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Piezoelectric Ceramics: From Fundamentals to Applications

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced and Functional Ceramics and Glasses".

Deadline for manuscript submissions: closed (30 June 2021) | Viewed by 35942

Special Issue Editors

Instituto de Ciencia de Materiales de Madrid, CSIC. c/ Sor Juana Inés de la Cruz, 3. 24049 Madrid, Spain
Interests: piezoceramics; ferroelectrics; processing; characterization
Special Issues, Collections and Topics in MDPI journals
Department of Chemistry and Pharmacy University of Sassari. Via Vienna 2, I-07100 Sassari, Italy
Interests: piezoceramics; structural characterization; wet chemistry; processing
Special Issues, Collections and Topics in MDPI journals
Dpto. de Electrónica Física, Ingeniería Eléctrica y Física Aplicada, CEMDATIC-POEMMA, R&D Group, ETSIST, UPM, c/ Nikola Tesla, s/n, 28031 Madrid, Spain
Interests: piezoceramics; ferroelectrics; multiferroics; characterization

Special Issue Information

Dear Colleagues,

The poled polycrystalline ferroelectric materials, also known as piezoelectric ceramics, are the best example of multifunctionality. They have been classically used as sensors and actuators in all areas of daily life (telecommunications, industry, health, transport, etc.) and from the exploration of the universe to the exploration of the nanoworld. Indeed, telescopes use deformable mirrors containing hundreds of actuators. Further, piezoelectric scanners are a fundamental piece in all kinds of probe microscopes with a nanometer resolution. In addition, these versatile materials have in recent years found new uses in the field of the clean and renewable energy production systems, e.g., as mechanical harvesters. The limits of the use of piezoceramics are the limits of human ingenuity.

Piezoelectric ceramics, as they connect electrical and mechanical magnitudes, are complex to design for devices. Good electromechanical properties are a good starting point for applications. However, they must comply with strict mechanical properties’ requirements for long endurance in use. For this purpose, compulsorily, their processing has continuously been revised, and new cost-effective routes ensuring repeatability of the material production are tested. Commercial devices use lead titanate zirconate ceramics, which are prepared from lead oxide, a highly toxic compound, which must be replaced in devices according to the most recent regulations in force, e.g., in the European Community. For this reason, the investigation of ecological materials, without lead (lead-free), has experienced great growth in recent years, and examples of commercial applications are currently available.

Contributing manuscripts and review papers on the topics of new lead-free compositions and processing routes for bulk ceramics, thin and thick films and composites, on the structural, mechanical, coupled phenomena, ferroelectric and dielectric characterization, on modeling, and on application-oriented studies of these materials are welcomed. The editors are members of the European Institute of Piezoelectric Materials and Devices that is the co-organizer of the Conference “PIEZO2021: Piezoelectrics for End Users XI”, 21–24 February 2021, University of Sassary, Italy. Attendees to PIEZO2021 will enjoy a 10% discount of the APC for publishing the work presented at the Conference.

Prof. Lorena Pardo
Prof. Sebastiano Garroni
Prof. Amador M. González
Guest Editors

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Keywords

  • piezoceramics
  • ferroelectrics
  • processing
  • characterization
  • modeling
  • structure
  • lead-free
  • applications in acoustic
  • applications as ultrasound generators
  • sensors
  • actuators
  • piezoelectric energy harvesting and energy storage

Related Special Issue

Published Papers (11 papers)

