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Tadashi Takenaka - One of the best experts on this subject based on the ideXlab platform.

  • lead free Piezoelectric Ceramics
    Handbook of Advanced Ceramics (Second Edition)#R##N#Materials Applications Processing and Properties, 2013
    Co-Authors: Tadashi Takenaka
    Abstract:

    In the early twenty-first century, Lead-Free Piezoelectric materials have been attracting attention worldwide as new materials in place of PZT-based Piezoelectric Ceramics because of the legislation in the EU.

  • current developments and prospective of lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2008
    Co-Authors: Tadashi Takenaka, Hajime Nagata, Yuji Hiruma
    Abstract:

    The dielectric, ferroelectric and Piezoelectric properties of perovskite ferroelectric and bismuth layered-structured ferroelectric (BLSF) Ceramics are described being superior candidates for Lead-Free Piezoelectric materials to reduce environmental damage. Perovskite-type Ceramics seem to be suitable for actuator and high-power applications that require a large Piezoelectric constant, d33, and a high Curie temperature, Tc, or a depolarization temperature, Td (>200 °C). For BaTiO3-based solid solutions, (1-x)BaTiO3–x(Bi0.5K0.5)TiO3 (BT–BKT100x) Ceramics, Tc increases with increasing amount of x. The BT–BKT20 + MnCO3 (0.1 wt %) ceramic shows a high Tc greater than 200 °C and an electromechanical coupling factor of k33 =0.35. In the case of a(Bi1/2Na1/2)TiO3–b(Bi1/2K1/2)TiO3–cBaTiO3 [BNBK (100a/100b/100c)] solid solution Ceramics, d33 is 191 pC/N for BNBK (85.2/2.8/12). KNbO3 (KN)-based Ceramics are also a candidate for Lead-Free Piezoelectrics. In Mn-doped KN Ceramics, a higher k33 of 0.507 is obtained for KN + MnCO3 (0.1 wt %). On the other hand, BLSF Ceramics seem to be excellent candidates as Piezoelectric sensors for high temperatures and ceramic resonators with a high mechanical quality factor, Qm, and a low temperature coefficient of resonance frequency, TC-f. The k33 value of the donor (Nb)-doped and grain-oriented (HF) Bi4Ti3-xNbxO12 (BITN-x) ceramic is 0.39 for x=0.08 and is able to keep the same stable value up to 350 °C. Nd(0.01) and V(0.75) co-doped Bi4Ti3O12 Ceramics, BNTV(0.01, 0.75), show a relatively low TC-f. Bi3TiTaO9 (BTT)-based solid solution, Srx-1Bi4-xTi2-xTaxO9 [SBTT2(x)] (1x2), displays the high Qm value (=13500) in (p)-mode at x=1.25. For resonator applications, (Sr1-xCax)2Bi4Ti5O18 (SCBT) (0x0.5) Ceramics are suitable.

  • phase transition temperatures and Piezoelectric properties of bi1 2na1 2 tio3 bi1 2k1 2 tio3 batio3 lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2006
    Co-Authors: Yuji Hiruma, Hajime Nagata, Tadashi Takenaka
    Abstract:

    The phase transition temperatures of x(Bi1/2Na1/2)TiO3–y(Bi1/2K1/2)TiO3–zBaTiO3) [x+y+z=1, y:z=2:1] [abbreviate to BNBK2:1(x)] Ceramics were investigated using electrical measurements. We discussed the determination of the depolarization temperature, Td, and defined the Td for (Bi1/2Na1/2)TiO3 (BNT)-based solid solutions. We also determined the rhombohedral–tetragonal phase transition temperatures, TR–T, for BNBK2:1(x), and verified them using dielectric and Piezoelectric measurements. It was demonstrated that TR–T corresponded with Td at x=0.94. The existence of an intermediate phase with ferroelectric and antiferroelectric properties at temperatures higher than the Td around the morphotropic phase boundary (MPB) was also revealed.

