FLEXOELECTRIC COMPOSITE — A NEW PROSPECT FOR LEAD-FREE PIEZOELECTRICS

2010 ◽  
Vol 03 (01) ◽  
pp. 79-81 ◽  
Author(s):  
BAOJIN CHU ◽  
WENYI ZHU ◽  
NAN LI ◽  
L. ERIC CROSS
Keyword(s):  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Physical Phenomenon ◽  
Mechanical Strain ◽  
Dielectric Materials ◽  
Electric Polarization ◽  
Lead Free ◽  
Piezoelectric Response ◽  
Bst Ceramics ◽  
Better Than

Flexoelectricity describes the physical phenomenon of the generation of electric polarization from mechanical strain gradient in solid insulators. In common dielectric materials, the flexoelectric coefficient is trivially small ~10-10 C/m. In Ba(Sr,Ti)O 3 (BST) ceramics, flexoelectric coefficient up to 10-4 C/m was observed. Such high coefficient makes it possible to design high piezoelectric response flexoelectric composites. In this letter, we will demonstrate that the newly designed flexoelectric composites could have piezoelectric properties better than conventional piezoelectric materials.

Phase diagram determination of large piezoelectric response in BHT-BCT ceramics

2019 ◽  
Vol 12 (05) ◽  
pp. 1950070 ◽  
Author(s):  
Zhonghua Dai ◽  
Dingyan Li ◽  
Jinglong Xie ◽  
Weiguo Liu ◽  
Shaobo Ge ◽  
...  
Keyword(s):  
Phase Diagram ◽  
High Performance ◽  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Electronic Devices ◽  
Lead Free ◽  
Piezoelectric Response ◽  
Cubic Phases ◽  
Co Doped

High-performance lead-free piezoelectric materials are environmentally friendly and in great demand for electronic devices. In this study, the phase diagram and properties of Hf, Ca co-doped BaTiO3 (BHT-BCT) were investigated. A triple-point morphotropic phase boundary separating the rhombohedral, tetragonal and cubic phases for the (1-[Formula: see text])Ba(Ti0.85Hf0.15)O3-[Formula: see text](Ba0.7Ca0.3)TiO3 system exited at [Formula: see text] High piezoelectric properties with piezoelectric coefficients [Formula: see text] (572pC/N) and Curie temperature [Formula: see text] (90∘C) of 0.55Ba(Ti0.85Hf0.15)O3-0.45(Ba0.7Ca0.3)TiO3 are achieved in the BaTiO3-based ceramics.

Enhanced Piezoelectric Properties of Lead-Free Piezoelectric Materials by Microstructure Control

2010 ◽  
Vol 402 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Satoshi Wada ◽  
Shigehito Shimizu ◽  
Petr Pulpan ◽  
Nobuhiro Kumada ◽  
Daisuke Tanaka ◽  
...  
Keyword(s):  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Lead Free ◽  
Microstructure Control

scholarly journals Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta co-doped w-AlN

2020 ◽  
Author(s):  
Mohammad Noor-A-Alam ◽  
Oskar Olszewski ◽  
Humberto Campanella ◽  
Michael Nolan
Keyword(s):  
Acoustic Wave ◽  
Density Functional ◽  
Electromechanical Coupling ◽  
Piezoelectric Materials ◽  
Electric Polarization ◽  
Piezoelectric Response ◽  
Co Doping ◽  
Piezoelectric Strain ◽  
Co Doped ◽  
Piezoelectric Strain Constant

<div>Based on density functional theory, we show that Li and</div><div>X (X=V, Nb and Ta) co-doping in 1Li:1X ratio broadens the</div><div>compositional freedom for significant piezoelectric enhancement in w-AlN, promising them to be good alternatives of expensive Sc. Interestingly, these co-doped w-AlN also show quite large spontaneous electric polarization about 0.80 C/m2 with the possibility of ferroelectric polarization switching, opening new possibilities in wurtzite nitrides. Increase in piezoelectric stress constant (e33) with decrease in elastic constant ( C33 ) results enhancement in piezoelectric strain constant ( d33 ), which is desired for improving the performance of resonators for high frequency RF signals. Also, these co-doped w-AlN are potential lead-free piezoelectric materials for energy harvesting and sensors as they improve the longitudinal electromechanical coupling constant (K^2 33), transverse piezoelectric strain constant (d31), and figure of merit for power generation. However, the enhancement in K^2 33 is not as pronounced as that in d33, because co-doping increases the dielectric constant. The longitudinal acoustic wave velocity (7.09 km/s) of Li0.1875Ta0.1875Al0.625N is quite comparable with that of commercially used piezoelectric LiNbO3 or LiTaO3 in special cuts (about 5~7 km/s) despite the fact that the acoustic wave velocities drop with co-doping or Sc concentration.</div>