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Research

Jump to: Review

10 pages, 17102 KiB  
Article
Structural Insights of Electrical Aging in PZT Thin Films as Revealed by In Situ Biasing X-ray Diffraction
Materials 2021, 14(16), 4500; https://doi.org/10.3390/ma14164500 - 11 Aug 2021
Cited by 3 | Viewed by 2145
Abstract
Electrical aging in lead zirconate titanate (PbZrxTi1−xO3) thin films has been intensively studied from a macroscopic perspective. However, structural origins and consequences of such degradation are less documented. In this study, we have used synchrotron radiation to [...] Read more.
Electrical aging in lead zirconate titanate (PbZrxTi1−xO3) thin films has been intensively studied from a macroscopic perspective. However, structural origins and consequences of such degradation are less documented. In this study, we have used synchrotron radiation to evaluate the behavior of ferroelectric domains by X-ray diffraction (XRD). The sample was loaded with an AC triangular bias waveform between ±10 V with a number of cycle varying from one up to 108. At each step of the aging procedure, XRD spectra had been collected in situ during the application of an electric field on a capacitor. The fine analysis of the (200) pseudo-cubic peak structure allows to separate the evolution of the volume of a/c tetragonal and rhombohedral domains along the electrical biasing. Throughout the aging, both intrinsic and extrinsic responses of tetra and rhombohedral domains are altered, the behavior depending on the observed phase. This methodology opens up new perspectives in the comprehension of the aging effect in ferroelectric thin film. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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13 pages, 3809 KiB  
Article
Processing Optimization and Toxicological Evaluation of “Lead-Free” Piezoceramics: A KNN-Based Case Study
Materials 2021, 14(15), 4337; https://doi.org/10.3390/ma14154337 - 03 Aug 2021
Cited by 7 | Viewed by 2083
Abstract
Due to the ever-increasing limitations of the use of lead-based materials, the manufacturing of lead-free piezoceramics with competitive piezoelectric properties and established nontoxicity is considered a priority for the scientific and industrial community. In this work, a lead-free system based on sodium potassium [...] Read more.
Due to the ever-increasing limitations of the use of lead-based materials, the manufacturing of lead-free piezoceramics with competitive piezoelectric properties and established nontoxicity is considered a priority for the scientific and industrial community. In this work, a lead-free system based on sodium potassium niobate (KNN), opportunely modified with MgNb2O6 (MN), was prepared through a combination of a mechanochemical activation method and air sintering, and its toxicity was evaluated. The effect of the mechanical processing on the microstructure refinement of the processed powders was established by X-ray diffraction and the average crystallite size content of the Nb2O5 species was evaluated. The experimental evidence was rationalized using a phenomenological model which permitted us to obtain the amount of powder processed at each collision and to optimize the activation step of the pre-calcined reagents. This influenced the final density and piezoresponse of the as-sintered pellets, which showed optimal properties compared with other KNN systems. Their toxicological potential was evaluated through exposure experiments to the pulverized KNN-based pellets, employing two widely used human and environmental cellular models. The in vitro assays proved, under the selected conditions, the absence of cytotoxicity of KNN-bases systems here studied. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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13 pages, 3497 KiB  
Article
Cyclic Mechanical Fatigue Lifetime of Bi0.5Na0.5TiO3-Based Eco-Piezoceramics
Materials 2021, 14(15), 4113; https://doi.org/10.3390/ma14154113 - 23 Jul 2021
Viewed by 1917
Abstract
The mechanical strength and cyclic fatigue behavior of PIC700 commercial eco-piezoceramic disks are investigated under biaxial loading on unpoled and poled samples. The bending strength of unpoled samples was higher than those of poled ones. Fatigue tests were conducted under a load ratio [...] Read more.
The mechanical strength and cyclic fatigue behavior of PIC700 commercial eco-piezoceramic disks are investigated under biaxial loading on unpoled and poled samples. The bending strength of unpoled samples was higher than those of poled ones. Fatigue tests were conducted under a load ratio of 10 at a frequency of 20 Hz with a sinusoidal waveform. The curve fitting for the S-N fatigue diagram is used to predict the lifetime of these eco-piezoceramics and describe their fatigue behavior. It was also found that the unpoled samples exhibited higher fatigue resistance than the poled ones. The fatigue limit of maximum load for ten million cycles of unpoled and poled samples was estimated to be 160 and 135 MPa, respectively. The detailed observations of the fatigue fracture surfaces by scanning electron microscopy (SEM) indicated that a wavy surface with a mixture of transgranular and intergranular fractures occurred preferentially in the case of the poled material. On the other hand, transgranular fractures seem to be predominant in the unpoled samples. It appears that the poling process causes the change in failure characteristics due to domain orientation that leaves an anisotropic stress field in the material. The poled ceramics possess a local stress concentration created by the orientation under the electric poling field of the 90° ferroelectric–ferroelastic domains. Under this local stress concentration, a microstructural degeneration is induced by domain switching under the cyclic load that accelerates crack growth, thereby reducing fatigue lifetime. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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15 pages, 2093 KiB  
Article
Determination of the PIC700 Ceramic’s Complex Piezo-Dielectric and Elastic Matrices from Manageable Aspect Ratio Resonators
Materials 2021, 14(15), 4076; https://doi.org/10.3390/ma14154076 - 22 Jul 2021
Cited by 6 | Viewed by 5936
Abstract
Achieving good piezoelectric properties, such as the widely reported d33 charge coefficient, is a good starting point in establishing the potential applicability of piezoceramics. However, piezoceramics are only completely characterized by consistent piezoelectric-elastic-dielectric material coefficient matrices in complex form, i.e., including all [...] Read more.