  • electrical properties and depolarization temperature of bi1 2na1 2 tio3 bi1 2k1 2 tio3 lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2006
    Co-Authors: Kazushige Yoshii, Hajime Nagata, Yuji Hiruma, Tadashi Takenaka
    Abstract:

    The Piezoelectric properties of a solid solution of the binary system, x(Bi1/2Na1/2)TiO3–(1-x)(Bi1/2K1/2)TiO3 [BNKT100x; x=0.50–0.98] were investigated, focusing on depolarization temperature, Td. Fine Piezoelectric properties in Lead-Free Piezoelectric Ceramics were obtained near the morphotropic phase boundary (MPB) composition between the rhombohedral and tetragonal structures, and the highest electromechanical coupling factor, k33, and Piezoelectric constant, d33, were 0.56 for BNKT84 and 157 pC/N for BNKT80, respectively. However, the Td of BNKT80 was low (174 °C). The Td of the MPB composition was low, and the Td near the MPB composition was sharply decreased. It is thought that BNKT70 is a candidate composition for Lead-Free actuator applications owing to its relatively large Piezoelectric constant, d33 (126 pC/N), dynamic d33 (214 pm/V), and high depolarization temperature, Td (206 °C). In this study, we determined depolarization temperature, Td, from the temperature dependence of dielectric and Piezoelectric properties.

  • bi1 2na1 2 tio3 bi1 2k1 2 tio3 batio3 based lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2005
    Co-Authors: Yoichi Makiuchi, Hajime Nagata, Yuji Hiruma, Rintaro Aoyagi, Tadashi Takenaka
    Abstract:

    The Piezoelectric properties of Lead-Free x(Bi1/2Na1/2)TiO3-y(Bi1/2K1/2)TiO3-zBaTiO3 [BNBKy:z(x); y:z = 4:1 and 2:1, x+y+z=1] with tetragonal compositions were investigated, focusing on the secondary phase transition T2 from the ferroelectric to antiferroelectric phases. Although the T2 temperatures of BNBK near the MPB composition remained at about 115°C, T2 rapidly shifted to a higher temperature of 200°C or higher for the off-MPB composition [x≤0.75 for BNBK4:1(x) and x≤0.78 for BNBK2:1(x)]. The Piezoelectric activities of off-MPB compositions decreased with decreasing the amount (x) of BNT. The larger Piezoelectric constant d33=135 pC/N, the higher secondary phase transition temperature T2=197°C, and the coupling factor k33=0.45 with a good temperature dependence were obtained for BNBK2:1(0.78).

H. L. W. Chan - One of the best experts on this subject based on the ideXlab platform.

  • structure and electrical properties of bi0 5na0 5tio3 batio3 bi0 5li0 5tio3 lead free Piezoelectric Ceramics
    Solid State Ionics, 2008
    Co-Authors: K W Kwok, H. L. W. Chan
    Abstract:

    Abstract Lead-Free Ceramics (1–x–y)Bi0.5Na0.5TiO3–xBaTiO3–yBi0.5Li0.5TiO3 have been prepared by a conventional ceramic technique, and their structure and electrical properties have been studied. The results of XRD measurement show that Ba2+ and Li+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. With x increasing from 0.02 to 0.12, the Ceramics transform gradually from rhombohedral phase to tetragonal phase and consequently a morphotropic phase boundary (MPB) exists at x = 0.06–0.10, while the concentration of Li+ has no obvious influence on the crystal structure. The substitutions of Ba2+ and (Bi0.5Li0.5)2+ for (Bi0.5Na0.5)2+ in the A-sites of Bi0.5Na0.5TiO3 lower greatly the coercive field Ec and increase the remanent polarization Pr of the Ceramics. Because of the MPB and strong ferroelectricity (lower Ec and large Pr), the Piezoelectricity of the Ceramics is enhanced significantly. For the Ceramics near the MPB (x = 0.06 and y = 0.025–0.10), Piezoelectric coefficient d33 = 152–208 pC/N and planar electromechanical coupling factor kP = 30.8–36.8%. The Ceramics exhibit relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The depolarization temperature Td shows a strong dependence on the concentration x of BaTiO3 and reaches the lowest values near the MPB. The temperature dependences of ferroelectric and dielectric properties suggest that the Ceramics may contain both the polar and non-polar regions at temperatures above Td.