Lead Free (Bi, Na)TiO3–BiAlO3 Ceramics for Piezoelectric Application

2020 ◽  
Vol 15 (4) ◽  
pp. 459-462
Author(s):  
Jae-Hoon Ji ◽  
Don-Jin Shin ◽  
Sang-Kwon Lee ◽  
Sang-Mo Koo ◽  
Jae-Geun Ha ◽  
...  
Keyword(s):  
Electromechanical Coupling ◽  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Lead Free ◽  
Electromechanical Coupling Coefficient ◽  
Substitution Effects ◽  
Sensors And Actuators ◽  
Device Applications ◽  
Piezoelectric Devices ◽  
Piezoelectric Charge

In this research, substitution effects of BiAlO3 with (Bi, Na)TiO3 piezoelectric ceramics was investigated for the sensors and actuators applications. (Bi,Na)TiO3 material has been employed for the piezoelectric devices applications because of their high piezoelectric charge constant, d33, of 88 pC/N, electromechanical coupling coefficient, kp, of 22% and inverse piezoelectric charge constant of 498 pm/V. As a piezoelectric material, (Bi, Na)TiO3 has perovskite structure with tetragonal basis. The improvement of piezoelectric and inverse piezoelectric properties is important for industrial device applications. Therefore, in this research, we have tried to increase functional and electrical properties of (Bi, Na)TiO3 piezoelectric materials by substituting BiAlO3 dopants. As a result, the piezoelectric constant was increased up to 140 pC/N, and the densification was increased up to 5.92 g/cm3 .

Piezoelectric Properties and Dielectric Property of Li Added KNN Ceramics

2013 ◽  
Vol 566 ◽  
pp. 72-75 ◽  
Author(s):  
Akihiro Mitani ◽  
Yoshinari Oba
Keyword(s):  
Dielectric Property ◽  
Curie Temperature ◽  
Perovskite Structure ◽  
High Performance ◽  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Environmental Issues ◽  
Lead Free ◽  
High Curie Temperature ◽  
A Site

Recently, high performance lead-free piezoelectric materials are strongly demanded for environmental issues. (K0.5Na0.5)NbO3 (KNN) has been attracting interest as lead-free piezoelectric ceramics because of its high Curie temperature and excellent piezoelectric properties. In this study, we investigated effects of Li addition on piezoelectric properties of (Li,Na,K)(Nb+Ta)O3+CuO,BaTiO3 . We found that optimum Li ratio of A site and B site on the perovskite structure increases relative density and .

scholarly journals Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta co-doped w-AlN

2020 ◽  
Author(s):  
Mohammad Noor-A-Alam ◽  
Oskar Olszewski ◽  
Humberto Campanella ◽  
Michael Nolan
Keyword(s):  
Acoustic Wave ◽  
Density Functional ◽  
Electromechanical Coupling ◽  
Piezoelectric Materials ◽  
Electric Polarization ◽  
Piezoelectric Response ◽  
Co Doping ◽  
Piezoelectric Strain ◽  
Co Doped ◽  
Piezoelectric Strain Constant

<div>Based on density functional theory, we show that Li and</div><div>X (X=V, Nb and Ta) co-doping in 1Li:1X ratio broadens the</div><div>compositional freedom for significant piezoelectric enhancement in w-AlN, promising them to be good alternatives of expensive Sc. Interestingly, these co-doped w-AlN also show quite large spontaneous electric polarization about 0.80 C/m2 with the possibility of ferroelectric polarization switching, opening new possibilities in wurtzite nitrides. Increase in piezoelectric stress constant (e33) with decrease in elastic constant ( C33 ) results enhancement in piezoelectric strain constant ( d33 ), which is desired for improving the performance of resonators for high frequency RF signals. Also, these co-doped w-AlN are potential lead-free piezoelectric materials for energy harvesting and sensors as they improve the longitudinal electromechanical coupling constant (K^2 33), transverse piezoelectric strain constant (d31), and figure of merit for power generation. However, the enhancement in K^2 33 is not as pronounced as that in d33, because co-doping increases the dielectric constant. The longitudinal acoustic wave velocity (7.09 km/s) of Li0.1875Ta0.1875Al0.625N is quite comparable with that of commercially used piezoelectric LiNbO3 or LiTaO3 in special cuts (about 5~7 km/s) despite the fact that the acoustic wave velocities drop with co-doping or Sc concentration.</div>

