal (R–O–T) phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramics with a composition of (x = 0.006, y = 0.04) show a giant d33 of ∼428 pC N−1 together with a TC of ∼318 °C, thereby proving that the design of ternary systems is an effective way to achieve both high d33 and high TC in KNN-based materials. In addition, a good thermal stability for piezoelectricity was also observed in these ceramics (e.g., d33 > 390 pC N−1, T ≤ 300 °C). This is the first time such a good comprehensive performance in potassium–sodium niobate materials has been obtained. As a result, we believe that this type of material system with both giant d33 and high TC is a promising candidate for high-temperature piezoelectric devices.
Co-reporter:Xiang Lv, Jiagang Wu, Dingquan Xiao, Yuan Yuan, Hong Tao, Jianguo Zhu, Xiangjian Wang and Xiaojie Lou
RSC Advances 2015 vol. 5(Issue 49) pp:39295-39302
Publication Date(Web):14 Apr 2015
DOI:10.1039/C5RA02260F
In this work, a high unipolar strain has been developed in the 0.9675(K0.48Na0.52)(Nb0.915Sb0.035Ta0.05)O3–0.0325(Bi1−xSmx)0.5(Na0.82K0.18)0.5ZrO3 (KNNST-B1−xSxNKZ) ceramics by introducing Sm, and the composition dependence of their phase structures and electrical properties is also discussed. The addition of Sm3+ can change the phase structure of the ceramics by simultaneously shifting TR–O and TO–T to a higher temperature, and we obtained a rhombohedral–orthorhombic–tetragonal coexistence phase (R–O–T) with x = 0, a coexistence phase having orthorhombic and tetragonal (O–T) phases with 0.05 ≤ x ≤ 0.60 and an orthorhombic phase with 0.8 ≤ x ≤ 1.0. In addition, the doping with Sm3+ can greatly enhance the unipolar strain of the ceramics without significantly sacrificing its TC, and a high unipolar strain (∼0.28%) was observed in the ceramics with x = 0.20. More importantly, a large Smax/Emax of ∼833 pm V−1 was also observed in the ceramics with x = 0.20 under a low applied electric field of 1.8 kV cm−1. We believe that such a high unipolar strain can benefit the practical applications of actuators.
Co-reporter:Jiagang Wu, Hong Tao, Yuan Yuan, Xiang Lv, Xiangjian Wang and Xiaojie Lou
RSC Advances 2015 vol. 5(Issue 19) pp:14575-14583
Publication Date(Web):02 Feb 2015
DOI:10.1039/C4RA14271C
In the past ten years, antimony has been reported to strongly affect the developments in the piezoelectric properties of (K,Na)NbO3 (KNN) lead-free ceramics, that is, its enhanced piezoelectric activity is closely related to the doped antimony as well its content. In this work, we clarified the role of Sb5+ in the construction of a phase structure and the enhancement of electrical properties of a pure KNN ceramic. Research has shown that doping with Sb5+ can simultaneously move their orthorhombic–tetragonal phase transition temperature (TO–T) and rhombohedral–orthorhombic phase transition temperature (TR–O) forward to room temperature, benefiting the formation of three types of phase boundaries. The coexistence of rhombohedral and orthorhombic phases was established in the Sb5+ composition range of 0.07–0.09 by this regulation. In addition, their grain sizes were determined by the Sb5+ content, that is, the optimum Sb5+ content (x ≤ 0.05) induces grain growth, and their grain sizes become considerably smaller when the compositions deviate from x > 0.05. More importantly, their electrical properties could be also tuned by changing the Sb5+ content. Their dielectric, ferroelectric, and piezoelectric properties are strongly dependent on the antimony content, whereas the strain behavior is mainly ascribed to the multi-phase transition region as well as the structural change of phase transitions. As a result, this work would help to further understand the underlying physical origin for enhanced electrical properties in alkali niobate ceramics.
Journal of Alloys and Compounds 2015 Volume 651() pp:302-307
Publication Date(Web):5 December 2015
DOI:10.1016/j.jallcom.2015.08.051
•Effects of barium content on phase structure and electrical properties of KNNS–BxBNZ ceramics were investigated.•A R–T phase boundary appears in the ceramics with x = 0–0.20.•The ceramic with x = 0.15 has the largest d33 ∼ 360 pC/N, together with a good temperature stability of ferroelectricity.In this work, effects of barium content on phase structure, microstructure, and electrical properties of 0.96K0.45Na0.55Nb0.96Sb0.04O3–0.04Bax(Bi0.5Na0.5)1−xZrO3 ceramics have been investigated. Their grain sizes climb up and then decline with increasing Ba2+ content, and Ba2+ is homogenously distributed in the matrix. With adding Ba2+ to replace both Bi3+ and Na+, it slightly influences the TC. A rhombohedral–tetragonal (R–T) phase boundary appears in the ceramics with the compositional range of x = 0–0.20, drastically enhancing both dielectric and piezoelectric properties of the ceramics. In addition, the ceramic with x = 0.15 has the largest d33 ∼ 360 pC/N, together with a good temperature stability of ferroelectricity and an enhanced thermal stability of piezoelectricity. Therefore, it is proved that such a ceramic system is a promising candidate for piezoelectric devices.
Journal of the American Chemical Society 2014 Volume 136(Issue 7) pp:2905-2910
Publication Date(Web):February 5, 2014
DOI:10.1021/ja500076h
Environment protection and human health concern is the driving force to eliminate the lead from commercial piezoelectric materials. In 2004, Saito et al. [Saito et al., Nature, 2004, 432, 84.] developed an alkali niobate-based perovskite solid solution with a peak piezoelectric constant d33 of 416 pC/N when prepared in the textured polycrystalline form, intriguing the enthusiasm of developing high-performance lead-free piezoceramics. Although much attention has been paid on the alkali niobate-based system in the past ten years, no significant breakthrough in its d33 has yet been attained. Here, we report an alkali niobate-based lead-free piezoceramic with the largest d33 of ∼490 pC/N ever reported so far using conventional solid-state method. In addition, this material system also exhibits excellent integrated performance with d33∼390–490 pC/N and TC∼217–304 °C by optimizing the compositions. This giant d33 of the alkali niobate-based lead-free piezoceramics is ascribed to not only the construction of a new rhombohedral–tetragonal phase boundary but also enhanced dielectric and ferroelectric properties. Our finding may pave the way for “lead-free at last”.