  • structure dielectric and Piezoelectric properties of cuo doped k0 5na0 5nbo3 batio3 lead free Ceramics
    Journal of Applied Physics, 2007
    Co-Authors: K W Kwok, H. L. W. Chan
    Abstract:

    Lead-Free Piezoelectric Ceramics (1−x)K0.5Na0.5NbO3+xBaTiO3+ymol% CuO have been fabricated by an ordinary sintering technique. Our results show that the doping of CuO is effective in promoting the densification of the Ceramics. With the doping of CuO, all the Ceramics can be well sintered and exhibit a dense, pure perovskite structure. After the formation of a solid solution with BaTiO3, both the paraelectric cubic–ferroelectric tetragonal and ferroelectric tetragonal–ferroelectric orthorhombic phase transition temperatures decrease and a relax behavior is induced. Coexistence of the orthorhombic and tetragonal phases is formed in the Ceramics with 0.04⩽x⩽0.06 and y=1.00 at room temperature. Because of the more possible polarization states arising from the coexistence of the two phases and the improved densification, the Piezoelectric and dielectric properties of the Ceramics are enhanced significantly. The ceramic with x=0.06 and y=1.00 exhibits the optimum properties: d33=193pC∕N, kp=0.43, kt=0.40, and ...

  • structure and electrical properties of k0 5na0 5nbo3 lisbo3 lead free Piezoelectric Ceramics
    Journal of Applied Physics, 2007
    Co-Authors: K W Kwok, H. L. W. Chan
    Abstract:

    Lead-Free PiezoelectricCeramics ( 1 − x ) K 0.5 Na 0.5 Nb O 3 – x Li Sb O 3 have been fabricated by a conventional Ceramicsintering technique. The results of x-ray diffraction suggest that Li + and Sb 5 + diffuse into the K 0.5 Na 0.5 Nb O 3 lattices to form a solid solution with a perovskite structure. The Ceramics can be well sintered at 1070 – 1110 ° C . The introduction of Li Sb O 3 into the Na 0.5 K 0.5 Nb O 3 solid solution decreases slightly the paraelectric cubic-ferroelectric tetragonal phase transition temperature ( T c ) , but greatly shifts the ferroelectric tetragonal-ferroelectric orthorhombic phase transition ( T O – F ) to room temperature. Coexistence of the orthorhombic and tetragonal phases is formed at 0.05 < x < 0.07 at room temperature, leading to a significant enhancement of the Piezoelectric properties. For the ceramic with x = 0.06 , the Piezoelectric properties become optimum: Piezoelectric constant d 33 = 212 pC ∕ N , planar and thickness electromechanical coupling factors k P = 46 % and k t = 47 % , respectively, remanent polarization P r = 15.0 μ C ∕ cm 2 , coercive field E c = 1.74 kV ∕ mm , and Curie temperature T C = 358 ° C .

  • ferroelectric and Piezoelectric properties of na1 xbaxnb1 xtixo3 Ceramics
    Journal of the American Ceramic Society, 2006
    Co-Authors: J T Zeng, Kin Wing Kwok, H. L. W. Chan
    Abstract:

    Piezoelectric Ceramics Na1−xBaxNb1−xTixO3 with low BaTiO3 concentrations x have been prepared by the solid-state reaction method, and their ferroelectric and Piezoelectric properties have been studied. The Ceramics are classic ferroelectrics when x≤0.10, and the ferroelectric–paraelectric phase transition becomes diffusive when x≥0.15. A low doping level of BaTiO3 changes the NaNbO3 Ceramics from antiferroelectric to ferroelectric. With the increase in BaTiO3 doping level, the Curie temperature of Ceramics decreases linearly and the remnant polarization and coercive field also decrease, while their dielectric constant increases. Na0.9Ba0.1Nb0.9Ti0.1O3 Ceramics show the largest Piezoelectric constant d33 (147 pC/N) and good sinterability, suggesting that it is a good candidate for Lead-Free Piezoelectric Ceramics.

