scholarly journals Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations

2016 ◽  
Vol 2 (9) ◽  
pp. e1501814 ◽  
Author(s):  
Michael E. Manley ◽  
Douglas L. Abernathy ◽  
Raffi Sahul ◽  
Daniel E. Parshall ◽  
Jeffrey W. Lynn ◽  
...  
Keyword(s):  
Local Structure ◽  
Electromechanical Coupling ◽  
Collective Motion ◽  
Piezoelectric Materials ◽  
Relaxor Ferroelectrics ◽  
Piezoelectric Response ◽  
Atomic Displacements ◽  
Electromechanical Responses ◽  
Polar Nanoregions ◽  
Ultrasound Applications

Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 − x)[Pb(Mg1/3Nb2/3)O3] – xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening.

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 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 Comment on “Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations”

2019 ◽  
Vol 5 (3) ◽  
pp. eaar5066 ◽  
Author(s):  
P. M. Gehring ◽  
Zhijun Xu ◽  
C. Stock ◽  
Guangyong Xu ◽  
D. Parshall ◽  
...  
Keyword(s):  
Acoustic Phonon ◽  
Electromechanical Coupling ◽  
Relaxor Ferroelectrics ◽  
Alternative Interpretation ◽  
Relaxor Ferroelectric ◽  
Lattice Vibrations ◽  
Phonon Branch ◽  
Transverse Acoustic ◽  
Neutron Wavelength ◽  
Polar Nanoregions

Manley et al. (Science Advances, 16 September 2016, p. e1501814) report the splitting of a transverse acoustic phonon branch below TC in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)1−xTix]O3 with x = 0.30 using neutron scattering methods. Manley et al. argue that this splitting occurs because these phonons hybridize with local, harmonic lattice vibrations associated with polar nanoregions. We show that splitting is absent when the measurement is made using a different neutron wavelength, and we suggest an alternative interpretation.

Sol-Gel Derived PZT Thick Films with Nano-Sized Microstructure

2002 ◽  
Vol 748 ◽  
Author(s):  
C. L. Zhao ◽  
Z. H. Wang ◽  
W. Zhu ◽  
O. K. Tan ◽  
H. H. Hng
Keyword(s):  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Thick Films ◽  
Sol Gel ◽  
Essential Element ◽  
Processing Parameters ◽  
Lead Zirconate ◽  
Piezoelectric Response ◽  
Coupling Coefficients ◽  
Pzt Films

ABSTRACTLead zirconate titanate (PZT) films are promising for acoustic micro-devices applications because of their extremely high electromechanical coupling coefficients and excellent piezoelectric response. Thicker PZT films are crucial for these acoustic applications. A hybrid sol-gel technology has been developed as a new approach to realize simple and cost-effective fabrication of high quality PZT thick films. In this paper, PZT53/47 thick films with a thickness of 5–50 μm are successfully deposited on Pt-coated silicon wafer by using the hybrid sol-gel technology. The obtained PZT thick films are dense, crack-free, and have a nano-sized microstructure. The processing parameters of this technology have been evaluated. The microstructure of the film has been observed using field-emission scanning electron microscopy and the crystallization process has been monitored by the X-ray diffraction. The thick films thus made are good candidates for fabrication of piezoelectric diaphragm which will be an essential element of microspeaker and microphone arrays.

scholarly journals Piezoelectric polar nanoregions and relaxation-coupled resonances in relaxor ferroelectrics

2018 ◽  
Vol 98 (13) ◽  
Author(s):  
Ling Cai ◽  
Radha Pattnaik ◽  
Joel Lundeen ◽  
Jean Toulouse
Keyword(s):  
Relaxor Ferroelectrics ◽  
Polar Nanoregions

scholarly journals FEM Analysis of Various Multilayer Structures for CMOS Compatible Wearable Acousto-Optic Devices