Co-reporter:Ting Zheng, Jiagang Wu, Xiaojing Cheng, Xiaopeng Wang, Binyu Zhang, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang and Xiaojie Lou
Journal of Materials Chemistry A 2014 vol. 2(Issue 41) pp:8796-8803
Publication Date(Web):22 Sep 2014
DOI:10.1039/C4TC01533A
We have attained both large piezoelectricity and high strain in (1 − x)(K0.40Na0.60)(Nb0.955Sb0.045)O3–xBi0.50Na0.50ZrO3 [(1 − x)KNNS–xBNZ] lead-free ceramics by forming a rhombohedral (R) and tetragonal (T) phase boundary. The ceramics with 0.035 < x < 0.05 possess R and T phases' coexistence. A large d33 value of ∼450 pC N−1 has been attained when the x value reached 0.04 owing to the involved R–T phase boundary, which is higher with respect to d33 ∼ 416 pC N−1 of textured (K,Na,Li)(Nb,Ta,Sb)O3 ceramics reported by Saito et al. [Nature, 2004, 432, 84]. In addition, it is worth noting that such a ceramic simultaneously possesses a high electric field-induced strain (0.2%) under a low driving electric field of ∼2 kV mm−1, and its Smax/Emax value is equal to be 1071 pm V−1. As a result, we can believe that the (1 − x)KNNS–xBNZ ceramics will become one of the promising material systems in the practical applications of electrical devices.
Journal of Materials Chemistry A 2014 vol. 2(Issue 12) pp:4122-4126
Publication Date(Web):12 Feb 2014
DOI:10.1039/C3TA15075E
To protect the environment and human health, it is necessary to develop high-performance lead-free piezoceramics to replace the lead-based ones in some electronic devices. Here we report first a large piezoelectricity in (K,Na)NbO3-based lead-free piezoceramics prepared by the conventional solid-state method. The rhombohedral–tetragonal phase boundary is observed in the ceramics with a composition of 0.04 ≤ x ≤ 0.06. Those ceramics with 0.01 ≤ x ≤ 0.06 possess a good comprehensive performance of d33 (380–460 pC N−1) and TC (170–287 °C). Moreover importantly, a peak d33 of ∼460 pC N−1 is shown in the ceramic with x = 0.04, which is superior to all other reported results of KNN-based ceramics, including the reported results by Saito et al. (Nature, 2004, 432, 84). We believe that such a material system is a very promising candidate for potassium–sodium niobate piezoceramics.
For potassium–sodium niobate, poor piezoelectric properties always perplex most researchers, and then it becomes important to attain a giant piezoelectricity. Here we reported a giant piezoelectric constant in (1 – x)(K0.48Na0.52)(Nb0.95Sb0.05)O3-xBi0.5Ag0.5ZrO3 lead-free ceramics. The rhombohedral-tetragonal phase boundary was shown in the ceramics with 0.04 < x ≤ 0.05, and then the ceramic with x = 0.0425 possesses a giant d33 of ∼490 pC/N. We also discussed the physical mechanisms of enhanced piezoelectricity. As a result, such a research can benefit the sustainable development of (K,Na)NbO3 materials.Keywords: high piezoeletricicty; lead-free ceramics; potassium−sodium niobate;
A high strain is important for practical applications of piezoelectric actuators. Here we reported a high strain in the (K,Na)NbO3 -based ceramics by doping alkaline earths or transition metals. The ceramics possess a high strain (∼0.29%) as well as a large converse piezoelectric coefficient (d33*) up to 688 pm/V, which almost matches that of PZT4 ceramics. The obtained d33* is high for nontextured (K,Na)NbO3-based ceramics. In addition, a higher d33 value (340–407 pC/N) was also attained in the ceramics. Enhanced d33 and d33* values of this work should be attributed to the multiphase coexistence’s effect induced by alkaline earths or transition metals. We believe that our research can benefit the developments of (K,Na)NbO3 ceramics and widen their applications range.Keywords: (K,Na)NbO3; high strain; lead-free piezoceramics
Both giant d33 and high TC have been obtained in a lead-free piezoelectric ternary system (0.995 – x)K0.48Na0.52NbO3-0.005BiScO3-xBi0.5(Na0.7K0.2Li0.1)0.5ZrO3. Thanks to the rhombohedral-tetragonal phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramic with a composition of x = 0.04 shows a giant d33 of ∼366 pC/N together with TC of ∼335 °C, thereby paving the way for achieving both high d33 and high TC in KNN-based materials. In addition, such a ceramic has a good thermal stability of d33 (e.g., d33 > 319 pC/N, T ≤ 300 °C) and an enhanced stability of ferroelectric properties against temperature. The domain-wall energy barrier of ∼0.15 eV is derived from the temperature dependence of the back-switching polarization.Keywords: high Curie temperature; lead-free piezoelectrics; piezoelectricity; R-T phase boundary; ternary system;
(1 − x)(K0.48Na0.52)(Nb0.95Ta0.05)O3–xBi0.5(Na0.7K0.2Li0.1)0.5ZrO3 lead-free piezoelectric ceramics with a new type of phase boundary have been designed and fabricated. This phase boundary lies in the compositional range of 0.04 ≤ x ≤ 0.05, and is formed by the coexistence of the rhombohedral, orthorhombic, and tetragonal phases. Interestingly, we found that the ferroelectric, dielectric, and piezoelectric properties of the ceramics with compositions near the phase boundary are significantly enhanced. In particular, the ceramic with x = 0.045 shows the best piezoelectric behavior of d33 ∼ 290 pC/N and kp ∼ 0.42 among all the compositions studied in this work, and it also exhibits a good thermal stability at annealing temperatures of ≤270 °C. All these results indicate that such a material system is a good candidate for lead-free piezoelectric applications in the future.