Achieving good piezoelectric properties, such as the widely reported d33 charge coefficient, is a good starting point in establishing the potential applicability of piezoceramics. However, piezoceramics are only completely characterized by consistent piezoelectric-elastic-dielectric material coefficient matrices in complex form, i.e., including all losses. These matrices, which define the various alternative forms of the constitutive equations of piezoelectricity, are required for reliable virtual prototyping in the design of new devices. To meet this need, ten precise and accurate piezoelectric dielectric and elastic coefficients of the material, including all losses, must be determined for each alternative. Due to the difficulties arising from the coupling of modes when using the resonance method, this complete set of parameters is scarcely reported. Bi0.5Na0.5TiO3-based solid solutions are already commercially available in Europe and Japan. Here, we report a case study of the determination of these sets of material coefficients (d, g, e and h; sE,Dαβ and cE,Dαβ; εTik and εSik; and βTik and βSik), including all losses, of the commercial PIC700 eco-piezoceramic. Plate, disk, and cylinder ceramic resonators of a manageable aspect ratio were used to obtain all the material coefficients. The validation procedure of the matrices is also given by FEA modeling of the considered resonators. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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15 pages, 5360 KiB  
Article
Dielectrophoresis Structurization of PZT/PDMS Micro-Composite for Elastronic Function: Towards Dielectric and Piezoelectric Enhancement
Materials 2021, 14(15), 4071; https://doi.org/10.3390/ma14154071 - 21 Jul 2021
Cited by 9 | Viewed by 2410
Abstract
Piezoelectric materials have been used for decades in the field of sensors as transducers and energy harvesters. Among these, piezoelectric composites are emerging being extremely advantageous in terms of production, costs, and versatility. However, the piezoelectric performances of a composite with randomly dispersed [...] Read more.
Piezoelectric materials have been used for decades in the field of sensors as transducers and energy harvesters. Among these, piezoelectric composites are emerging being extremely advantageous in terms of production, costs, and versatility. However, the piezoelectric performances of a composite with randomly dispersed filler are not comparable with bulk ferroelectric ceramics and electroactive polymers. In order to achieve highly performing and low-cost materials, this work aims to develop flexible composites made of Lead zirconate titanate (PZT) filler in Polydimethylsiloxane (PDMS) matrix, with a specific internal structure called quasi-1–3 connectivity. Such a structure, comprising particles arranged in columns along a preferred direction, is performed through dielectrophoresis by applying an alternating electric field on the composite before and during the polymerization. The developed flexible material could be introduced into complex structures in various application fields, as sensors for structural monitoring. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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13 pages, 3205 KiB  
Article
Machine Learning Identification of Piezoelectric Properties
Materials 2021, 14(9), 2405; https://doi.org/10.3390/ma14092405 - 05 May 2021
Cited by 4 | Viewed by 2450
Abstract
The behavior of a piezoelectric element can be reproduced with high accuracy using numerical simulations. However, simulations are limited by knowledge of the parameters in the piezoelectric model. The identification of the piezoelectric model can be addressed using different techniques but is still [...] Read more.
The behavior of a piezoelectric element can be reproduced with high accuracy using numerical simulations. However, simulations are limited by knowledge of the parameters in the piezoelectric model. The identification of the piezoelectric model can be addressed using different techniques but is still a problem for manufacturers and end users. In this paper, we present the use of a machine learning approach to determine the parameters in the model. In this first work, the main sensitive parameters, c11, c13, c33, c44 and e33 were predicted using a neural network numerically trained by using finite element simulations. Close to one million simulations were performed by changing the value of the selected parameters by ±10% around the starting point. To train the network, the values of a PZT 27 piezoelectric ceramic with a diameter of 20 mm and thickness of 2 mm were used as the initial seed. The first results were very encouraging, and provided the original parameters with a difference of less than 0.6% in the worst case. The proposed approach is extremely fast after the training of the neural network. It is suitable for manufacturers or end users that work with the same material and a fixed number of geometries. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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13 pages, 4702 KiB  
Article
Modeling and Experimental Characterization of Bonding Delaminations in Single-Element Ultrasonic Transducer
Materials 2021, 14(9), 2269; https://doi.org/10.3390/ma14092269 - 27 Apr 2021
Cited by 1 | Viewed by 2261
Abstract
Ultrasonic transducers performance can be seriously deteriorated by loss of adhesion between some constitutive elements such as the active element, the backing, or the matching layer. In the present work, the influence of bonding delaminations on the performance of a single-element ultrasonic transducer, [...] Read more.
Ultrasonic transducers performance can be seriously deteriorated by loss of adhesion between some constitutive elements such as the active element, the backing, or the matching layer. In the present work, the influence of bonding delaminations on the performance of a single-element ultrasonic transducer, which is composed of a piezoelectric disk, a backing, and a matching layer, is studied numerically and experimentally. Based on the positions between layers, two cases, i.e., delaminations between ceramic and backing or between ceramic and matching layer, are considered. Each case involves three different types of delaminations, which are marked as delamination type (DT)-I, II, and III. DT-I, a circular shape delamination, starts from the center and expands towards the peripheric zone; DT-II, an annular shape delamination, starts from the peripheric zone and expands towards the center; DT-III is a sector shape delamination with a given angle. The numerical simulations are performed by the finite element method and the influence of delaminations on the electromechanical admittance (EMA) of the transducer is investigated. 3D printed backings and matching layers are mounted on a PZT sample to assemble delaminated single-element transducers. An impedance analyzer is used for experimental measurements. Comparison between numerical and experimental results shows a reasonable agreement making changes in EMA an interesting indicator to inform about the occurrence and severity of delaminations in a single-element ultrasonic transducer. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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15 pages, 5885 KiB  