  • electromechanical and ferroelectric properties of bi1 2na1 2 tio3 bi1 2k1 2 tio3 batio3 lead free Piezoelectric Ceramics
    Applied Physics Letters, 2004
    Co-Authors: X X Wang, X G Tang, H. L. W. Chan
    Abstract:

    Lead-Free Piezoelectric Ceramics (0.95−x)(Bi1∕2Na1∕2)TiO3–x(Bi1∕2K1∕2)TiO3–0.05BaTiO3 (abbreviated as BNT–BKT–BT100x, with x ranged from 0 to 20mol%) have been studied. Effects of amount of BKT on the electrical properties and crystal structure were examined. BNT–BKT–BT5 Ceramics give good performances with Piezoelectric constant d33=148pC∕N, electromechanical coupling factor kp=34%, kt=49.2%, free permittivity e33T∕e0=700, and dissipation factor tanδ=2% at 1kHz. Accordingly, the sample shows larger remanent polarization and lower coercive field than 0.95BNT–0.05BT Ceramics. X-ray diffraction analysis shows that incorporated BKT diffuses into the BNT–BT lattice to form a solid solution during sintering, but changes the crystal structure from rhombohedral to tetragonal symmetry at higher BKT amounts.

Jingfeng Li - One of the best experts on this subject based on the ideXlab platform.

  • poling engineering of k na nbo3 based lead free piezoCeramics with orthorhombic tetragonal coexisting phases
    Journal of Materials Chemistry C, 2017
    Co-Authors: Qi Li, Ke Wang, Maohua Zhang, Jinsong Zhou, Jingfeng Li
    Abstract:

    (K,Na)NbO3 (KNN) is considered as one of the most promising candidates for Lead-Free Piezoelectric Ceramics, due to its large Piezoelectric response as well as high Curie temperature. In the present study, the effect of various poling conditions on CaZrO3-modified KNN-based Lead-Free piezoCeramics was investigated. Featured by a polymorphic phase transition around ambient temperature, the samples differ from conventional Pb(Zr,Ti)O3-based (PZT) Ceramics in phase constitution, which inevitably influences the optimal poling conditions. It is found that the KNN Ceramics can reach a saturated polarization state under reduced poling field and at short times, compared with PZT. Besides, poling at a relatively high temperature of 120 °C can yield an enhanced Piezoelectric constant d33 of up to 345 pC N−1. The poling behavior of CaZrO3-modified KNN-based Ceramics is rationalized by the competition between domain reorientation and space charge accumulation.

  • further enhancing Piezoelectric properties by adding mno2 in agsbo3 modified li k na nb ta o3 lead free piezoCeramics
    Journal of the American Ceramic Society, 2016
    Co-Authors: Lei Zhao, Ke Wang, Longtu Li, Jingfeng Li
    Abstract:

    This work investigated the effect of MnO2 addition on the phase structure, microstructure, and electrical properties of AgSbO3-modified (Li,K,Na)(Nb,Ta)O3 (abbreviated as LKNNT-AS) Lead-Free Piezoelectric Ceramics with an optimized composition endowed with a state of two-phase coexistence. A small amount (0.1 wt%) of MnO2 can significantly further enhance the Piezoelectric property of LKNNT-AS Ceramics, whose Piezoelectric constant d33 and converse Piezoelectric coefficient d33* as well as planar electromechanical coupling factor kp reach 363 pC/N, 543 pm/V, and 0.49, respectively. The temperature stability of Piezoelectricity in MnO2-modified LKNNT-AS samples also improved, which is associated with the more uniform and better thermally stable ferroelectric domains that were revealed by piezoresponse force microscopy.

  • k na nbo3 based lead free piezoCeramics fundamental aspects processing technologies and remaining challenges
    Journal of the American Ceramic Society, 2013
    Co-Authors: Jingfeng Li, Ke Wang, Liqian Cheng
    Abstract:

    Environment-friendly Lead-Free Piezoelectric Ceramics have been studied extensively in the past decade with great progress particularly in systems based on a niobate perovskite compound formulated as (K, Na)NbO3 (abbreviated as KNN). A comprehensive review on the latest development of KNN-based Piezoelectric Ceramics is presented in this article, including the phase structure, property enhancement approaches, and sintering processes as well as the status of some promising applications. The phase structure of KNN was reexamined and associated with the effect of chemical modification on its tetragonal-to-orthorhombic transition. Then, a special focus is placed on the temperature dependence of Piezoelectric properties of KNN-based Ceramics, followed by reviewing the recent approaches devoted to the temperature-stability enhancement. The processing fundamentals related to the sintering of KNN-based Ceramics are also presented with an emphasis on compositional and microstructural control. Finally, this review introduces several industrial attempts of traditional piezoceramic products using KNN-based Ceramics and the studies on some promising application in authors' laboratory.