In this work, we elucidate the influence of Bi0.5Li0.5ZrO3 (BLZ) content on the phase structure, microstructure, and electrical properties of (1 − x)K0.40Na0.60Nb0.965Sb0.035O3–xBi0.5Li0.5ZrO3 lead-free ceramics. We simultaneously achieved a giant d33 and a high TC in this material system. The coexistence of rhombohedral and tetragonal phases is responsible for such a large d33 in the ceramics with BLZ contents (x) ranging from 0.025 to 0.035. Doping with BLZ not only induces the formation of the phase boundary, but also maintains a high TC. The ceramic with x = 0.03 shows an enhanced piezoelectric behaviour (d33 ∼ 400 pC N−1 and kp ∼ 0.47) together with a high TC of 292 °C. A good temperature stability for ferroelectricity and piezoelectricity is also observed in these ceramics. This study is the first time that such a good comprehensive performance has been obtained in potassium–sodium niobate materials. We believe that this type of material system possessing giant-d33 and high-TC is a promising candidate for use in high-temperature piezoelectric devices.
In this work, the two-step sintering technique is used to realize a high piezoelectric constant (d33) and wide sintering temperature range (TS) in the 0.955(K0.42Na0.58)(Nb0.96Sb0.04)O3–0.045(Bi0.5K0.5)0.90Zn0.10ZrO3 lead-free ceramics. Dense microstructures were developed in the ceramics by two-step sintering. In the TS range of 800–1130 °C, the rhombohedral–tetragonal phase boundary was well maintained, and these ceramics possess enhanced dielectric, ferroelectric, and piezoelectric properties. It is of great interest to note that a d33 of 323–416 pC/N could be attained in a temperature gap range of 330 °C. We believe that the two-step sintering could both widen the sintering temperature and obtain a high d33 for this material system.
In this work, the rhombohedral (R) and tetragonal (T) phase boundary of the 0.97(K0.4Na0.6)(Nb1−xSbx)O3–0.03Bi0.5Li0.5ZrO3 piezoceramics has been attained in a wide composition range of 0.035 ≤ x ≤ 0.08, and the Sb5+ could simultaneously shrink its TR–O and TO–T. A giant d33 of 380–405 pC N−1 and a TC of 200–292 °C have been observed in the ceramics with the coexistence of both R and T phases. In addition, the ceramics with 0.035 ≤ x ≤ 0.08 also show a good thermal stability of the d33, and an enhanced temperature stability of ferroelectricity could be observed in the ceramic with x = 0.035. As a result, adding the optimum antimony content is an efficient way to promote the electrical properties of potassium–sodium niobate ceramics with the R–T phase boundary.
Effects of both phase boundaries and poling conditions on the piezoelectric activity of (K,Na)NbO3 (KNN)-based ceramics {e.g., (1 − x) (K0.42Na0.58) (Nb0.96Sb0.04)O3–x(Bi0.5K0.5)0.90Zn0.10ZrO3 [(1 − x)KNNS–xBKZZ]} were studied in detail, and their d33 was promoted by refining the phase compositions and choosing optimum poling conditions (i.e., poling temperature, poling electric field, and second-poling process). The rhombohedral-tetragonal phase boundary was formed in the ceramics with 0.04 < x ≤ 0.05. In addition, their piezoelectric activity was further promoted by optimizing the poling temperatures and poling electric fields as well as the second-poling methods. The ceramics with x = 0.045 have enhanced piezoelectric activity (e.g., d33 ∼ 425 pC N−1 and kp ∼ 47%), and both d33 (425 pC N−1) and TC (248 °C) of this work can match well that (d33 ∼ 416 pC N−1 and TC ∼ 253 °C) of textured (Na,K,Li)(Nb,Ta,Sb)O3 ceramics. It is worth noting that a large strain (0.297%, Smax/Emax = 582 pm V−1) was also found in the ceramics with x = 0.04, which is superior to currently reported results in KNN-based ceramics.
Here we have realized three goals in a new potassium–sodium niobate material using CuO as sintering aid, such as low temperature sintering, the suppression in the loss of alkali metals, and attaining a high d33. Low-temperature sintered 0.96(K0.46Na0.54)Nb0.95Sb0.05O3–0.04Bi0.5(Na0.82K0.18)0.5ZrO3 ceramics were made conducting by adding CuO using an ordinary ceramic fabrication technique. The sintering temperatures drop from 1095 °C to 950 °C when the CuO content is increased from 0 to 2.5 wt%, and the K and Na loss could be also prevented under a low processing temperature. In addition, the ceramics undergo a phase transition with increasing CuO content, such as from a rhombohedral–tetragonal phase coexistence to the mixture of both rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries. The inhomogeneous Cu2+ distributions become more obvious as the CuO content rises, i.e., the excess Cu2+ aggregates at the small grains region for a low CuO content (x ≤ 1.5), and at the small and large grains zones for x = 2.5. The dielectric constant gradually decreases as the CuO increases, and the dielectric loss is lowered by adding CuO content. A well polarization vs. electric field (P–E) loop is seen in the ceramics with x ≤ 2.5, and those with x = 2.5 possess a high d33 of 310 pC N−1 even if the sintering temperatures drop down to 950 °C. As a result, it is an efficient way to promote the piezoelectricity of copper oxide-modified alkaline niobate ceramics using a low-temperature sintering technique.
(1−x)K0.42Na0.58Nb0.95Sb0.05O3–x[Bi0.5(Na0.82K0.18)0.5]0.95Pb0.05ZrO3 ceramics with rhombohedral–tetragonal phase boundary were designed to attain a giant piezoelectricity. Adding a low Pb content results in the dense microstructure, and the Pb element has been homogeneously distributed. The R–T phase boundary was formed in the ceramics with 0.035 < x ⩽ 0.045. In addition, an improved d33 of the ceramics with x = 0.04 was observed after second poling. Enhanced dielectric and piezoelectric properties of εr ∼ 2900, tan δ ∼ 0.022, d33 ∼ 460 pC/N, and kp ∼ 0.46 were observed in the ceramic with x = 0.04.
Ceramics International 2014 Volume 40(Issue 4) pp:5771-5779
Publication Date(Web):May 2014
DOI:10.1016/j.ceramint.2013.11.016
Abstract
A new phase boundary with rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries is designed in (K0.48Na0.52)NbO3 by adding Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3 (BNKLZ), where Zr4+ and (BNKL)2+ are respectively used to improve the temperature of a rhombohedral phase and to decrease the temperature of an orthorhombic–tetragonal phase coexistence. These ceramics endure several continuous phase transitions with increasing BNKLZ content, i.e., an orthorhombic phase (0≤x<0.03), orthorhombic–tetragonal phases (x=0.03), orthorhombic–tetragonal and rhombohedral–orthorhombic (O–T and R–O) phase existence (0.03<x≤0.05), a rhombohedral phase (0.05<x≤0.07). The ceramics with O–T and R–O have a better piezoelectric behavior as compared with other phases because of more polarization states, enhanced εr and Pr, and a dense microstructure. Moreover, piezoelectric properties could be further optimized by modifying their sintering and poling temperatures. As a result, the construction of O–T and R–O phase coexistence benefits the improvement of piezoelectric properties in KNN-based ceramics.