Article
Influence of Quenching and Subsequent Annealing on the Conductivity and Electromechanical Properties of Na1/2Bi1/2TiO3-BaTiO3
Materials 2021, 14(9), 2149; https://doi.org/10.3390/ma14092149 - 23 Apr 2021
Cited by 11 | Viewed by 1617
Abstract
Na1/2Bi1/2TiO3-based materials have gained considerable attention for their potential to exhibit giant strain, very-high ionic conductivity comparable to yttria stabilized zirconia or high mechanical quality factor for use in high power ultrasonics. In recent times, quenching Na [...] Read more.
Na1/2Bi1/2TiO3-based materials have gained considerable attention for their potential to exhibit giant strain, very-high ionic conductivity comparable to yttria stabilized zirconia or high mechanical quality factor for use in high power ultrasonics. In recent times, quenching Na1/2Bi1/2TiO3-based compositions have been demonstrated to enhance the thermal depolarization temperature, thus increasing the operational temperature limit of these materials in application. This work investigates the role of quenching-induced changes in the defect chemistry on the dielectric, ferroelectric and piezoelectric properties of quenched Na1/2Bi1/2TiO3-BaTiO3. The quenched samples indeed demonstrate an increase in the bulk conductivity. Nevertheless, while subsequent annealing of the quenched samples in air/oxygen atmosphere reverts back the depolarization behaviour to that of a furnace cooled specimen, the bulk conductivity remains majorly unaltered. This implies a weak correlation between the defect chemistry and enhanced thermal stability of the piezoelectric properties and hints towards other mechanisms at play. The minor role of oxygen vacancies is further reinforced by the negligible (10–15%) changes in the mechanical quality factor and hysteresis loss. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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11 pages, 1534 KiB  
Article
Oxygen Vacancies in Perovskite Oxide Piezoelectrics
Materials 2020, 13(24), 5596; https://doi.org/10.3390/ma13245596 - 08 Dec 2020
Cited by 20 | Viewed by 3619
Abstract
The excellent electro-mechanical properties of perovskite oxide ferroelectrics make these materials major piezoelectrics. Oxygen vacancies are believed to easily form, migrate, and strongly affect ferroelectric behavior and, consequently, the piezoelectric performance of these materials and devices based thereon. Mobile oxygen vacancies were proposed [...] Read more.
The excellent electro-mechanical properties of perovskite oxide ferroelectrics make these materials major piezoelectrics. Oxygen vacancies are believed to easily form, migrate, and strongly affect ferroelectric behavior and, consequently, the piezoelectric performance of these materials and devices based thereon. Mobile oxygen vacancies were proposed to explain high-temperature chemical reactions half a century ago. Today the chemistry-enabled concept of mobile oxygen vacancies has been extrapolated to arbitrary physical conditions and numerous effects and is widely accepted. Here, this popular concept is questioned. The concept is shown to conflict with our modern physical understanding of ferroelectrics. Basic electronic processes known from mature semiconductor physics are demonstrated to explain the key observations that are groundlessly ascribed to mobile oxygen vacancies. The concept of mobile oxygen vacancies is concluded to be misleading. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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13 pages, 3408 KiB  
Article
A Modified Iterative Automatic Method for Characterization at Shear Resonance: Case Study of Ba0.85Ca0.15Ti0.90Zr0.10O3 Eco-Piezoceramics
Materials 2020, 13(7), 1666; https://doi.org/10.3390/ma13071666 - 03 Apr 2020
Cited by 5 | Viewed by 2006
Abstract
Coupling between electrically excited electromechanical resonances of piezoelectric ceramics is undesirable for the purpose of their characterization, since the material models correspond to monomodal resonances. However, coupling takes place quite often and it is unavoidable at the shear resonance of standard in-plane poled [...] Read more.
Coupling between electrically excited electromechanical resonances of piezoelectric ceramics is undesirable for the purpose of their characterization, since the material models correspond to monomodal resonances. However, coupling takes place quite often and it is unavoidable at the shear resonance of standard in-plane poled and thickness-excited rectangular plates. The piezoelectric coefficient e15, the elastic compliance s55E and the dielectric permittivity component ε11S for a piezoelectric ceramic can be determined, including all losses, using the automatic iterative method of analysis of the complex impedance curves for the shear mode of an appropriated resonator. This is the non-standard, thickness-poled and longitudinally excited, shear plate. In this paper, the automatic iterative method is modified. The purpose is to be able to deal with the analysis of the impedance curves of the non-standard plate as the periodic phenomena of coupling and decoupling of the main shear resonance and other resonances takes place. This happens when the thickness of the plate is reduced, and its aspect ratio (width of the excitation (w)/thickness for poling (t)) is increased. In this process, the frequency of the shear resonance also increases and meets those of other plate modes periodically. We aim to obtain the best approach for the shear properties of near coupling and to reveal both their validity and the limitations of the thus-obtained information. Finally, we use a plate of a Ba0.85Ca0.15Ti0.90Zr0.10O3 eco-piezoceramic as a case study. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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Review