  • orthorhombic to tetragonal phase transition due to stress release in li ta doped k na nbo3 lead free piezoCeramics
    Journal of The European Ceramic Society, 2012
    Co-Authors: Jiajun Zhou, Jingfeng Li, Xiaowen Zhang
    Abstract:

    XRD and Raman scattering experiments revealed an interesting finding that phase structure changed from orthorhombic to tetragonal symmetry when pulverizing (Li,Ta)-doped (K,Na)NbO3 Lead-Free Piezoelectric Ceramics (sintered body) to powder. Both orthorhombic and tetragonal phases coexist in the Li0.05(Na0.51K0.49)0.95Nb0.80Ta0.20O3.00 (LKNNT) sintered bulk sample at room temperature, but almost only the tetragonal phase is observed in the ground powder. In addition, annealing experiment enhanced the formation of tetragonal phase and improved the temperature stability of Piezoelectricity. It is revealed that the internal stress existing in the LKNNT Ceramics favors the formation of orthorhombic phase, which transfers to tetragonal phase when the stress was released.

  • domain engineering of lead free li modified k na nbo3 polycrystals with highly enhanced Piezoelectricity
    Advanced Functional Materials, 2010
    Co-Authors: Ke Wang, Jingfeng Li
    Abstract:

    Aging and re-poling induced enhancement of Piezoelectricity are found in (K,Na)NbO3 (KNN)-based Lead-Free Piezoelectric Ceramics. For a compositionally optimized Li-doped composition, its Piezoelectric coefficient d33 can be increased up to 324 pC N−1 even from a considerably high value (190 pC N−1) by means of a re-poling treatment after room-temperature aging. Such a high d33 value is only reachable in KNN Ceramics with complicated modifications using Ta and Sb dopants. High-angle X-ray diffraction analysis reveals apparent changes in the crystallographic orientations related to a 90° domain switching before and after the aging and re-poling process. A possible mechanism considering both defect migration and rotation of spontaneous polarization explains the experimental results. The present study provides a general approach towards Piezoelectric response enhancement in KNN-based Piezoelectric Ceramics.

Hajime Nagata - One of the best experts on this subject based on the ideXlab platform.

  • current developments and prospective of lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2008
    Co-Authors: Tadashi Takenaka, Hajime Nagata, Yuji Hiruma
    Abstract:

    The dielectric, ferroelectric and Piezoelectric properties of perovskite ferroelectric and bismuth layered-structured ferroelectric (BLSF) Ceramics are described being superior candidates for Lead-Free Piezoelectric materials to reduce environmental damage. Perovskite-type Ceramics seem to be suitable for actuator and high-power applications that require a large Piezoelectric constant, d33, and a high Curie temperature, Tc, or a depolarization temperature, Td (>200 °C). For BaTiO3-based solid solutions, (1-x)BaTiO3–x(Bi0.5K0.5)TiO3 (BT–BKT100x) Ceramics, Tc increases with increasing amount of x. The BT–BKT20 + MnCO3 (0.1 wt %) ceramic shows a high Tc greater than 200 °C and an electromechanical coupling factor of k33 =0.35. In the case of a(Bi1/2Na1/2)TiO3–b(Bi1/2K1/2)TiO3–cBaTiO3 [BNBK (100a/100b/100c)] solid solution Ceramics, d33 is 191 pC/N for BNBK (85.2/2.8/12). KNbO3 (KN)-based Ceramics are also a candidate for Lead-Free Piezoelectrics. In Mn-doped KN Ceramics, a higher k33 of 0.507 is obtained for KN + MnCO3 (0.1 wt %). On the other hand, BLSF Ceramics seem to be excellent candidates as Piezoelectric sensors for high temperatures and ceramic resonators with a high mechanical quality factor, Qm, and a low temperature coefficient of resonance frequency, TC-f. The k33 value of the donor (Nb)-doped and grain-oriented (HF) Bi4Ti3-xNbxO12 (BITN-x) ceramic is 0.39 for x=0.08 and is able to keep the same stable value up to 350 °C. Nd(0.01) and V(0.75) co-doped Bi4Ti3O12 Ceramics, BNTV(0.01, 0.75), show a relatively low TC-f. Bi3TiTaO9 (BTT)-based solid solution, Srx-1Bi4-xTi2-xTaxO9 [SBTT2(x)] (1x2), displays the high Qm value (=13500) in (p)-mode at x=1.25. For resonator applications, (Sr1-xCax)2Bi4Ti5O18 (SCBT) (0x0.5) Ceramics are suitable.