Adding both La3+ and Co3+ was used to tune the microstructure and electrical properties of BiFeO3 (BFO) thin films, and Bi1−xLaxFe0.90Co0.10O3 thin films were grown on the SrRuO3-buffered Pt-coated silicon substrates by a radio frequency sputtering. A polycrystalline structure with (110) orientation was shown in thin films, and their resistivity dramatically increases as the La3+ content increases. Their dielectric constant increases, and dielectric loss decreases with increasing La3+ content. In addition, their ferroelectric and fatigue properties were enhanced with rising La3+ content. The thin films with x = 0.03 have optimum electrical properties (e.g., remanent polarization 2Pr ~ 175.6 μC/cm2, coercive field 2Ec ~ 699.5 kV/mm, dielectric constant εr ~ 257 and tan δ ~ 0.038), together with a good fatigue behavior. The impendence analysis of the films was conducted to identify the defects type during conductivity, and both hopping electrons and single-charged oxygen vacancies are mainly responsible for the conduction of grain and grain boundaries regardless of La3+ content. As a result, the doping with both La3+ and Co3+ benefits the improvement in the electrical properties of BFO thin films.
High-performance lead-free piezoelectrics (d33 > 400 pC/N) based on 0.96(K0.5Na0.5)0.95Li0.05Nb1–xSbxO3-0.04BaZrO3 with the rhombohedral-tetragonal (R–T) phase boundary have been designed and prepared. The R-T phase boundary lies the composition range of 0.04 ≤ x ≤ 0.07, and the dielectric and piezoelectric properties of the ceramics with the compositions near the phase boundary are significantly enhanced. In addition, the ceramic with x = 0.07 has a giant d33 of ∼425 pC/N, which is comparable to that (∼416 pC/N) of textured KNN-based ceramics (Saito, Y.; Takao, H.; Tani, T.; Nonoyama, T.; Takatori, K.; Homma, T.; Nagaya, T.; Nakamura, M. Nature 2004, 432, 84). The underlying physical mechanisms for enhanced piezoelectric properties are addressed. We believe that the material system is the most promising lead-free piezoelectric candidates for the practical applications.Keywords: giant d33; lead-free piezoelectrics; potassium−sodium niobate; rombohedral-tetragonal phase boundary;
For potassium–sodium niobate, the piezoelectric constant (d33) was usually improved by sacrificing the Curie temperature (TC). In this work, a material system of 0.992(K0.46Na0.54)0.965Li0.035Nb1–xSbxO3-0.008BiScO3 has been designed and prepared with the aim of achieving both a large d33 and a high TC at the same time. The chemical compositions are found to be homogeneously distributed in the ceramics. The introduction of Sc is found to be responsible for different grain sizes. The rhombohedral-tetragonal phase coexistence zone lies in the composition range of 0.02
A method is used to improve the electrical properties of BiFeO3 thin films by modifying the Bi content in ceramic targets, where all thin films were prepared on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates by radio frequency sputtering. The Bi content in the ceramic target strongly affects the electrical properties of BiFeO3 thin films. BiFeO3 thin films prepared by using the ceramic target of Bi/Fe ≈ 1.15 with a molar ratio demonstrate a low leakage current density and a low dielectric loss. Moreover, a larger remanent polarization of 2Pr ≈ 167.6 μC/cm2 is also demonstrated for the BiFeO3 thin films prepared by using the ceramic target of Bi/Fe ≈ 1.15, together with an improved fatigue behavior. Therefore, it is an effective way to improve the electrical properties of bismuth ferrite thin films by modifying the Bi content in ceramic targets.Keywords: bismuth content; bismuth ferrite; electrical properties;
Migration kinetics of oxygen vacancies in BiFe0.95Mn0.05O3 thin film were investigated by the temperature -dependent leakage current as well as the electric field and temperature-dependent impedance spectroscopy. The BiFe0.95Mn0.05O3 is of an abnormal leakage behavior, and an Ohmic conduction is observed regardless of varied temperatures and electric fields. The temperature-dependent impedance spectroscopy under different resistance states is used to illuminate different leakage behavior between BiFe0.95Mn0.05O3 and pure BiFeO3. The impedance spectroscopy under a high resistance state shows that the first ionization of oxygen vacancies is responsible for the dielectric relaxation and electrical conduction of BiFe0.95Mn0.05O3 in the whole temperature range of 294 to 474 K; the BiFeO3 exhibits similar dielectric relaxation and electrical conduction behavior in the low-temperature range of 294–374 K, whereas the short-range motion of oxygen vacancies was involved in the high-temperature range of 374–474 K. The impedance spectroscopy under a low resistance state demonstrates that the dielectric relaxation and conduction mechanisms almost keep unchanged for BiFe0.95Mn0.05O3, whereas the hopping electrons of Fe2+–VO•–Fe3+ and Fe2+–Fe3+ are responsible for its dielectric relaxation and conduction mechanism of BiFeO3. Different impedance spectroscopy under low and high resistance states confirms that an abnormal leakage behavior of BiFe0.95Mn0.05O3 is related to different migration kinetics of oxygen vacancies, obviously differing from that of BiFeO3.Keywords: bismuth ferrite; ferroelectric properties; impedance spectroscopy; mn; multiferroics; oxygen vacancy;
The ferroelectric behavior of BiFeO3 thin films is modified by changing the film thicknesses, where the BiFeO3 thin films with different thicknesses were grown on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates by radio frequency sputtering. The mixture of (110) and (111) orientations is induced for all BiFeO3 thin films regardless of their thicknesses, together with the columnar structure and the dense microstructure. Their dielectric behavior is almost independent of the film thickness where all thin films have a low dielectric loss. A giant remanent polarization of 2Pr ≈ 156.6–188.8 μC/cm2 is induced for the BiFeO3 thin films in the thickness range of 190–600 nm. As a result, it is an effective way to improve the ferroelectric behavior of the BiFeO3 thin film by tailoring the film thickness.Keywords: bismuth ferrite; ferroelectric properties; thickness dependence;
Ferroelectric and fatigue behavior of bilayered thin films consisting of Mn4+-modified BiFeO3 and Zn2+-modified BiFeO3, which were deposited on SrRuO3-buffered Pt coated silicon substrates, were systematically investigated. The (1 1 1) orientation is induced for the BiFe0.95Mn0.05O3/BiFe0.95Zn0.05O3 bilayer, due to the introduction of the bottom BiFe0.95Zn0.05O3 layer. With increasing the thickness ratio of the BiFe0.95Mn0.05O3 layer, their leakage current decreases, and the fatigue endurance is greatly improved owing to the introduction of the BiFe0.95Mn0.05O3 layer with a lower fatigue rate. The BiFe0.95Mn0.05O3/BiFe0.95Zn0.05O3 bilayer with the thickness ratio of 3:1 exhibits a larger remanent polarization of 2Pr ∼ 161.0 μC/cm2 than those of bilayers with different thickness ratios, while their coercive field slightly increases with increasing the thickness ratio of the BiFe0.95Mn0.05O3 layer.