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7863
Author(s):  
Mehwish Hanif ◽  
Varun Jeoti ◽  
Mohamad Radzi Ahmad ◽  
Muhammad Zubair Aslam ◽  
Saima Qureshi ◽  
...  
Keyword(s):  
Coupling Coefficient ◽  
Figure Of Merit ◽  
Electromechanical Coupling ◽  
Piezoelectric Materials ◽  
Fem Analysis ◽  
Film Structure ◽  
Multilayer Structures ◽  
Electromechanical Coupling Coefficient ◽  
Materials Used ◽  
The Individual

Lately, wearable applications featuring photonic on-chip sensors are on the rise. Among many ways of controlling and/or modulating, the acousto-optic technique is seen to be a popular technique. This paper undertakes the study of different multilayer structures that can be fabricated for realizing an acousto-optic device, the objective being to obtain a high acousto-optic figure of merit (AOFM). By varying the thicknesses of the layers of these materials, several properties are discussed. The study shows that the multilayer thin film structure-based devices can give a high value of electromechanical coupling coefficient (k2) and a high AOFM as compared to the bulk piezoelectric/optical materials. The study is conducted to find the optimal normalised thickness of the multilayer structures with a material possessing the best optical and piezoelectric properties for fabricating acousto-optic devices. Based on simulations and studies of SAW propagation characteristics such as the electromechanical coupling coefficient (k2) and phase velocity (v), the acousto-optic figure of merit is calculated. The maximum value of the acousto-optic figure of merit achieved is higher than the AOFM of all the individual materials used in these layer structures. The suggested SAW device has potential application in wearable and small footprint acousto-optic devices and gives better results than those made with bulk piezoelectric materials.

Electromechanical Coupling of PZT Nanofibers

2008 ◽  
Author(s):  
Shiyou Xu ◽  
Yong Shi
Keyword(s):  
Forced Vibration ◽  
Output Voltage ◽  
Electromechanical Coupling ◽  
Mechanical Strain ◽  
Electrospinning Process ◽  
Piezoelectric Response ◽  
Vibration Source ◽  
Titanium Film ◽  
Three Point Bending ◽  
Vibration Tests

This paper presented the results of electromechanical characterization of PZT nanofibers through applied mechanical strain and forced vibration. PZT nanofibers were fabricated by electrospinning process. Titanium film with ZrO2 layer was used to collect the nanofibers and also used as the substrates of the test coupons for the bending tests. Mechanical strain was applied to the test coupons through three-point-bending using Dynamic Mechanical Analyzer (DMA). The largest output voltage was 170mV under 0.5% applied strain. Silicon substrate with trenches was also used to collect the PZT nanofibers for the forced vibration tests. The output voltage from 150Hz sinusoid vibration source was also measured. The peaks of the output voltage were 64.9mV and −95.9mV, respectively. These tests have demonstrated the piezoelectric response of PZT nanofibers. Further tests are to be conducted to precisely determine the piezoelectric constants of PZT nanofibers.

Application of Piezoelectric Materials for Monitoring the Growth of Defects in Structures

2010 ◽  
Vol 643 ◽  
pp. 113-118 ◽  
Author(s):  
Sergio Ricardo Kokay Morikawa ◽  
Daniel Pontes Lannes ◽  
Antonio Lopes Gama
Keyword(s):  
Strain Field ◽  
Piezoelectric Materials ◽  
Piezoelectric Actuators ◽  
Frame Structure ◽  
Piezoelectric Sensors ◽  
Dynamic Strain ◽  
Damage Growth ◽  
Defect Depth ◽  
Active Method ◽  
Electromechanical Responses

This paper presents the results of an experimental investigation on the use of piezoelectric materials as a technique for monitoring the growth of defects in structures. The method consists of exciting the structure with piezoelectric actuators while recording the electromechanical responses from sensors placed close to the defect. The piezoelectric sensors detect the damage growth or an incipient defect by monitoring changes in the dynamic strain field, induced by the piezoelectric actuator, near the defect. This technique was evaluated through experiments using an aluminum frame structure. Results show that the piezoelectric active method is capable of detecting small changes in defect depth.