  • phase transition temperatures and Piezoelectric properties of bi1 2na1 2 tio3 bi1 2k1 2 tio3 batio3 lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2006
    Co-Authors: Yuji Hiruma, Hajime Nagata, Tadashi Takenaka
    Abstract:

    The phase transition temperatures of x(Bi1/2Na1/2)TiO3–y(Bi1/2K1/2)TiO3–zBaTiO3) [x+y+z=1, y:z=2:1] [abbreviate to BNBK2:1(x)] Ceramics were investigated using electrical measurements. We discussed the determination of the depolarization temperature, Td, and defined the Td for (Bi1/2Na1/2)TiO3 (BNT)-based solid solutions. We also determined the rhombohedral–tetragonal phase transition temperatures, TR–T, for BNBK2:1(x), and verified them using dielectric and Piezoelectric measurements. It was demonstrated that TR–T corresponded with Td at x=0.94. The existence of an intermediate phase with ferroelectric and antiferroelectric properties at temperatures higher than the Td around the morphotropic phase boundary (MPB) was also revealed.

  • electrical properties and depolarization temperature of bi1 2na1 2 tio3 bi1 2k1 2 tio3 lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2006
    Co-Authors: Kazushige Yoshii, Hajime Nagata, Yuji Hiruma, Tadashi Takenaka
    Abstract:

    The Piezoelectric properties of a solid solution of the binary system, x(Bi1/2Na1/2)TiO3–(1-x)(Bi1/2K1/2)TiO3 [BNKT100x; x=0.50–0.98] were investigated, focusing on depolarization temperature, Td. Fine Piezoelectric properties in Lead-Free Piezoelectric Ceramics were obtained near the morphotropic phase boundary (MPB) composition between the rhombohedral and tetragonal structures, and the highest electromechanical coupling factor, k33, and Piezoelectric constant, d33, were 0.56 for BNKT84 and 157 pC/N for BNKT80, respectively. However, the Td of BNKT80 was low (174 °C). The Td of the MPB composition was low, and the Td near the MPB composition was sharply decreased. It is thought that BNKT70 is a candidate composition for Lead-Free actuator applications owing to its relatively large Piezoelectric constant, d33 (126 pC/N), dynamic d33 (214 pm/V), and high depolarization temperature, Td (206 °C). In this study, we determined depolarization temperature, Td, from the temperature dependence of dielectric and Piezoelectric properties.

  • bi1 2na1 2 tio3 bi1 2k1 2 tio3 batio3 based lead free Piezoelectric Ceramics
    Japanese Journal of Applied Physics, 2005
    Co-Authors: Yoichi Makiuchi, Hajime Nagata, Yuji Hiruma, Rintaro Aoyagi, Tadashi Takenaka
    Abstract:

    The Piezoelectric properties of Lead-Free x(Bi1/2Na1/2)TiO3-y(Bi1/2K1/2)TiO3-zBaTiO3 [BNBKy:z(x); y:z = 4:1 and 2:1, x+y+z=1] with tetragonal compositions were investigated, focusing on the secondary phase transition T2 from the ferroelectric to antiferroelectric phases. Although the T2 temperatures of BNBK near the MPB composition remained at about 115°C, T2 rapidly shifted to a higher temperature of 200°C or higher for the off-MPB composition [x≤0.75 for BNBK4:1(x) and x≤0.78 for BNBK2:1(x)]. The Piezoelectric activities of off-MPB compositions decreased with decreasing the amount (x) of BNT. The larger Piezoelectric constant d33=135 pC/N, the higher secondary phase transition temperature T2=197°C, and the coupling factor k33=0.45 with a good temperature dependence were obtained for BNBK2:1(0.78).