Co-reporter:Jing Lv, Hui Zhao, Ming Wu, Xiaojie Lou, Jiagang Wu
Materials & Design (5 July 2017) Volume 125() pp:213-221
Publication Date(Web):5 July 2017
DOI:10.1016/j.matdes.2017.04.007
•Defective BFO-based ceramics with a low leakage current density were fabricated.•Attaining a giant remnant polarization (2Pr ~ 90-119 μC/cm2) in BFO–based ceramics by optimizing defect-dipoles.•An enhanced tunable magnetization (Mr = 0.022 ~ 0.038 emu/g) were measured.In this work, the electric and magnetic properties of BiFeO3 (BFO) ceramics are modulated by changing the defect-dipoles using different Bi2O3 contents, where excessive Bi2O3 gives rise to the formation of iron (VFe) and oxygen (VO) vacancies and Bi2O3 deficiency mainly leads to the formation of bismuth (VBi) and oxygen vacancies (VO). It is of great interest to note that a rather low leakage current density can be achieved in both Bi2O3 deficient and excessive ceramics. We also find that a moderate level of Bi2O3 deficiency (< 9%) has little influence on d33. Surprisingly, Bi2O3 excess, widely used for fabricating BFO ceramics with better properties in the past, cannot improve d33. An enhanced piezoelectricity (d33 = 49–51 pC/N) can be obtained in the BFO ceramics with a wide Bi2O3 content range (i.e., x = − 0.09–0.09). A large remanent polarization (2Pr ~ 90–119 μC/cm2) and a tunable magnetization (Mr = 0.022–0.038 emu/g and Hc = 0.87–4.04 kOe) are achieved in BFO ceramics with x = − 0.15–0.15. These defect-dipoles induced by Bi2O3 deficiency or excess can well modulate the electric and magnetic properties of BiFeO3 ceramics.Download high-res image (154KB)Download full-size image
Journal of Materials Chemistry A 2016 - vol. 4(Issue 25) pp:NaN6151-6151
Publication Date(Web):2016/05/23
DOI:10.1039/C6TC01629D
Multiferroic bismuth ferrite (BiFeO3, BFO) is one of the most promising high-temperature ferroelectric and piezoelectric materials due to a high Curie temperature (TC ∼ 825 °C) if the enhancement of ferroelectricity and piezoelectricity can be realized. Unfortunately, it is difficult to adequately pole BFO ceramics due to a high coercive field as well as a high leakage current. Here we investigated the defect dipole-induced poling characteristics and the ferroelectric properties of four kinds of A or/and B-doped BFO ceramics (i.e. BiFeO3, Bi0.95Sm0.05FeO3, BiFe0.95Sc0.05O3, and Bi0.95Sm0.05Fe0.95Sc0.05O3) using a modified quenching technique. The piezoelectric effect is determined by the poling condition, and moreover the poling behavior is strongly dependent on the ion substitution types of BFO ceramics. An enhanced piezoelectric property (d33 = 46–51 pC N−1) can be attained without the involvement of a phase boundary. Specifically, the doping with Sm (Bi0.95Sm0.05FeO3) can cause an obvious threshold during poling, and additionally Bi0.95Sm0.05FeO3 and Bi0.95Sm0.05Fe0.95Sc0.05O3 components can be curiously adequately poled below the coercive field at the poling temperature of 100 °C. In addition, the saturated P–E loops with an obvious internal bias field (Ei) were observed, where Ei was induced by defect dipoles , and then defect dipoles may be decoupled at 120 °C and 6 kV mm−1 (DC field), resulting in a cyclical poling current. It is of great interest to note that an enhanced remanent polarization (2Pr ∼ 50–60 μC cm−2) of the ceramics is obtained, and especially the internal bias fields can be alleviated by AC-cycling or decreasing the measurement frequency. Finally, we believe that our research will have a significant importance in the improvement of piezoelectricity of BFO-based ceramics.
In this work, we elucidate the influence of Bi0.5Li0.5ZrO3 (BLZ) content on the phase structure, microstructure, and electrical properties of (1 − x)K0.40Na0.60Nb0.965Sb0.035O3–xBi0.5Li0.5ZrO3 lead-free ceramics. We simultaneously achieved a giant d33 and a high TC in this material system. The coexistence of rhombohedral and tetragonal phases is responsible for such a large d33 in the ceramics with BLZ contents (x) ranging from 0.025 to 0.035. Doping with BLZ not only induces the formation of the phase boundary, but also maintains a high TC. The ceramic with x = 0.03 shows an enhanced piezoelectric behaviour (d33 ∼ 400 pC N−1 and kp ∼ 0.47) together with a high TC of 292 °C. A good temperature stability for ferroelectricity and piezoelectricity is also observed in these ceramics. This study is the first time that such a good comprehensive performance has been obtained in potassium–sodium niobate materials. We believe that this type of material system possessing giant-d33 and high-TC is a promising candidate for use in high-temperature piezoelectric devices.
