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Rare Metals 2009年第2期28卷 142-146页

作者： Zhang, Qian Zhang, Boping Zhao, Pei Li, Haitao Zhang, Limin School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-sults indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and densified the microstructure with a decreased grain size. The highest relative density reached more than 90%. The highest piezoelectric dielectric coefficient d33 and planar mode electro-mechanical coupling coefficient kp were 110 pC/N and 19.5%,which were obtained in the NKNT ceramic with 1 mol% Ti. The piezoelectric properties of the NKNT ceramics were enhanced by aging in air for a period of time owing to the compensation of oxygen vacancies.

关键词： lead-free piezoelectric ceramics Ti-doped piezoelectric property dielectric property normal sintering oxygen vacancies

Influence of CeO_2 doping amount on property of BCTZ lead-free piezoelectric ceramics sintered at low temperature

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Journal of Rare Earths 2014年第8期32卷 733-737页

作者：黄新友邢仁克高春华陈志刚 School of Materials Science and Engineering Jiangsu University Jiangsu Province Key Laboratory of High-end Materials

Ba0.85Ca0.15Ti0.9Zr0.1O3 （BCTZ） lead-free piezoelectric ceramics co-doped with CeO2 （x=0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%） and Li2CO3 （0.6 wt.%） were prepared by conventional solid-state reaction method. Influence of CeO2 doping amount on the piezoelectric properties, dielectric properties, phase composition and microstructure of prepared BCTZ lead-free piezoelectric ceramics doped with Li2CO3 were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM） and other analytical methods. The results showed that the sintered temperature of BCTZ lead-free piezoelectric ceramics doped with CeO2 decreased greatly when Li2CO3 doping amount was 0.6 wt.%;a pure perovskite structure of BCTZ lead-free piezoelectric ceramics co-doped with Li2CO3 and CeO2 and sintered at 1050 ℃ could also be obtained. The piezoelectric constant （d33）, the relative permit-tivity （εr） and the planar electromechanical coupling factor （kp） of BCTZ ceramics doped with Li2CO3 increased firstly and then de-creased, the dielectric loss （tanδ） decreased firstly and then increased and decreased at last when CeO2 doping amount increased. The influence of CeO2 doping on the properties of BCTZ lead-free piezoelectric ceramics doped with Li2CO3 were caused by“soft effect”and “hard effect”piezoelectric additive and causing lattice distortion. When CeO2 doping amount （x） was 0.2 wt.%, the BCTZ ceramics doped with Li2CO3 （0.6 wt.%） and sintered at 1050 ℃ possessed the best piezoelectric property and dielectric property with d33 of 436 pC/N, kp of 48.3%,εr of 3650, tanδof 1.5%.

关键词： lead-free piezoelectric ceramics barium calcium zirconate and titanate CeO2 doping rare earths piezoelectric property

Multi-phase structure and electrical properties of Bi_(0.5)Li_(0.5)ZrO_3 doping K_(0.48)Na_(0.56)NbO_3 lead-free piezoelectric ceramics

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Journal of Advanced ceramics 2018年第1期7卷 79-87页

作者： Xiaoyan PENG Boping ZHANG Lifeng ZHU Lei ZHAO Ruixiao MA Bo LIU Xiaodong WANG School of Materials Science and Engineering University of Science and Technology Beijing New Metallurgy Hi-Tech Group Co. Ltd. China Iron & Steel Research Institute Group Hebei Key Lab of Optic-Electronic Information and Materials College of Physics Science & Technology Hebei University

(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3(KNN–x BLZ, x = 0–0.06) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method, and their phase structures and electric properties as well as T_C were systematically investigated. The orthorhombic–tetragonal(O–T) two phases were detected in all(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 ceramics at 0.01 ≤ x ≤ 0.05. Due to the appropriate ratio between O phase and T phase(CO/C T= 45/55), high piezoelectric properties of d 33= 239 pC/N, k_p= 34%, and P_r = 25.23 μC/cm^2 were obtained at x = 0.04. Moreover, a high T_C = 348 ℃ was also achieved in KNN–x BLZ ceramic at x = 0.04. These results indicate that (1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 system is a promising candidate for high-temperature piezoelectric devices.