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47 pages, 4976 KiB  
Review
Strategies to Improve the Energy Storage Properties of Perovskite Lead-Free Relaxor Ferroelectrics: A Review
Materials 2020, 13(24), 5742; https://doi.org/10.3390/ma13245742 - 16 Dec 2020
Cited by 92 | Viewed by 6565
Abstract
Electrical energy storage systems (EESSs) with high energy density and power density are essential for the effective miniaturization of future electronic devices. Among different EESSs available in the market, dielectric capacitors relying on swift electronic and ionic polarization-based mechanisms to store and deliver [...] Read more.
Electrical energy storage systems (EESSs) with high energy density and power density are essential for the effective miniaturization of future electronic devices. Among different EESSs available in the market, dielectric capacitors relying on swift electronic and ionic polarization-based mechanisms to store and deliver energy already demonstrate high power densities. However, different intrinsic and extrinsic contributions to energy dissipations prevent ceramic-based dielectric capacitors from reaching high recoverable energy density levels. Interestingly, relaxor ferroelectric-based dielectric capacitors, because of their low remnant polarization, show relatively high energy density and thus display great potential for applications requiring high energy density properties. In this study, some of the main strategies to improve the energy density properties of perovskite lead-free relaxor systems are reviewed, including (i) chemical modification at different crystallographic sites, (ii) chemical additives that do not target lattice sites, and (iii) novel processing approaches dedicated to bulk ceramics, thick and thin films, respectively. Recent advancements are summarized concerning the search for relaxor materials with superior energy density properties and the appropriate choice of both composition and processing routes to match various applications’ needs. Finally, future trends in computationally-aided materials design are presented. Full article
(This article belongs to the Special Issue Piezoelectric Ceramics: From Fundamentals to Applications)
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