Co-reporter:Xiaojing Cheng, Zhenwei Li and Jiagang Wu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 11) pp:NaN5810-5810
Publication Date(Web):2015/01/28
DOI:10.1039/C5TA00141B
The appearance of colossal permittivity (CP) materials broadens the choice of materials for energy-storage applications. Here we report colossal permittivity in ceramics of TiO2 co-doped with niobium and trivalent cation {i.e., (A0.5Nb0.5)xTi1−xO2, A = Bi, Pr, Dy, Sm, Gd, Yb, Ga, Al or Sc}, in particular in the (Bi0.5Nb0.5)xTi1−xO2 ceramic system that was selected as a candidate material. A very large dielectric constant (εr ∼ 4.2 × 104) and a low dielectric loss (tanδ ∼ 8.3%) were observed for (Bi0.5Nb0.5)xTi1−xO2 ceramics when measured at 1 kHz. Moreover, the addition of Bi and Nb can enhance the temperature stability (between −125–200 °C) and frequency stability (between 102 to 106 Hz) of εr and tanδ. The electron-pinned defect-dipoles are considered to be responsible for both their high εr and low tanδ, which is consistent with changes of valence states determined by X-ray photoelectron spectroscopy. We believe that the TiO2 ceramics as a CP material constitute one of the most promising candidates for high-energy-density storage applications.
Journal of Materials Chemistry A 2015 - vol. 3(Issue 31) pp:NaN15961-15961
Publication Date(Web):2015/06/16
DOI:10.1039/C5TA03511B
In this work, we confirmed the electric-induced transition (EPT) in (K,Na)NbO3-based ceramics through experiment and theory. Through in situ X-ray diffraction measurements, electric field-induced phases (EPs) could be observed in the ceramics. To explain the appearance of EPs, a new function λ(Eex) was introduced into the six order Devonshire theory when the external electric field was applied. Further studies indicate that EPT had two possible forms, i.e., tetragonal-electric induced phase transition (T-EP) and rhombohedral-electric induced phase transition (R-EP), and T-EP plays a more positive role than R-EP in terms of the piezoelectric response. Also, a giant piezoelectricity (d33 = 435–490 pC N−1), a high Curie temperature (TC = 205–234 °C), and a converse piezoelectric coefficient (d*33 = 500–890 pm V−1) can be achieved by choosing optimum metal oxides as well as their content. We believe that such work could help to further study the physical mechanisms of giant piezoelectricity in potassium–sodium niobate.
Journal of Materials Chemistry A 2015 - vol. 3(Issue 43) pp:NaN11334-11334
Publication Date(Web):2015/09/28
DOI:10.1039/C5TC02203G
Poor piezoelectric activity is often observed in BiFeO3 ceramics due to their low resistivity and high coercive field, which can easily result in piezoelectric breakdown before the domains are switched. Here, we attained a high piezoelectricity using a series of bismuth ferrite ceramics substituted by rare earth elements and transition metal elements {e.g., Bi0.925La0.05A0.025FeO3, A: Sm, Yb, Ho, Y, Nd, Pr, Dy, Gd; Bi0.925La0.05Sm0.025Fe0.95M0.05O3, M: Sc, In, Al, Ga, Ni, Co} fabricated using the conventional solid-state method. The influences of site engineering (e.g., Bi site or Fe site) as well as the doped element types on their phase structure, microstructure, and electrical properties have been comparatively analyzed. The ions (e.g., A = Sm, Yb, Ho, and Y) substituting at the Bi site are helpful to attain both a pure phase structure and a relatively good piezoelectricity (d33 ≥ 40 pC N−1) for BFO ceramics, while ion substitutions at the Fe site cannot suppress the formation of impurity phases which results in degraded electrical properties. Both XRD and backscattered electron images fully confirmed the existence of impurity phases (Bi-rich and Fe-rich counterparts) in the ceramics doped by Ga. According to the related experiments, the piezoelectric properties of bismuth ferrite ceramics can be promoted by site engineering as well as the optimization of the element types. This result will point out a way for us to promote the piezoelectric properties of bismuth ferrite ceramics through choosing both suitable doping elements and eliminating impurity phases.
Co-reporter:Ting Zheng, Jiagang Wu, Xiaojing Cheng, Xiaopeng Wang, Binyu Zhang, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang and Xiaojie Lou
Journal of Materials Chemistry A 2014 - vol. 2(Issue 41) pp:NaN8803-8803
Publication Date(Web):2014/09/22
DOI:10.1039/C4TC01533A
We have attained both large piezoelectricity and high strain in (1 − x)(K0.40Na0.60)(Nb0.955Sb0.045)O3–xBi0.50Na0.50ZrO3 [(1 − x)KNNS–xBNZ] lead-free ceramics by forming a rhombohedral (R) and tetragonal (T) phase boundary. The ceramics with 0.035 < x < 0.05 possess R and T phases' coexistence. A large d33 value of ∼450 pC N−1 has been attained when the x value reached 0.04 owing to the involved R–T phase boundary, which is higher with respect to d33 ∼ 416 pC N−1 of textured (K,Na,Li)(Nb,Ta,Sb)O3 ceramics reported by Saito et al. [Nature, 2004, 432, 84]. In addition, it is worth noting that such a ceramic simultaneously possesses a high electric field-induced strain (0.2%) under a low driving electric field of ∼2 kV mm−1, and its Smax/Emax value is equal to be 1071 pm V−1. As a result, we can believe that the (1 − x)KNNS–xBNZ ceramics will become one of the promising material systems in the practical applications of electrical devices.
Journal of Materials Chemistry A 2015 - vol. 3(Issue 35) pp:NaN9216-9216
Publication Date(Web):2015/08/03
DOI:10.1039/C5TC01659B
In this study, colossal permittivity (CP) (104–105) is attained in the (Sm0.5Ta0.5)xTi1−xO2 ceramics, and their dielectric loss can be further decreased by doping oxides and optimizing the sintering temperatures. The effects of Sm and Ta as well as the oxides on their microstructure, dielectric properties, and stability were studied in detail. The secondary phases were induced by doping excessive Sm and Ta, and then both backscattering and EDS confirmed that excessive Sm and Ta result in the generation of secondary phases. The relationships between secondary phases and dielectric properties were established. The formation of secondary phases decreases their dielectric constant, whereas their dielectric loss can be slightly decreased through the optimization of Sm and Ta content. In addition, all the ceramics possess an improved frequency (102–106 Hz) and temperature (−150–200 °C) stability of dielectric properties. Moreover, the addition of oxides containing trivalent (Bi3+) or pentavalent (Sb5+ and Nb5+) elements can further reduce their dielectric loss. Through the results of XPS, the formation of defect-dipole clusters, e.g., and Ta5+Ti3+ATi (A = Ti3+/Sm3+/Ti4+), induced by Sm and Ta should be mainly responsible for enhanced dielectric properties.
