Negative-pressure enhanced ferroelectricity and piezoelectricity in lead-free BaTiO3 ferroelectric nanocomposite films

2020 ◽  
Vol 8 (24) ◽  
pp. 8091-8097 ◽  
Author(s):  
Xiyuan Zhang ◽  
Ruixing Xu ◽  
Xingyao Gao ◽  
Yanda Ji ◽  
Fengjiao Qian ◽  
...  
Keyword(s):  
High Temperature ◽  
Curie Temperature ◽  
Negative Pressure ◽  
Piezoelectric Coefficient ◽  
Lead Free ◽  
Nanocomposite Films

Negative pressure enhances the ferroelectric Curie temperature and piezoelectric coefficient in lead-free monoclinic BaTiO3 films for high-temperature ferroelectric applications.

Improved Curie Temperature of Li-Doped Lead-Free (K,Na)NbO3 Ceramics Analysis

2014 ◽  
Vol 1061-1062 ◽  
pp. 91-95
Author(s):  
Rui Zhu Zhang ◽  
Wen Peng Guo ◽  
Gao Lei Zhao
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Electromechanical Coupling ◽  
Piezoelectric Coefficient ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Lead Free ◽  
Tetragonal Symmetry ◽  
Negative Effects ◽  
Li Content

(K,Na)NbO3(KNN)-based lead-free piezoelectric ceramic could be fabricated by ordinary solid sintering method.This paper reported preferable properties of solid solutions (1-x)(Na0.535K0.480)NbO3-xLiNbO3(x=0.050,0.055,0.060,0.065 and 0.070 successively) all sintered at 1060°C.The nonconservation of charge suppressed negative effects caused by evaporations of K&Na and doped Li occupied A sites in ABO3perovskite structure lattices led to the intensification of lattice distortion.XRD result showd phase transition from coexistence of orthorhombic and tetragonal symmetry to tetragonal.Polymorphic phase boundary could be observed when 0.050≤ x≤ 0.060.Coexistence of orthorhombic and tetragonal phases brought improvements of piezoelectric coefficient d33and electromechanical coupling factor kp,whose top values were 162 pC/N and 28.1% in this paper. Positive correlation between the Curie temperature and Li content proved that a distorted crystal lattice needed more energy to accomplish its phase transition from tetragonal to cubic than a normal one.

scholarly journals Ultra-high piezoelectric coefficients and strain-sensitive curie temperature in hydrogen-bonded systems

2020 ◽  
Author(s):  
Yangyang Ren ◽  
Menghao Wu ◽  
Jun-Ming Liu
Keyword(s):  
Monte Carlo Simulation ◽  
Curie Temperature ◽  
First Principles ◽  
Tensile Strain ◽  
Room Temperature ◽  
Piezoelectric Coefficient ◽  
Lead Free ◽  
New Approach ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Abstract We propose a new approach to obtain ultra-high piezoelectric coefficients that can be infinitely large theoretically, where ferroelectrics with strain-sensitive Curie temperature are necessary. We show the first-principles plus Monte Carlo simulation evidence that many hydrogen-bonded ferroelectrics (e.g. organic PhMDA) can be ideal candidates, which are also flexible and lead-free. Owing to the specific features of hydrogen bonding, their proton hopping barrier will drastically increase with prolonged proton transfer distance, while their hydrogen-bonded network can be easily compressed or stretched due to softness of hydrogen bonds. Their barriers as well as the Curie temperature can be approximately doubled upon a tensile strain as low as 2%. Their Curie temperature can be tuned exactly to room-temperature by fixing a strain in one direction, and in another direction, an unprecedented ultra-high piezoelectric coefficient of 2058 pC/N can be obtained. This value is even underestimated and can be greatly enhanced when applying a smaller strain. Aside from sensors, they can also be utilized for converting either mechanical or thermal energies into electrical energies due to high pyroelectric coefficients.

Enhancing piezoelectric coefficient with high Curie temperature in BiAlO3-modified BiFeO3–BaTiO3 lead-free ceramics

2019 ◽  
Vol 98 ◽  
pp. 106040 ◽  
Author(s):  
Salman Ali Khan ◽  
Fazli Akram ◽  
Jihee Bae ◽  
Tauseef Ahmed ◽  
Tae Kwon Song ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Piezoelectric Coefficient ◽  
Lead Free ◽  
High Curie Temperature ◽  
Lead Free Ceramics

New Lead-Free Ferroelectric Materials for High-Temperature Applications: Nb-Doped Bi3.5Nd0.5Ti3 O12

2007 ◽  
Vol 280-283 ◽  
pp. 247-250
Author(s):  
Zi Ping Cao ◽  
Ai Li Ding ◽  
Xi Yun He ◽  
Y. Zhang ◽  
X. Zeng
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Curie Temperature ◽  
Ferroelectric Materials ◽  
Lead Free ◽  
High Curie Temperature ◽  
Pressing Method ◽  
Xrd Diffraction ◽  
Suitable Amount ◽  
Symmetry Change

Bi3.5Nd0.5Ti3O12 (BNT) ferroelectrics modified with different concentrations of Nb are prepared by a hot-pressing method. XRD diffraction shows that all samples have only a layeredstructured pervoskite phase. Raman spectra confirm that the crystal symmetry change locally when increasing Nb concentration. It is found that the introduction of a suitable amount of Nb can enhance the remnant polarization of BNT. The temperature dependence of dielectric constant is also investigated in BNT ceramics. All samples have high Curie temperature above 530°C.

Shear Strength and Dsc Analysis of High-Temperature Solders

2013 ◽  
Vol 58 (2) ◽  
pp. 529-533 ◽  
Author(s):  
R. Koleňák ◽  
M. Martinkovič ◽  
M. Koleňáková
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Lead Free ◽  
Dsc Analysis ◽  
Ultrasonic Activation ◽  
Metallic Substrates ◽  
Cu Substrate ◽  
Lead Free Solders

The work is devoted to the study of shear strength of soldered joints fabricated by use of high-temperature solders of types Bi-11Ag, Au-20Sn, Sn-5Sb, Zn-4Al, Pb-5Sn, and Pb-10Sn. The shear strength was determined on metallic substrates made of Cu, Ni, and Ag. The strength of joints fabricated by use of flux and that of joints fabricated by use of ultrasonic activation without flux was compared. The obtained results have shown that in case of soldering by use of ultrasound (UT), higher shear strength of soldered joints was achieved with most solders. The highest shear strength by use of UT was achieved with an Au-20Sn joint fabricated on copper, namely up to 195 MPa. The lowest average values were achieved with Pb-based solders (Pb-5Sn and Pb-10Sn). The shear strength values of these solders used on Cu substrate varied from 24 to 27 MPa. DSC analysis was performed to determine the melting interval of lead-free solders.

Enhanced piezoelectric coefficient of HfO2-modified (K0.44Na0.56)0.94Li0.06(Nb0.94Sb0.06)O3 lead-free ceramics

2014 ◽  
Vol 40 (2) ◽  
pp. 3755-3759 ◽  
Author(s):  
Tao Chen ◽  
Hongli Wang ◽  
Ting Zhang ◽  
Guangchang Wang ◽  
Jifang Zhou ◽  
...  
Keyword(s):  
Piezoelectric Coefficient ◽  
Lead Free ◽  
Lead Free Ceramics
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