scholarly journals Local Piezoelectric Properties of Doped Biomolecular Crystals

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4922
Author(s):  
Andrei Kholkin ◽  
Denis Alikin ◽  
Vladimir Shur ◽  
Shiri Dishon ◽  
David Ehre ◽  
...  
Keyword(s):  
Guest Molecule ◽  
Piezoelectric Properties ◽  
Dipole Moments ◽  
Mechanical Strain ◽  
Piezoresponse Force Microscopy ◽  
Piezoelectric Response ◽  
Force Microscopy ◽  
Highly Sensitive ◽  
Molecule Interactions ◽  
Co Doped

Piezoelectricity is the ability of certain crystals to generate mechanical strain proportional to an external electric field. Though many biomolecular crystals contain polar molecules, they are frequently centrosymmetric, signifying that the dipole moments of constituent molecules cancel each other. However, piezoelectricity can be induced by stereospecific doping leading to symmetry reduction. Here, we applied piezoresponse force microscopy (PFM), highly sensitive to local piezoelectricity, to characterize (01¯0) faces of a popular biomolecular material, α-glycine, doped with other amino acids such as L-alanine and L-threonine as well as co-doped with both. We show that, while apparent vertical piezoresponse is prone to parasitic electrostatic effects, shear piezoelectric activity is strongly affected by doping. Undoped α-glycine shows no shear piezoelectric response at all. The shear response of the L-alanine doped crystals is much larger than those of the L-threonine doped crystals and co-doped crystals. These observations are rationalized in terms of host–guest molecule interactions.

Effect of Bi2O3 Addition on the Microstructure and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3-Ba(Sn0.02Ti0.98)O3 Ceramics

2013 ◽  
Vol 284-287 ◽  
pp. 3-7
Author(s):  
Chun Huy Wang
Keyword(s):  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Piezoelectric Properties ◽  
Piezoelectric Materials ◽  
Dominant Role ◽  
Lead Free ◽  
Coupling Coefficients ◽  
Sintering Process ◽  
Environment Problem ◽  
Lead Free Ceramics

PbZrO3-PbTiO3 (PZT)-based ceramics are playing a dominant role in piezoelectric materials, their evaporation of harmful lead oxide during the sintering process causes a crucial environment problem. It is necessary to search for lead-free piezoelectric materials that have such excellent properties as those found in the PZT-based ceramics. Therefore (Na0.5K0.5)NbO3-based solid solutions were studied to improve piezoelectric properties. In the present study, various quantities of Bi2O3 were added into 0.98(Na0.5K0.5)NbO3-0.02Ba(Sn0.02Ti0.98)O3 (0.98NKN-0.02BST) ceramics. It was found that 0.98NKN-0.02BST with the addition of 0~4.0 wt.% Bi2O3 exhibit relatively good piezoelectric properties. For 0.98NKN-0.02BST ceramic with the addition of 1.0 wt.% Bi2O3, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.21 and 0.46, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 2.2. It is obvious that 0.98NKN-0.02BST solid solution ceramic by adding low quantities of Bi2O3 is one of the promising lead-free ceramics for high frequency electromechanical transducer applications.

Effect of Additive Glycerol on Piezoelectric Properties of Modified Sol-Gel (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 Ceramics

2020 ◽  
Vol 993 ◽  
pp. 791-798
Author(s):  
Haibibu Aziguli ◽  
Tao Zhang ◽  
Ping Yu
Keyword(s):  
Grain Size ◽  
Electromechanical Coupling ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Environmental Concern ◽  
Sol Gel ◽  
Lead Free ◽  
Piezoelectric Response ◽  
Electromechanical Coupling Coefficient ◽  
Ceramic Powders

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) ceramics, one of the lead-free pizoelectric materials, were focused due to the environmental concern against lead. A modified BCTZ powder sol-gel fabrication process was experimentally introduced with the addition of glycerol, in order to provide an effective approach to optimize the piezoelectric response of BCTZ ceramics. The results showed that the piezoelectric properties enhanced in terms of the piezoelectric coefficient of d33, 510 pC/N and the electromechanical coupling coefficient of kp, 0.501. The enhancement in electrical properties, such as dielectric, ferroelectric and piezoelectric, could be related to the homogenous microstructure and larger grain size of BCTZ ceramic powders after the introduction of glycerol during the modified sol-gel strategy.

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