  • current status and prospects of lead free Piezoelectric Ceramics
    Journal of The European Ceramic Society, 2005
    Co-Authors: Tadashi Takenaka, Hajime Nagata
    Abstract:

    Abstract Dielectric, ferroelectric and Piezoelectric properties of perovskite ferroelectric and bismuth layer-structured ferroelectric (BLSF) Ceramics are described as superior candidates for Lead-Free Piezoelectric materials to reduce environmental damages. Perovskite type Ceramics seem to be suitable for actuator and high power applications that are required a large Piezoelectric constant, d 33 (>300 pC/N) and a high Curie temperature, T c (>200 °C). For BaTiO 3 (BT)-based solid solutions, that is, (1 −  x )BaTiO 3 − x (Bi 0.5 K 0.5 )TiO 3 [BTBK − 100 x ] Ceramics, the T c increases with increasing the amount of x . BTBK-20 + MnCO 3 0.1 wt.% ceramic shows the high T c than 200 °C and the electromechanical coupling factor, k 33  = 0.35. In the case of a (Bi 1/2 Na 1/2 )TiO 3  −  b BaTiO 3  −  c (Bi 1/2 K 1/2 )TiO 3 [BNBK (100 a /100 b /100 c )] solid solution Ceramics, the d 33 and T c are 191 pC/N and 301 °C for the BNBK (85.2/2.8/12), respectively. On the other hand, BLSF Ceramics seem to be excellent candidates as Piezoelectric sensors for high temperatures and ceramic resonators with high mechanical quality factor ( Q m ), and low temperature coefficient of resonance frequency (TC- f r ). Donor-doped Bi 4 Ti 3 O 12 Ceramics such as Bi 4 Ti 3− x Nb x O 12 [BITN- x ] and Bi 4 Ti 3− x V x O 12 [BITV- x ] show high T c than 650 °C. The k 33 value of the grain-oriented (HF) BITN-0.08 ceramic is 0.39 and is able to keep the same value up to 350 °C. Bi 3 TiTaO 9 (BTT)-based solid solution system, Sr x −1 Bi 4− x Ti 2− x Ta x O 9 [SBTT2( x )] (1 ≦  x  ≦ 2), displays the high Q m value (=13500) in (p)-mode at the x  = 1.25 composition.

Dingquan Xiao - One of the best experts on this subject based on the ideXlab platform.

  • high Piezoelectric coefficient of pr2o3 doped ba0 85ca0 15ti0 90zr0 10o3 Ceramics
    Ceramics International, 2012
    Co-Authors: Jiagang Wu, Chaohui Pu, Sha Qiao, Bo Wu, Dingquan Xiao
    Abstract:

    Abstract Pr 2 O 3 -doped Ba 0.85 Ca 0.15 Ti 0.90 Zr 0.10 O 3 (BCTZ- x Pr) Ceramics were prepared by the conventional solid-state method. A tetragonal phase is only observed in these Ceramics, and the introduction of Pr 2 O 3 decreases their sintering temperature without affecting negatively the Piezoelectric constant. Enhanced ferroelectric properties were obtained in these BCTZ- x Pr Ceramics. The ceramic with x =0.06 wt% exhibits a good electrical behavior of d 33 ∼460 pC/N, k p ∼47.6%, e r ∼4638, and tan δ ∼0.015 when sintered at a low temperature of ∼1400 °C. As a result, the BCTZ- x Pr ceramic is a promising candidate for Lead-Free Piezoelectric Ceramics.

  • sintering temperature induced electrical properties of ba0 90ca0 10 ti0 85zr0 15 o3 lead free Ceramics
    Materials Research Bulletin, 2012
    Co-Authors: Dingquan Xiao, Jianguo Zhu, Zhengchun Yang, John Wang
    Abstract:

    Abstract Effects of the sintering temperature on the microstructure and electrical properties of (Ba 0.90 Ca 0.10 )(Ti 0.85 Zr 0.15 )O 3 (BCTZ) Lead-Free Piezoelectric Ceramics have been studied, where these Ceramics were prepared by the conventional oxide-mixed method at varied sintering temperatures from 1300 °C to 1500 °C. These BCTZ Ceramics exhibits a phase transition from a rhombohedral phase to the coexistence of rhombohedral and tetragonal phases with an increase of sintering temperature. With an increase of sintering temperature, their relative density and average grain size gradually increase, and electrical properties are improved greatly. These BCTZ Ceramics sintered at ∼1440 °C have optimum electrical properties: d 33  ∼ 442 pC/N and k p  ∼ 48.9%, making it a promising material for Lead-Free Piezoelectric Ceramics.

