scholarly journals Electrothermal Phenomena in Ferroelectrics

Actuators ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 93
Author(s):  
Kenji Uchino
Keyword(s):  
Thermal Diffusivity ◽  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Short Circuit ◽  
Electromechanical Coupling Factor ◽  
Lead Zirconate ◽  
Coupling Factor ◽  
Open Circuit ◽  
Comprehensive Knowledge ◽  
Poling Direction

Physical properties of lead-zirconate-titanate (PZT) ceramics change according to the initial electric poling process and electrical boundary conditions. This paper reports the electrothermal, piezothermal, and piezoelectric coupling phenomena in ferroelectrics from thermodynamics viewpoints, in particular, thermal property differences between unpoled and poled PZT’s in the poling direction for open circuit and short circuit conditions. We propose a new terminology, “secondary electrothermal” coupling factor kλ, which is analogous to the electromechanical coupling factor k, relating the elastic compliances under short- and open-circuit conditions, in order to explain the fact that the short-circuit condition exhibited the larger thermal diffusivity than the open-circuit condition. On the other hand, the unpoled specimen exhibits the lowest thermal diffusivity. This tutorial paper was authored for providing comprehensive knowledge on equilibrium and time-dependent thermodynamics in ferroelectrics.

Thermal Conductivities of PZT Piezoelectric Ceramics under Different Electrical Boundary Conditions

2020 ◽  
Vol 3 (1) ◽  
pp. 10
Author(s):  
Husain N.  Shekhan ◽  
Erkan A.  Gurdal ◽  
Lalitha Ganapatibhotla ◽  
Janna K.  Maranas ◽  
Ron Staut ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Boundary Conditions ◽  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Short Circuit ◽  
Coupling Factor ◽  
Open Circuit ◽  
Electrical Boundary Conditions ◽  
Poling Direction

<p>Physical properties of polycrystalline lead-zirconate-titanate (PZT) changes according to electrical boundary conditions and poling. This paper reports the thermal properties of poled and unpoled PZT's in the poling direction for open circuit and short circuit conditions. The authors found that the short-circuit condition exhibited the largest thermal conductivity than the open-circuit condition. In the relationship between these two thermal properties, the authors propose the "electrothermal" coupling factor k<sup>κ</sup><sub>33</sub>, which is similar to the electromechanical coupling factor k<sub>33</sub> relating the elastic compliances under short- and open-circuit conditions. On the other hand, the thermal conductivity of the unpoled specimen exhibits the lowest thermal conductivity, in comparison with the poled specimens, which suggests the importance of phonon mode scattering on the thermal conductivity with respect to elastic compliance.</p>

scholarly journals A New Electrical Circuit With Negative Capacitances to Enhance Resistive Shunt Damping

2015 ◽  
Author(s):  
Marta Berardengo ◽  
Stefano Manzoni ◽  
Olivier Thomas ◽  
Christophe Giraud-Audine
Keyword(s):  
Electromechanical Coupling ◽  
Short Circuit ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Open Circuit ◽  
Electrical Circuit ◽  
Structural Vibration ◽  
Electrical Network ◽  
Negative Capacitance ◽  
Shunt Damping

This article proposes a new layout of electrical network based on two negative capacitance circuits, aimed at increasing the performances of a traditional resistive piezoelectric shunt for structural vibration reduction. It is equivalent to artificially increase the modal electromechanical coupling factor of the electromechanical structure by both decreasing the short-circuit natural frequencies and increasing the open-circuit ones. This leads to higher values of the modal electromechanical coupling factor with respect to simple negative capacitance configurations, when the same margin from stability is considered. This technique is shown to be powerful in enhancing the control performance when associated to a simple resistive shunt, usually avoided because of its poor performances.

Piezoelectric Thin Film Ultrasonic Micromotors

1991 ◽  
Vol 243 ◽  
Author(s):  
K. R. Udayakumar ◽  
J. Chen ◽  
K. G. Brooks ◽  
L. E. Cross ◽  
A. M. Flynn ◽  
...  
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Breakdown Strength ◽  
Relative Dielectric Constant ◽  
Electromechanical Coupling Factor ◽  
Lead Zirconate ◽  
Coupling Factor ◽  
New Family ◽  
Piezoelectric Thin Film

AbstractThin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant and breakdown strength of the films lead to high stored energy densities. Evaluation of the film as a bimorph yielded a value of -88 pC/N for the transverse piezoelectric strain coefficient, d31; the relevant electromechanical coupling factor, k31, calculated thereupon was 0.22. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimized prototype micromotors show rotational velocities of 100-300 rpm at drives of 3-5 V.

Piezoelectric Behavior Based on Mixing-Doped in Lead Zirconate Titanate Ceramics and Application

2011 ◽  
Vol 189-193 ◽  
pp. 4126-4129
Author(s):  
Bing Huei Chen ◽  
Long Wu
Keyword(s):  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Piezoelectric Properties ◽  
Electromechanical Coupling Factor ◽  
Lead Zirconate ◽  
Coupling Factor ◽  
Mechanical Quality Factor ◽  
Ceramic Technology ◽  
Zirconate Titanate ◽  
Cation And Anion Vacancies

In this investigation, we extend our previous works to improve piezoelectric properties of Pb(Zr,Ti)O3 ceramics. Modified lead zirconate titanate (PZT) piezoceramics with a composition Zr/Ti=53/47 containing a trace of mixing dopants were prepared by conventional ceramic technology sintering powder compacts. Replacement of (Zr, Ti)+4 by Nb+5, Pb+2 by Sb+3 and Mn+4 in PZT perovskite type solid solutions was accomplished by the creation of cation and anion vacancies. Modified ceramics were explored as a function of firing temperature to acquire exceedingly good piezoelectric characterizations. From the analysis results, calcined at 850°C for 2 h, and then sintered at 1280°C for 2 h, PZT piezoceramic showed the larger dielectric constant er 2013, mechanical quality factor Qm 120 and maximum electromechanical coupling factor kp 0.67. Besides, the bulk ceramic grains distribution were found to be uniform. Furthermore, the sample was found to possess piezoelectric properties, the resonance frequency being about 200 KHz suitable for acoustic sensor.

