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Na/K RATIOS DEPENDENCE OF piezoelectric AND FERROELECTRIC properties IN(K_(1-x)Na_(x))TNbO_(3)LEAD-FREE CERAMICS

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Journal of Advanced Dielectrics 2011年第4期1卷 471-478页

作者： HONGLIANG DU SHAOBO QU ZHUO XU XIAOYONG WEI WANCHENG ZHOU DONGMEI ZHU LUO FA The College of Science Air Force Engineering University Xi'an 710051P.R.China Electronic Materials Research Laboratory Key Laboratory of Educational Ministry Xi'an Jiaotong University Xi'an 710049 P.R.China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 P.R.China

In order to clarify the Na/K ratios dependence of piezoelectric properties,(K_(1-x)Na_(x))TNbO_(3)cer-amics were prepared by conventional solid-state sintering at a=0.4-0.6 with a smaller com-positional interval(0.02 mol).The results demonstrate that the Na/K ratios have obvious effecton piezoelectric and ferroelectric properties of(K_(1-x)Na_(x))NbO_(3)*** and fer-roelectric properties show the maximum(d_(33)147 pc/N,k_(p)=0.40,and P_(r)=24μC/cm^(2))at=0.54,which is not consistent with conventional *** reasons should be attributedto the existence of a phase boundary at a=0.54 mol,which is similar to the morphotropic phaseboundary in Pb(Zr,Ti)O_(3)ceramics.

关键词： Lead free piezoelectric ceramics piezoelectric properties morphotropic phase boundary

Effects of Cr_2O_3 doping on the electrical properties and the temperature stabilities of PZT binary piezoelectric ceramics

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Rare Metals 2008年第4期27卷 362-366页

作者： LI Jianhua SUN Qingchi School of Electronic and Information and Engineering Tianjin University Tianjin 300072 China. School of Materials Science and Engineering Tianjin University Tianjin 300072 China

The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. The effects of Cr2O3 doping on the phase structure, the microstructure, and the electrical properties of ceramics were investigated. Meanwhile, the temperature stabilities of the resonant frequency （fx） were studied. The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples. The minimum value （-0.182%） of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃. The values of ε^τ33/ε0 = 1650, tanδ = 0.006, d33 = 328 pC/N, Kp = 0.63, Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%, which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%, 0.4 wt.%, and 0.8 wt.%, but had a similar value as compared with the tmdoped samples. When the Cr2O3 additive increased, the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.

关键词： ceramics piezoelectric properties temperature stability doping

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

Effects of Excess Barium on the Structure and Electrical properties of(Ba,Ca)TiO_3 piezoelectric Ceramics with High Mechanical Quality Factors

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Journal of Wuhan University of Technology(Materials Science) 2018年第5期33卷 1039-1045页

作者： CHEN Lei FAN Huiqing State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University

Manganese-doped Ba（0.925）Ca（0.075）TiO3 lead-free piezoelectric ceramics（abbreviated as BCT）with high mechanical quality factor were synthesized by conventional solid-state reaction *** effects of excess Ba on the crystal structure,microstructure,and electrical properties of the ceramics were systematically investigated.X-ray diffraction and Raman spectra revealed that Ca^2＋ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol%extra Ba^2＋ions were added after *** grain size of the ceramics was decreased by adding extra Ba^2＋*** mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%.High piezoelectric coefficients（d（33）=150-190 pC/N）and high mechanical quality factors（Qm=1 000-1 200）were obtained in the ceramics when the excess of Ba was between 0.5 mol%and 1 mol%.These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba.

关键词： lead-free ceramics excess Ba grain-size effect piezoelectric properties

Modified phase transition and electrical properties of [Li_(0.05)(Na_(0.535)K_(0.48))_(0.95)]- (Nb_(0.94)Sb_(0.06))O_3 lead-free piezoelectric ceramic by sintering temperature

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Rare Metals 2012年第6期31卷 590-594页

作者： Zhao Xiaokun Zhang Boping Zhao Lei Zhu Lifeng Li Yan Cheng Liqian Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Tsinghua Univ State Key Lab New Ceram & Fine Proc Dept Mat Sci & Engn Beijing 100084 Peoples R China

Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.

关键词： lead-free sintering temperature microstructure phase piezoelectric properties piezoelectric ceramic

Fabrication and properties of 1-3 Polymer Modified Cement Based piezoelectric Composites

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Fabrication and Properties of 1-3 Polymer Modified Cement Ba...