  • composition and poling condition induced electrical behavior of ba0 85ca0 15 ti1 xzrx o3 lead free Piezoelectric Ceramics
    Journal of The European Ceramic Society, 2012
    Co-Authors: Jiagang Wu, Dingquan Xiao, Zhengchun Yang, Wenjuan Wu, Qiang Chen, John Wang
    Abstract:

    Abstract Lead-Free (Ba 0.85 Ca 0.15 )(Ti 1− x Zr x )O 3 (BCTZ) Piezoelectric Ceramics were fabricated by normal sintering in air atmosphere. BCTZ Ceramics with x  = 0.10 possess a coexistence of tetragonal and rhombohedral phases at ∼40 °C. The Curie temperature of BCTZ Ceramics decreases with increasing the Zr content. Piezoelectric properties of BCTZ Ceramics are dependent on the poling conditions (i.e., the poling temperature and the poling electric field), and the underlying physical mechanism is illuminated by the phase angle. The BCTZ ( x  = 0.10) ceramic, which locates at the existence of two phases and is poled at E  ∼ 4.0 kV/mm and T p  ∼ 40 °C, exhibits an optimum electrical behavior at a room temperature of ∼20 °C: d 33  ∼ 423 pC/N, k p  ∼ 51.2%, 2 P r  ∼ 18.86 μC/cm 2 , 2 E c  ∼ 0.47 kV/mm, ɛ r  ∼ 2892, and tan  δ  ∼ 1.53%.

  • phase transitions and electrical properties of 1 x k0 5na0 5 nbo3 xbisco3 lead free Piezoelectric Ceramics with a cuo sintering aid
    Physica Status Solidi (a), 2009
    Co-Authors: Xuhai Li, Meng Jiang, Lihua Li, Yu Zhou, Dingquan Xiao
    Abstract:

    (1−x)(K0.5Na0.5)NbO3−xBiScO3 doped with 1 mol% CuO (KNN-BS-Cu-x) Lead-Free Piezoelectric Ceramics were prepared by the solid state reaction technique. With the CuO doping, all the Ceramics can be well sintered at 1090–1150 °C and exhibit a perovskite structure. After the substitution of BiScO3, the polymorphic phase transition (PPT) was shifted to near room temperature; besides, the cubic–tetragonal phase transitions were also shifted to lower temperatures and a relaxor behavior was induced. The ceramic (x = 0.018) with PPT near room temperature exhibited excellent electrical properties (d33 = 224 pC/N, kp = 0.40, and TC = 331 °C). A relatively high mechanical quality factor (288) was also obtained in this particular composition. All these results reveal that KNN-BS-Cu-x Ceramics may become promising candidates for Lead-Free Piezoelectric materials.

  • effects of k content on the dielectric Piezoelectric and ferroelectric properties of 0 95 kxna1 x nbo3 0 05lisbo3 lead free Ceramics
    Journal of Applied Physics, 2008
    Co-Authors: Dingquan Xiao, Yuanyu Wang, Jianguo Zhu
    Abstract:

    The effects of K content on the dielectric, Piezoelectric, and ferroelectric properties of 0.95(KxNa1−x)NbO3−0.05LiSbO3 (0.95KxNN−0.05LS) (x=0.25–0.75) Lead-Free Piezoelectric Ceramics prepared by conventional solid-state sintering were studied. The experimental results show that the dielectric, Piezoelectric, and ferroelectric properties strongly depend on K content in the 0.95KxNN−0.05LS Ceramics. The 0.95KxNN−0.05LS (x=0.40) Ceramics exhibit enhanced electrical properties (d33≈280 pC/N; kp≈49.4%; Tc∼364 °C; To-t=25 °C; er≈1463; tan δ≈2.3%; Pr∼30.8 μC/cm2; Ec∼14.0 kV/cm). The enhanced electrical properties of 0.95KxNN−0.05LS (x=0.40) Ceramics are attributed to the polymorphic phase transition near room temperature. These results show that 0.95KxNN−0.05LS (x=0.40) ceramic is a promising Lead-Free Piezoelectric material.