关键词： lead-free piezoelectric ceramics potassium–sodium niobate (KNN) solid-state sintering multi-phase electrical properties

Microstructures and Electrical Properties of Bi_(0.5)-(Na_(1-x-y)K_xLi_y)_(0.5)TiO_3 lead-free piezoelectric ceramics

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Journal of Wuhan University of Technology(Materials Science) 2010年第3期25卷 361-364页

作者：张菁吕文中 Department of Electronic Science and Technology Huazhong University of Science and Technology

The microstructures and electrical properties of Bi0.5（Na1-x-yKxLiy）0.5TiO3 lead-free piezoelectric ceramics were studied.These ceramics were prepared by conventional ceramic technique.XRD analysis reveals that the ceramics possess almost pure perovskite phase when y≤0.2.The SEM results show that,with more amounts of Li＋,the crystalline grain growing speed is accelerated,and the sintering temperature can effectively be decreased.The measurements of piezoelectric properties indicate that the ceramics with relatively low amount of Li＋ and high amount of K＋ have comparatively large piezoelectricity.The dielectric measurements show that the ceramics have properties like relaxor ferroelectrics and diffuse phase transition（DPT） at Td and Tc,respectively.The results of ferroelectric measurements reveal the system has relatively higher remanent polarization Pr（27.6 μC/cm2） and lower coercive field Ec（37.5 kV/cm）.

关键词： Bi0.5Na0.5TiO3 lead-free piezoelectric ceramics piezoelectric property remanent polarization

Effect of Li content on the microstructure and properties of lead-free piezoelectric(K_(0.5)Na_(0.5))_(1-x)Li_xNbO_3 ceramics prepared by SPS

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Journal of University of Science and Technology Beijing 2008年第3期15卷 314-319页

作者： Pei Zhao Boping Zhang Ke Wang Limin Zhang Hailong Zhang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

lead-free piezoelectric （K0.5sNa0.5）1-xLixNbO3 （x = 0at%-20at%） ceramics were synthesized by spark plasma sintering （SPS） at low temperature and the effects of LiNbO3 addition on its crystal structure and properties were also studied. When the Li content was less than 6at%, a single proveskite phase with the similar structure of （K0.5Na0.5）NbO3 was formed; and a secondary phase with K3Li2Nb5O15 structure was observed in the 6at% 〈 x 〈 20at% compositional range. Furthermore, LiNbO3 existed as the third phase when the Li content was higher than 8at%. The grain sizes increased from 200-500 nm to 5-8 μm when the K3Li2Nb5O15 and LiNbO3 like phases were formed. With increasing Li content, the relative density of the ceramics first decreased from 97% to 93% and then kept constant. The piezoelectric coefficient d33, dielectric constant, and planner electromechanical coupling factor exhibited a decreasing tendency with increasing Li content because of the decrease in density and the formation of the secondary phase such as K3Li2Nb5O15 and LiNbO3. The formation of dense microstructure with a single phase is necessary in improving the properties of the （K0.5Na0.5）1-xLixNbO3 ceramics.

关键词： lead-free piezoelectric ceramics spark plasma sintering crystal structure piezoelectric properties

PROGRESSES AND FURTHER CONSIDERATIONS ON THE RESEARCH OF PEROVSKITE lead-free piezoelectric ceramics

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Journal of Advanced Dielectrics 2011年第1期1卷 33-40页

作者： DINGQUAN XIAO Department of Materials Science Sichuan University Chengdu 610064P.R.China

The research on lead-free piezoelectric ceramics has been one of the importantfields worldwide for years for the sustainable development of the world.In recent years,the author and his group concentrated their work on perovskite lead-free piezoelectric ceramics,especially on(Bi_(1/2)Na_(1/2))TiO_(3)(BNT)-and K_(1/2)Na_(1/2)NbO_(3)(KNN)-based ceramics.In this paper,the researches of the composition design on BNT-and KNN-based lead-free piezoelectric ceramics,the effects of doping on the properties of these ceramics,the study of the temperature stability of these ceramics,and the fabrication technique used in the author's group for these ceramics are reviewed,and the further considerations and some prospects to be resolved in coming years from the viewpoint of the device applications of these ceramics are suggested.

关键词： lead-free piezoelectric ceramics (Bi_(1/2)Na_(1/2))TTiO_(3)(BNT) K_(1/2)Na_(1/2)NbO_(3)(KNN) perovskite structure

Exceptional electrostrain with minimal hysteresis and superior temperature stability under low electric field in KNN-based lead-free piezoceramics

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Journal of Advanced ceramics 2024年第3期13卷 364-372页