Journal of Materials Chemistry A 2015 - vol. 3(Issue 15) pp:NaN3693-3693
Publication Date(Web):2015/02/18
DOI:10.1039/C5TC00363F
We have developed a high-temperature bismuth ferrite ceramics with enhanced piezoelectric activity by chemical modifications, that is, the Bi1−x−ySmxLayFeO3 (0 ≤ x ≤ 0.30 and 0 ≤ y ≤ 0.15) lead-free ceramics were prepared by a conventional solid-state method. The influences of La and Sm content on their microstructure and electrical properties were systematically investigated. The ceramics with 0 ≤ x < 0.10 (y = 0.05) or 0 ≤ y ≤ 0.15 (x = 0.025) belong to a triclinic phase, and a mixed structure with rhombohedral-like and orthorhombic phases was found in the ones with 0.10 ≤ x ≤ 0.30 (y = 0.05). The electrical properties of the ceramics can be operated by refining the x and y values. A very low dielectric loss (tanδ ∼ 0.43%) was shown in the ceramics with x = 0.025 and y = 0.05 because of the involvement of low defect concentrations. In addition, the ceramics with x = 0.025 and y = 0.05 also possess a high piezoelectric activity (d33 ∼ 50 pC N−1), which is larger with the respect to the previously reported results in high-temperature piezoceramics with a Curie temperature of >600 °C, and a better thermal stability of piezoelectricity in 20–700 °C is also shown. We believe that this material system is suitable for high-temperature piezoelectric applications.
Co-reporter:Jin-Song Zhou, Ke Wang, Fang-Zhou Yao, Ting Zheng, Jiagang Wu, Dingquan Xiao, Jianguo Zhu and Jing-Feng Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 34) pp:NaN8787-8787
Publication Date(Web):2015/07/14
DOI:10.1039/C5TC01357G
Growing environmental concerns are pushing the development of lead-free piezoceramics with both outstanding piezoelectric properties and reasonable thermal stability. Herein, we realized a large piezoelectric coefficient d33 of 430 pC N−1 in 0.96(K0.4Na0.6)(Nb0.96Sb0.04)O3–0.04Bi0.5K0.5Zr0.85Sn0.15O3 (KNNS–BKZS) polycrystals by constructing a rhombohedral–tetragonal (R–T) phase boundary. Investigations of the in situ thermal stability of the piezoelectric properties on multiple scales reveal that the micro-scale piezoelectric response is much more stable compared to the macro-scale response, indicating the significant role of extrinsic contributions from domain wall movements. These findings demonstrate the relationship between multi-scale properties and domain structures, revealing that the high piezoelectricity is attributed to nano-domains at the R–T phase boundary.
Journal of Materials Chemistry A 2014 - vol. 2(Issue 12) pp:NaN4126-4126
Publication Date(Web):2014/02/12
DOI:10.1039/C3TA15075E
To protect the environment and human health, it is necessary to develop high-performance lead-free piezoceramics to replace the lead-based ones in some electronic devices. Here we report first a large piezoelectricity in (K,Na)NbO3-based lead-free piezoceramics prepared by the conventional solid-state method. The rhombohedral–tetragonal phase boundary is observed in the ceramics with a composition of 0.04 ≤ x ≤ 0.06. Those ceramics with 0.01 ≤ x ≤ 0.06 possess a good comprehensive performance of d33 (380–460 pC N−1) and TC (170–287 °C). Moreover importantly, a peak d33 of ∼460 pC N−1 is shown in the ceramic with x = 0.04, which is superior to all other reported results of KNN-based ceramics, including the reported results by Saito et al. (Nature, 2004, 432, 84). We believe that such a material system is a very promising candidate for potassium–sodium niobate piezoceramics.
Journal of Materials Chemistry A 2015 - vol. 3(Issue 13) pp:NaN6780-6780
Publication Date(Web):2015/02/24
DOI:10.1039/C5TA00732A
Here, we report enhanced piezoelectricity over a very wide sintering temperature range (400–1050 °C) in 0.96(K0.4Na0.6)(Nb0.96Sb0.04)O3–0.04Bi0.5K0.5Zr0.9Sn0.1O3 lead-free ceramics prepared by two step sintering. All ceramics fall into the R–T phase boundary at room temperature, and a dense microstructure without serious loss of alkali elements was found in the samples. The enhanced dielectric, ferroelectric, and piezoelectric properties were attained by two step sintering over a wide sintering temperature range of 400–1050 °C. Most interestingly, the enhanced d33 values of 350–400 pC N−1 can be achieved over a wide temperature range of 400–1050 °C, and the temperature gap range of 650 °C is much wider with respect to previous studies by two step sintering. Besides, an enhanced unipolar strain of ∼0.26% (d*33 ∼ 736 pm V−1) can also be attained in the ceramics.
Co-reporter:Ting Zheng, Jiagang Wu, Dingquan Xiao, Jianguo Zhu, Xiangjian Wang and Xiaojie Lou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 5) pp:NaN1874-1874
Publication Date(Web):2014/12/19
DOI:10.1039/C4TA05423G
The obvious conflicts between large piezoelectricity and high strain could be solved by developing new phase boundaries in potassium–sodium niobate materials. Here, we have solved this problem by extensive experimental researches and induced a larger strain as well as a higher piezoelectricity in (K, Na)NbO3. Large converse piezoelectric coefficient (d*33 = 599–1553 pm V−1) and high strain (0.18–0.46%) were achieved, which are the highest values reported to date in potassium–sodium niobate, suggesting that such a system is a promising lead-free candidate for electromechanical actuator applications. In addition, high d33 values of 400–490 pC N−1 have also been attained in the ceramic due to its rhombohedral–tetragonal phase boundary, as well as its composition.