Relaxor Single Crystals with Giant k31 Mode

2006 ◽  
Vol 45 ◽  
pp. 2412-2421
Author(s):  
Toshio Ogawa
Keyword(s):  
Single Crystal ◽  
Electromechanical Coupling ◽  
Impedance Measurement ◽  
Hysteresis Loops ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Poling Direction ◽  
Length Direction ◽  
Relaxor Single Crystals ◽  
The Relationship

Giant electromechanical coupling factor of k31 mode over 86% was found for (100) Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 and (110) Pb[(Mg1/3Nb2/3)0.74Ti0.26]O3 single-crystal plates poled in the [100] and [110] directions, respectively. The P-E hysteresis loops in the single-crystal plates with giant k31 became asymmetric. Furthermore, the frequency response of impedance in these plates with giant k31 consisted of a single vibration in the length direction. A mechanism to realize giant k31 can be explained by the relationship between the crystal plane and poling direction. In addition, the existence of giant piezoelectric d31 constant was proven by the strain measurement as well as by the impedance measurement.

scholarly journals Effect of Polymer-Ceramic Fibre Interphase Design on Coupling Factor in Low Fibre Volume Content Piezoelectric Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Tony Lusiola ◽  
Sophie Oberle ◽  
Lovro Gorjan ◽  
Frank Clemens
Keyword(s):  
Epoxy Resin ◽  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Electromechanical Coupling Factor ◽  
Polymer Coatings ◽  
Coupling Factor ◽  
Fibre Volume ◽  
Resin Matrix ◽  
Ceramic Fibre ◽  
Soft Polymer

In this work, we investigated different short molecule polymer coatings in piezoelectric ceramic-polymer composites with low fibre volume contents. Modifying the interphase between the piezoelectric PZT (lead zirconate titanate) fibre and the epoxy matrix thus enhances the electromechanical coupling factor for 1–3 ultrasound transducers with low fibre contents. It is known that the electromechanical coupling factor can be increased by precoating a ceramic fibre with a soft interlayer polymer [1-1-3]. In this paper, we investigate the so-called 1-1-1-3 composites composed of a ferroelectric ceramic fibre (core), a soft polymer layer (e.g., fatty acids, amides, waxes, or oils), an epoxy resin shell, and an epoxy resin matrix. Some soft polymer layers allowed the free movement of the ferroelectric fibres reducing blocking or clamping by the inactive polymeric matrix, resulting in higher electromechanical coupling factors (kt) for composites with low fibre volume contents. Using an oil-based interlayer, the dielectric constant can be significantly increased. The lowest fibre push-out stress could be achieved with the paraffin interlayer; however, no correlation with the coupling factor could be observed.

scholarly journals Energy Harvester Based on the Synchronization Phenomenon of a Circular Cylinder

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Junlei Wang ◽  
Jingyu Ran ◽  
Zhien Zhang
Keyword(s):  
Circular Cylinder ◽  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Lead Zirconate ◽  
Open Circuit ◽  
Fluid Field ◽  
Voltage Output ◽  
Lift And Drag ◽  
Lift And Drag Coefficient ◽  
High Level

A concept of generating power from a circular cylinder undergoing vortex-induced vibration (VIV) was investigated. Two lead zirconate titanate (PZT) beams which had high power density were installed on the cylinder. A theoretical model has been presented to describe the electromechanical coupling of the open-circuit voltage output and the vibration amplitudes based on a second-order nonlinear Van der pol equation and Gauss law. A numerical computation was applied to measure the capacity of the power generating system. The lift and drag coefficient and the vortex shedding frequency were obtained to verify how the nondimensional parameter reduced velocityUraffects the fluid field. Meanwhile, a single-degree of freedom system has been added to describe the VIV, presynchronization, and synchronization together with postsynchronization regimes of oscillating frequencies. And the amplitudes of the vibration have been obtained. Finally, the vibrational amplitudes and the voltage output could go up to a high level in the synchronization region. The maximum value of the voltage output and the corresponding reduced velocityUrwere 8.42 V and 5.6, respectively.

High Electromechanical Coupling Piezoelectrics - How High Energy Conversion Rate is Possible

1996 ◽  
Vol 459 ◽  
Author(s):  
Kenji Uchino
Keyword(s):  
Energy Conversion ◽  
Lead Zirconate Titanate ◽  
Conversion Rate ◽  
Electromechanical Coupling ◽  
Crystal Form ◽  
Lead Zirconate ◽  
High Energy ◽  
Coupling Factor ◽  
Lead Zinc ◽  
Titanate Ceramics

ABSTRACTA new category of piezoelectric ceramics with very high electromechanical coupling was discovered in a lead zinc niobate:lead titanate solid solution in a single crystal form. The maximum coupling factor k33 reaches 95%, which corresponds to the energy conversion rate twice as high as the conventional lead zirconate titanate ceramics. This paper reviews the previous studies on superior piezoelectricity in relaxor ferroelectric: lead titanate solid solutions and on the possible mechanisms of this high electromechanical coupling.

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