BiAlO_(3)-modified BiFeO_(3)-BaTiO_(3) high Curie temperature lead-free piezoelectric ceramics with enhanced performance

The 1st International Congress on Advanced Materials 2011

作者： Mimi Li Min Sun Shifeng Huang Dongyu Xu Yamei Liu School of Material Science and Engineering University of Jinan

A piezoelectric ceramic(lead niobium lithium zirconate titanate, P(LN)ZT), sulphoaluminate cement and polymer were used to fabricate polymer modified cement based piezoelectric composites by cut-filling technique. The influence of P(LN)ZT volume fraction on the piezoelectric and dielectric properties of composite was investigated. The results show that as the P(LN)ZT volume fraction increase, thepiezoelectric strain factor d 33 , relative dielectric factor ε r and the acoustic impedance increase evidently, while the piezoelectric voltage factor g 33 and the dielectric loss tanδ decrease. Comparing with P(LN)ZT piezoelectric ceramic, the vibration at thickness mode of 1-3 type piezoelectric composite is strengthened, and the electromechanical quality factor is reduced. When P(LN)ZT volume fraction is 30.86%, the acoustic impedance value is 8.24 M rayl, which is close to that of the concrete (9.0 M rayl), and this is suitable for the non destructive inspection.

关键词： 1-3 polymer modified cement based piezoelectric composite piezoelectric properties dielectric properties electromechanical properties acoustic impedance

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Rare Metals 2023年第11期42卷 3839-3850页

作者： Xiao-Xiao Zhou Yu-Cheng Tang He-Zhang Li Yi-Jin Hao Meng-Ping Xue Jun Pei Xiao-Yan Peng Bo-Ping Zhang School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China Department of Precision Instrument Tsinghua UniversityBeijing10084China Beijing Key Laboratory of Special Ceramics and Refractories China Iron&Steel Research Institute GroupBeijing100081China

BiFeO_(3)-BaTiO_(3)(BF-BT)lead-free piezoelectric ceramics have high piezoelectricity and high Curie temperature(T_(C)),but the mixed-valence Fe ions and Bi^(3+)volatilization would promote the formation of Bi_(25)FeO_(40)/Bi_(2)Fe_(4)O_9 and oxygen vacancy,which greatly degrade the insulation properties required for *** this study,it was found that the modification of BiAlO_(3)(BA)in BF-BT ceramics could effectively solve these problems,reducing the leakage current to 1×10^(-9)A·cm^(-2)and transiting the space charge-limited conduction to ohmic *** of the enhanced insulation properties and appropriate rhombohedral-pseudocubic phase ratio(C_R/C_(PC)),BF-BT-xBA ceramics in an optimized composition obtain enhanced piezoelectric performance:piezoelectric charge coefficient(d_(33))=196 pC·N^(-1),planar electromechanical coupling coefficient(k_(p))=31.1%,T_(C)=487℃and depolarization temperature(T_d)=250°C;unipolar strain(S_(uni))=0.17%and piezoelectric strain coefficient(d_(33)^(*))=335 pm·V^(-1)at 100℃.Especially,d_(33)exceeds 283 pC·N^(-1)at 233℃and d_(33)^(*)is 335 pm·V^(-1)at100℃,showing an excellent high-temperature piezoelectricity and high depolarization *** results are attributed to the domain structure of rhombohedral-pseudocubic phase coexistence and its high-temperature switching *** work provides a feasible and effective approach to improve the high temperature piezoelectric properties of BF-BT-xBA ceramics,making them more suitable for high temperature applications.

关键词： BiFeO_(3)-BaTiO_(3)(BF-BT) Curie temperature Electrical insulation properties piezoelectric properties Thermal stability

Structural and electrical properties of Nd ion modified lead zirconate titanate nanopowders and ceramics

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Chinese Physics B 2009年第6期18卷 2596-2602页

作者：王大伟张德庆袁杰赵全亮刘红梅王之英曹茂盛 School of Material Science and Engineering Beijing Institute of Technology College of Chemical Engineering Qiqihar University School of Information Engineering Central University for Nationality

A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1-3x/2^NdxZr0.52Ti0.48O3 （PNZT） in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate （PZT）. Especially, the supreme values of piezoelectric constant （d33） and dielectric constant （ε） for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization （Pr） also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions.

关键词： PNZT ferroelectric properties piezoelectric properties sol-gel method

Field-Induced Domain Reorientation and Polarization Rotation of 〈110〉 Oriented Pb（Mg1/3Nb2/3） O3-PbTiO3 Single Crystals

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Chinese Physics Letters 2006年第6期23卷 1596-1599页

作者：陈克丕张孝文方菲 Key Laboratory of Condition Monitoring and Control for Power Plant Equipment (Ministry of Education) North China Electric Power University Beijing 102206 State Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 Department of Engineering Mechanics Tsinghua University Beijing100084

Polarization hysteresis loops, x-ray diffraction and temperature dependent dielectric constant under different electric fields for 〈110〉 oriented 0.7 PMN-0.3 PT crystals are measured. The field-induced phase transition and the process of depolarization are discussed. The results show that with the electric field E increasing, the singlecrystal form changes from the relaxor state of rhombohedral to normal rhombohedral, then to a monoclinic state via polar-axis reorientation and polarization rotation. Orthorhombic phase may present when E≥ 10 k V, but it is an unstable form after E removal. The depolarization process is not just the reversal of the polarization process. It is noticed that only the temperature-dependent dielectric behaviour is not enough to judge the processes of the E-field induced phase transition.

关键词： piezoelectric properties FERROELECTRIC PHASE