Optimisation of a Hybrid Energy Scavenger with Piezoelectric/Magnetic Coupling for Sensor-Bearing Units

2013 ◽  
Vol 745 ◽  
pp. 41-56 ◽  
Author(s):  
Eugenio Brusa
Keyword(s):  
Energy Conversion ◽  
Rolling Mill ◽  
Structural Damage ◽  
Electromechanical Coupling ◽  
Permanent Magnets ◽  
Piezoelectric Materials ◽  
Vibration Monitoring ◽  
Vibration Energy Harvesting ◽  
Distributed Sensors ◽  
Energy Scavenger

Vibration monitoring based on wireless distributed sensors is currently used in steelmaking plants to early detect structural damage occurring in the rolling mill components. This approach allows overcoming some severe limitations of access to those industrial equipments, but sensors need a local power supply. Vibration energy harvesting based on piezoelectric materials is therefore proposed for this purpose. Nevertheless, very often it happens that dimensions of the energy scavenger are incompatible with the size of the system, thus not allowing a perfect tuning of its resonance upon the frequency of the dynamic excitation. Moreover, sometimes the amplitude of vibration is too low to induce a sufficient amount of energy conversion. Those problems motivated a previous work of the author, about the feasibility of plucking the flexible structure through either a relative motion or rotation of the harvested system and the energy scavenger, respectively. To avoid the drawbacks due to the wear in plucking the material, a contactless electromechanical coupling was proposed. The interaction between two permanent magnets, being one applied to the scavenger tip and the other fixed, was used to excite the vibration and the electromechanical conversion through the piezoelectric layer. The effectiveness of such hybrid system composed by the structure with surface bonded piezoelectric layers and the couple of magnets was investigated and compared to the power requirements of some sensors currently used to measure the dynamic response of the backup roll bearings located at the outer crown of the rolling mill. An optimisation of the whole device to increase the overall performance is proposed by following some approaches assessed in the literature and tested on some specimens of energy scavenger. The optimisation activity was based on a suitable selection of the piezoelectric material aimed at reaching the highest electromechanical coupling with a good mechanical strength and on a suitable shaping of the electrode surface aimed at assuring the largest efficiency in the energy conversion.

Fabrication Methods for Improved Electromechanical Behavior in Piezoelectric Membranes

2005 ◽  
Vol 872 ◽  
Author(s):  
M.C. Robinson ◽  
P.D. Hayenga ◽  
J.H. Cho ◽  
C.D. Richards ◽  
R.F. Richards ◽  
...  
Keyword(s):  
Residual Stress ◽  
Electromechanical Coupling ◽  
Silicon Oxide ◽  
Piezoelectric Materials ◽  
Electrical Energy ◽  
Fabrication Technique ◽  
Simply Supported ◽  
Electromechanical Behavior ◽  
Pzt Films ◽  
Electrode Coverage

AbstractPiezoelectric materials convert mechanical to electrical energy under stretching and bending conditions. Optimizing the coupling conversion is imperative to the electromechanical behavior of a micromachined membrane's performance. This paper discusses analytical calculations that were devised to determine the microscale structure that minimizes residual stress and outlines the implementation of fabrication technique variations including three different electrode configurations, trenching around the membrane, and reducing the total composite residual stress of the support structure using compressive silicon oxide. Lead zirconacte titanate (PZT) films between 1 and 3 μm thick with a ratio of Zr to Ti of 40:60 were deposited onto 3 mm square silicon membranes. The total tensile stress in the composite structure reaches 100 MPa during standard fabrication processing. Utilizing analytical calculations, a structure was determined that lowered the residual stress of the composite to 11 MPa and increased the electromechanical coupling 35 times. Changing the geometry of the electrode coverage decreased the residual stress of the composite by 40%. Trenching around the membrane provided a membrane with boundary conditions that approached simply supported and decreased the composite residual stress by another 16%. A comparison of the electromechanical behavior for these structures will be discussed, showing a route towards increasing electromechanical coupling in PZT MEMS.

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