作者： Huan Liu Yijin Hao Ziqi Yang Tianyi Feng Bin Su Xin Zhang Mengping Xue Bo-Ping Zhang Jing-Feng Li Beijing Municipal Key Laboratory of New Energy Materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Over the past two decades,(K_(0.5)Na_(0.5))NbO_(3)(KNN)-based lead-free piezoelectric ceramics have made significant progress.However,attaining a high electrostrain with remarkable temperature stability and minimal hysteresis under low electric fields has remained a significant challenge.To address this long-standing issue,we have employed a collaborative approach that combines defect engineering,phase engineering,and relaxation engineering.The LKNNS-6BZH ceramic,when sintered at T_(sint)=1170℃,demonstrates an impressive electrostrain with a d_(33) value of 0.276%and 1379 pm·V^(-1)under 20 kV·cm^(-1),which is comparable to or even surpasses that of other lead-free and Pb(Zr,Ti)O_(3)ceramics.Importantly,the electrostrain performance of this ceramic remains stable up to a temperature of 125℃,with the lowest hysteresis observed at 9.73%under 40 kV·cm^(-1).These excellent overall performances are attributed to the presence of defect dipoles involving V′_(A)-V∙∙_(O) and B′_(Nb)-V∙∙O,the coexistence of R-O-T multiphase,and the tuning of the trade-off between long-range ordering and local heterogeneity.This work provides a lead-free alternative for piezoelectric actuators and a paradigm for designing piezoelectric materials with outstanding comprehensive performance under low electric fields.

关键词： lead-free piezoelectric ceramics temperature stability electrostrain potassium sodium niobate low hysteresis

Large electro-strain signal of the BNT-BT-KNN lead-free piezoelectric ceramics with CuO doping

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Journal of Advanced Dielectrics 2019年第3期9卷 12-18页

作者： Zhi-Hao Zhao Rui-Fang Ge Yejing Dai School of Materials Sun Yat-sen University Guangzhou 510275P.R.China Key Laboratory for Advanced ceramics and Machining Technology of Ministry of Education School of Materials Science and Engineering Tianjin University Tianjin 300072P.R.China

This paper investigates a system of 0.93Bi_(0.5)Na_(0.5)TiO_(3)–0.06BaTiO_(3)–0.01K_(0.5)Na_(0.5)NbO_(3)–xCuO(BNT–BT–KNN–xCuO,x=0-0:04 mol.%)ceramics,which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier.The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics.With the doping of CuO,the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature,resulting in pinched P–E loops and“sprout”shape S-E curves.For the composition with x=0.01,a high unipolar strain of 0.39%under 5 kV/mm contributes a large d^(*)33~780 pm/V at room temperature,which is competitive with the other BNT-based ceramics.

关键词： lead-free piezoelectric ceramics BNT-based CuO dopant electro-strain

INFLUENCE OF Co2O3 DOPED AMOUNT ON THE PROPERTIES OF(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free piezoelectric ceramics

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INFLUENCE OF Co2O3 DOPED AMOUNT ON THE PROPERTIES OF(Ba0.85C...

INFLUENCE OF BARIUM CONTENT ON THE PROPERTIES AND STRUCTURE OF LOW TEMPERATURE SINTERED BCZT lead-free piezoelectric ceramics

2012全国压电和声波理论及器件技术研讨会

作者： Xin-you HUANG Chun-hua GAO Zhi-wen ZHU Li PAN Zhi-gang CHEN School of Materials Science and Engineering Jiangsu University

The influence of CoO doped amount on dielectric and piezoelectric properties of(BaCa)(ZrTi)O(BCZT)lead-free piezoelectric ceramics was studied by scanning electron microscope(SEM) and X-ray diflraction(XRD) and other analytical methods and conventional solid state method.TiO was chemically pure raw materials,other raw materials were analytical pure raw materials.The results showed that Perovskite structure of BCZT lead-free piezoelectric ceramics did not change when doped with CoO,the intensity of diffraction peaks of BCZT increased first and then decreased,the grain crystal size of ceramics increased first and then decreased,the density of ceramics increased first and then decreased when CoO doped amount increased.The microstructure of ceramics was the best when CoO doped amount was 0.40 wt.%.This was also reason for the good piezoelectric properties.The piezoelectric properties(d,kp,k) of BCZT lead-free piezoelectric ceramics increased first and then decreased,the relative dielectric constant(ε) decreased,dielectric loss increased first and then decreased when CoO doped amount increased.The comprehensive performance of BCZT lead-free piezoelectric ceramics was optimum when CoO doped amount was 0.40 wt.%which piezoelectric strain constant(d) was 171pC/N,relative dielectric constant(ε) was 22400,planar electromechanical coupling coefEcient(k)was 0.478,dielectric loss was 0.018,electromechanical coupling coefficient of thickness(k) was 0.041,sintered temperature was 1340℃.

关键词： lead-free piezoelectric ceramics Barium calcium zirconate and titanate Co2O3 Doped modification

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INFLUENCE OF BARIUM CONTENT ON THE PROPERTIES AND STRUCTURE ...