Study on the Pressureless Sintering and Properties of (K0.5Na0.5)1-xLixNb1-yTayO3 Lead-Free Piezoelectric Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1403-1407
Author(s):  
Hang Fei Hao ◽  
Guo Qiang Tan ◽  
Peng Xiong ◽  
Bo Qin ◽  
Hui Jun Ren

Potassium sodium niobate ((K0.5Na0.5)1-xLixNb1-yTayO3) powers were prepared by solid phase synthesis and (K0.5Na0.5)1-xNb1-yTayO3 lead-free piezoelectric ceramics were fabricated by the pressuerless sintering. The relationship among the powder phase composition and electric properties was studied. The results show that when x=0.5, the sintering temperature is 1050°C,and the polarization voltage is 3 kV/mm, the (K0.5Na0.5)1-xLixNb1-yTayO3 piezoelectric ceramics with the better piezoelectric properties are prepared. (The relative density is 94%, the piezoelectric constant d33=105pC/N, the planar electro-mechanical coupling coefficient kp=0.39, the medium loss tanδ=0.29, the mechanical quality factor Qm=45, and the dielectric constant εr=720). As the increase of the polarization votage, the ceramic piezoelectric properties are increased. When the polarization voltage E=3kV/mm, the polarization tends to be saturation on the whole.

2014 ◽  
Vol 887-888 ◽  
pp. 289-293
Author(s):  
Jing Chang Zhao ◽  
Zhen Lai Zhou

(Na,Bi)TiO3-BaTiO3lead free piezoelectric ceramics were fabricated with modification of CaCu3Ti4O12additives. The phase structure, morphology, dielectric and piezoelectric properties of prepared samples were investigated, respectively. It was found that CaCu3Ti4O12additives evidently improve the polarization properties of (Na,Bi)TiO3-BaTiO3lead free ceramics and the obtained samples exhibit an excellent piezoelectric properties (electromechanical coupling factorKp=31%, mechanical quality factorQm=151 and piezoelectric constantd33=160pC/N). According to results, the effect of CaCu3Ti4O12additives on electrical properties of (Na,Bi)TiO3-BaTiO3lead free piezoelectric ceramics is discussed.


2011 ◽  
Vol 239-242 ◽  
pp. 3240-3243 ◽  
Author(s):  
Chun Huy Wang

Extending the investigations on (Bi0.5Na0.5)TiO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3[BNT-BKT]. (Bi0.5Na0.5)TiO3with 7~ 30 mol% (Bi0.5K0.5)TiO3ceramics have been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) was found at the composition 0.82BNT-0.18BKT with correspondingly enhanced piezoelectric properties. The electromechanical planar coupling factor is higher for compositions near the MPB. The mechanical quality factor (Qm), planar coupling coefficient (kp) and thickness coupling coefficient (kt) of 0.82BNT-0.18BKT ceramics were 125, 28.8% and 47.4%, respectively.


2012 ◽  
Vol 549 ◽  
pp. 651-654 ◽  
Author(s):  
Zhi Wen Zhu ◽  
Xin You Huang ◽  
Hai Tang Hua ◽  
Yan Li

Ba0.85Ca0.15Ti0.9Zr0.1O3-xLi2CO3 lead-free piezoelectric ceramics (abbreviated as BCZT-xLi) were prepared by conventional solid state reaction method. The microstructure, piezoelectric properties and dielectric properties were studied for BCZT-xLi samples doped with different Li2CO3 content(x= 0, 0.05, 0.1 0.2 0.3, 0.4wt. %). The results show that the piezoelectric constant(d33), planar electron mechanical coupling coefficient(kp) and thickness electron mechanical(kt) of BCZ-T-xLi ceramics increase firstly and decreases subsequently with increasing of Li+ doping amount, the dielectric loss(tanδ) of BCZT-xLi ceramics decreases firstly and then increases at the same time while Li+ doping amount increases. But the r-elative permittivity (εr) of BCZT-xLi ceramics increases all the time. With the in-creasing of the amount of Li2CO3 doped the grain size of BCZT-Li ceramic first increases and then decreases. The BCZT-xLi ceramics display the optimum properties (d33=83, tanδ=0.035, εr=2020, kp=0.41, kt=0.046) while Li2CO3 doped amount is 0.20wt. %.


Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 705
Author(s):  
Yunfeng Deng ◽  
Junjun Wang ◽  
Chunxiao Zhang ◽  
Hui Ma ◽  
Chungeng Bai ◽  
...  

Structural, ferroelectric, dielectric, and piezoelectric properties of K0.5Na0.5NbO3-LiTaO3-xmol%MnO2 lead-free piezoelectric ceramics with 0.0 ≤ x ≤ 0.3 were studied. The ceramic samples were synthesized through the conventional solid-state reaction method. The MnO2 addition can reduce the sintering temperature of KNLNT ceramics. Compared with undoped KNLNT ceramic, the piezoelectric measurements showed that piezoelectric properties of K0.5Na0.5NbO3-LiTaO3-xMnO2 were improved (d33 = 251 pC/N) when x = 0.1. In addition, KNLNT-xMnO2 ceramics have larger Pr(20.59~21.97 μC/cm2) and smaller Ec(10.77~6.95 kV/cm), which indicates MnO2 has excellent softening property, which improves the ferroelectric properties of KNLNT ceramics This work adds relevant information regarding of potassium sodium niobate K0.5Na0.5NbO3 (KNN) when doped Li, Ta, Mn at the B-site.


2010 ◽  
Vol 156-157 ◽  
pp. 1522-1527
Author(s):  
Bei Xu ◽  
Feng Gao ◽  
Bo Li ◽  
Liang Liang Liu ◽  
Zhen Qi Deng

Li+ and Ta5+ modified lead-free piezoelectric ceramics [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 have been prepared by an ordinary sintering technique. Effect of Li+ and Ta5+ on microstructure and piezoelectric properties of the ceramics was systematically studied. A morphotropic phase boundary between orthorhombic and tetragonal phases is identified in the composition range of (0.02≤x≤0.04, 0.15≤y≤0.25), which can enhance electrical properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 ceramics. The Curie temperature TC of these ceramics is lower than that of pure (K0.5Na0.5)NbO3 ceramics, but the temperature of orthorhombic to tetragonal phase transition TO-T of the former is higher than that of the latter. TC and TO-T both decrease as the content of Ta5+ increases. With the addition of Li+ increasing, TC increases. The optimal piezoelectric properties are obtained at (x, y)=(0.03, 0.20): piezoelectric constant d33 is 192pC/N; the electromechanical coefficient of the planar mode kp is 44%; room temperature dielectric constant εr is 1049, and the corresponding mechanical quality factor Qm is 49.


2007 ◽  
Vol 42 (9) ◽  
pp. 1594-1601 ◽  
Author(s):  
Hongliang Du ◽  
Fusheng Tang ◽  
Fa Luo ◽  
Dongmei Zhu ◽  
Shaobo Qu ◽  
...  

2007 ◽  
Vol 334-335 ◽  
pp. 957-960
Author(s):  
Hu Yong Tian ◽  
Wan Ping Chen ◽  
D.Y. Wang ◽  
Y. Wang ◽  
J.T. Zeng ◽  
...  

Lead-free piezoelectric ceramics based on bismuth sodium titanate (BNT) -barium hafnate titanate (BHT) were prepared by a two-step synthesis process. The final BNT-BHT ceramics sintered at 1180oC for 2 h in air showed a perovskite structure with high density. The morphotropic phase boundaries (MPB) were found in BNT based piezoelectric ceramics with 8~10 wt% BHT in composites. In the case of Bi0.5Na0.5TiO3-0.08BaHf0.05Ti0.95O3 ceramics, a maximum piezoelectric coefficient d33 of 122.6 pC/N was obtained. The remnant polarization (Pr) and coercive field (Ec) were measured and the relationship between ferroelectricity and the BHT fraction in the compounds was investigated. The BNT-BHT ceramics were expected to be a new and promising candidate for lead-free piezoelectric device applications.


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