In this work, the rhombohedral (R) and tetragonal (T) phase boundary of the 0.97(K0.4Na0.6)(Nb1−xSbx)O3–0.03Bi0.5Li0.5ZrO3 piezoceramics has been attained in a wide composition range of 0.035 ≤ x ≤ 0.08, and the Sb5+ could simultaneously shrink its TR–O and TO–T. A giant d33 of 380–405 pC N−1 and a TC of 200–292 °C have been observed in the ceramics with the coexistence of both R and T phases. In addition, the ceramics with 0.035 ≤ x ≤ 0.08 also show a good thermal stability of the d33, and an enhanced temperature stability of ferroelectricity could be observed in the ceramic with x = 0.035. As a result, adding the optimum antimony content is an efficient way to promote the electrical properties of potassium–sodium niobate ceramics with the R–T phase boundary.
(1 − x)(K0.48Na0.52)(Nb0.95Ta0.05)O3–xBi0.5(Na0.7K0.2Li0.1)0.5ZrO3 lead-free piezoelectric ceramics with a new type of phase boundary have been designed and fabricated. This phase boundary lies in the compositional range of 0.04 ≤ x ≤ 0.05, and is formed by the coexistence of the rhombohedral, orthorhombic, and tetragonal phases. Interestingly, we found that the ferroelectric, dielectric, and piezoelectric properties of the ceramics with compositions near the phase boundary are significantly enhanced. In particular, the ceramic with x = 0.045 shows the best piezoelectric behavior of d33 ∼ 290 pC/N and kp ∼ 0.42 among all the compositions studied in this work, and it also exhibits a good thermal stability at annealing temperatures of ≤270 °C. All these results indicate that such a material system is a good candidate for lead-free piezoelectric applications in the future.
In this work, we simultaneously achieved a giant d33 and a high TC in a lead-free piezoelectric ternary system of (1 − x − y)K0.48Na0.52NbO3–xBiFeO3–yBi0.5Na0.5ZrO3 {(1 − x − y)KNN–xBF–yBNZ}. Owing to the rhombohedral–orthorhombic–tetragonal (R–O–T) phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramics with a composition of (x = 0.006, y = 0.04) show a giant d33 of ∼428 pC N−1 together with a TC of ∼318 °C, thereby proving that the design of ternary systems is an effective way to achieve both high d33 and high TC in KNN-based materials. In addition, a good thermal stability for piezoelectricity was also observed in these ceramics (e.g., d33 > 390 pC N−1, T ≤ 300 °C). This is the first time such a good comprehensive performance in potassium–sodium niobate materials has been obtained. As a result, we believe that this type of material system with both giant d33 and high TC is a promising candidate for high-temperature piezoelectric devices.
In this work, the two-step sintering technique is used to realize a high piezoelectric constant (d33) and wide sintering temperature range (TS) in the 0.955(K0.42Na0.58)(Nb0.96Sb0.04)O3–0.045(Bi0.5K0.5)0.90Zn0.10ZrO3 lead-free ceramics. Dense microstructures were developed in the ceramics by two-step sintering. In the TS range of 800–1130 °C, the rhombohedral–tetragonal phase boundary was well maintained, and these ceramics possess enhanced dielectric, ferroelectric, and piezoelectric properties. It is of great interest to note that a d33 of 323–416 pC/N could be attained in a temperature gap range of 330 °C. We believe that the two-step sintering could both widen the sintering temperature and obtain a high d33 for this material system.
In this work, (1 − x)(K0.48Na0.52)(Nb0.95−y−zTazSby)O3-xBi0.5(Na0.82K0.18)0.5ZrO3, {abbreviation: KNNST-BNKZ-x-y-z} lead-free piezoceramics were prepared by a conventional solid-state reaction method, and the composition dependence of their phase structures and electrical properties was systematically discussed. Doping with Sb5+, Ta5+, and BNKZ plays an important role on the phase boundaries as well as piezoelectric activity. A three-phase coexistence involving rhombohedral-orthorhombic-tetragonal (R–O–T) phases was observed in the ceramics with 0.0325 ≤ x ≤ 0.05, 0.035 ≤ x ≤ 0.065, 0.05 ≤ z ≤ 0.08, indicating that doping with BNKZ, Ta5+, and Sb5+ can induce the formation of such a phase boundary by simultaneously increasing TR–O and decreasing TO–T. Enhanced piezoelectric behavior was observed in the ceramics located in the composition region of the R–O–T phase boundary, and a high d33 value of 400 pC N−1 can be attained by refining their compositions (e.g., x = 0.0325, y = 0.035, and z = 0.05), together with a high TC value of ∼240 °C. Of particular interest is that a large electric field-induced strain of 0.18% (Smax/Emax = 706 pm V−1) was also found in the ceramics with x = 0.0325, y = 0.035, and z = 0.05 under a low electric field of 2.5 kV mm−1. As a result, the piezoelectric activity as well as the strain can be operated in the material system by refining x, y, and z content.
In this study, we systematically investigated the composition dependence of the phase structure, microstructure, and electrical properties of (Ba0.94Ca0.06)(Ti1–xMx)O3 (M = Sn, Hf, Zr) ceramics synthesised by the conventional solid-state reaction method. The phase boundary type strongly depends on the composition, and then different electrical properties were exhibited. The addition of Hf and Zr can more quickly shift phase transition temperatures (TR–O and TO–T) to a higher temperature with respect to Sn, leading to the formation of different phase boundaries. In addition, different phase boundaries can also be affected by their doped contents. The R–O and O–T phase boundaries can be shown in the Sn-doped ceramics with x = 0.10, and the R–O phase boundary can exist in the Hf (x = 0.07) or Zr (x = 0.075)-doped ceramics. A high piezoelectric property of d33 = 600 pC N−1 can be achieved in the Sn-doped ceramics due to the involvement of converging R–O/O–T phase boundaries, an enhanced ferroelectric performance with Pr = 14.54 μC cm−2 and Ec = 1.82 kV cm−1 can be attained in the Zr-doped ceramics, and Hf would benefit from obtaining a large strain behaviour (∼0.20%). We believe that the electrical properties and the related physical mechanisms of BaTiO3-based ceramics can be well unveiled by studying their chemical modification behavior.
