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Ceramics
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Innovative Processing Routes for Electroactive Materials
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Innovative Processing Routes for Electroactive Materials

A special issue of Ceramics (ISSN 2571-6131).

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 37213

Special Issue Editor

Dr. Giuseppe Viola

E-Mail Website
Guest Editor
Institute for Materials Discovery, University College London, 113 Roberts Building, Malet Place, London WC1E 7JE, UK
Interests: functional materials; electroceramics; energy storage capacitors; piezoelectric devices
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is our pleasure to open submissions for the present Special Issue dedicated to innovative processing routes for the fabrication of electroactive materials, with specific focus on dielectrics, piezoelectrics, ferroelectrics, multiferroics and thermoelectrics. We invite original research contributions in the form of short communications, full-length articles and reviews to share and disseminate the latest developments on the processing of electroactive materials that enable overcoming the difficulties encountered using conventional methods and identifying appropriate processing schedules for the fabrication of novel materials. Technical manuscripts on powder technologies, synthesis procedures and novel sintering techniques, including cold sintering, flash sintering and current assisted sintering, as well as manufacturing routes for mass production that can support industrial-scale processing of novel materials, are considered particularly appropriate for this Special Issue. The main aim is to compile original and insightful papers that can guide materials scientists to solve major processing issues and obtain high-quality materials with desired properties.

Dr. Giuseppe Viola
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Ceramics is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Electroactive materials
  • Innovative manufacturing
  • Powder processing
  • Synthesis
  • Sintering
  • Microstructure
  • Electrical properties

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Published Papers (8 papers)

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Research

Jump to: Review

16 pages, 5771 KiB  
Article
Smart Self-Sensing Piezoresistive Composite Materials for Structural Health Monitoring
by Relebohile George Qhobosheane, Monjur Morshed Rabby, Vamsee Vadlamudi, Kenneth Reifsnider and Rassel Raihan
Ceramics 2022, 5(3), 253-268; https://doi.org/10.3390/ceramics5030020 - 21 Jun 2022
Cited by 5 | Viewed by 2968
Abstract
The use of fiber-reinforced composite materials has widely spread in various sectors, including aerospace, defense, and civil industry. The assessment of these heterogeneous material systems is important for safer and risk-free applications and has contributed to the need for self-sensing composites. This work [...] Read more.
The use of fiber-reinforced composite materials has widely spread in various sectors, including aerospace, defense, and civil industry. The assessment of these heterogeneous material systems is important for safer and risk-free applications and has contributed to the need for self-sensing composites. This work is focused on the development of piezoresistive composites, the prediction of their performance and structural health monitoring (SHM). Additionally, this work unpacks the complexity of carbon nanotubes (CNTs) micro-fabrication and the development of piezoresistive and electromagnetic (EM) waves detection electrodes. Scanning electron microscopy (SEM) was used to characterize the CNTs structure and morphologies. The manufactured CNTs were incorporated in epoxy systems to fabricate glass fiber reinforced polymer (GFRP)-CNTs smart composites with piezoresistive properties. The detection of micro-damage onset and its progression was carried out in mode I, to evaluate the sensitivity of the smart composites to damage development. The change in electrical conductivity of the nanotubes-reinforced composite systems due to localized mechanical strains enabled crack propagation detection. The relationship between crack propagation, fracture toughness, and electrical resistivity of the smart composite was analyzed. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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16 pages, 5986 KiB  
Article
Zn2+-Doped TiO2:WO3 Films Prepared by Electrospinning and Sintering: Microstructural Characterization and Electrical Signature to Moisture Sensing
by Georgenes M. G. Silva, Victor N. S. Leão, Michel F. G. Pereira, Pedro M. Faia and Evando S. Araújo
Ceramics 2021, 4(4), 576-591; https://doi.org/10.3390/ceramics4040041 - 21 Oct 2021
Cited by 9 | Viewed by 2718
Abstract
In this work, Zn2+-doped TiO2:WO3 nanostructured films, with different doping levels, were produced by electrospinning followed by sintering, and tested as potential materials for relative humidity (RH) detection. The materials microstructure was investigated by scanning electron microscopy (SEM), [...] Read more.
In this work, Zn2+-doped TiO2:WO3 nanostructured films, with different doping levels, were produced by electrospinning followed by sintering, and tested as potential materials for relative humidity (RH) detection. The materials microstructure was investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD). The electrical characterization was performed by electrical impedance spectroscopy in the range of 400 HZ–40 MHZ, at 20 °C. The sensors’ sensitivity to moisture was evaluated from the impedance variations in response to changes in RH (10–100%). The analyses confirmed the interaction of water molecules with the oxides surface, and showed that zinc atoms were incorporated into the titanium vacancies in the crystal lattice. All the studied sensors showed a p- to n-type conduction transition taking place at around 40% RH. The nanocomposite with 2 wt% of dopant presented the best sensitivity to moisture, with an impedance variation of about 1 order of magnitude. The results are discussed in relation to the microstructure and fabrication route. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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15 pages, 4547 KiB  
Article
Influence of Isovalent ‘W’ Substitutions on the Structure and Electrical Properties of La2Mo2O9 Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cells
by Tanmoy Paul and Yoed Tsur
Ceramics 2021, 4(3), 502-515; https://doi.org/10.3390/ceramics4030037 - 16 Sep 2021
Cited by 5 | Viewed by 3464
Abstract
Lanthanum molybdenum oxide (La2Mo2O9, LAMOX)-based ion conductors have been used as potential electrolytes for solid oxide fuel cells. The parent compound La2Mo2O9 undergoes a structural phase transition from monoclinic (P21 [...] Read more.
Lanthanum molybdenum oxide (La2Mo2O9, LAMOX)-based ion conductors have been used as potential electrolytes for solid oxide fuel cells. The parent compound La2Mo2O9 undergoes a structural phase transition from monoclinic (P21) to cubic (P213) at 580 °C, with an enhancement in oxide ion conductivity. The cubic phase is of interest because it is beneficial for oxide ion conduction. In search of alternative candidates with a similar structure that might have a stable cubic phase at lower temperatures, we have studied the variations of the crystal structure and ionic conductivity for 25, 50, 62.5 and 75 mol% W substitutions at the Mo site using high-temperature X-ray diffraction, dilatometry, and impedance spectroscopy. Highly dense ceramic samples have been synthesized by solid-state reaction in a two-step sintering process. Low-angle X-ray diffraction and Rietveld refinement confirm the stabilization of the cubic phase for all compounds in the entire temperature range considered. The substitutions of W at the Mo site produce a decrement in the lattice parameter. The thermal expansion coefficients in the high-temperature range of the W-substituted ceramics, as determined by dilatometry, are much higher than that of the unmodified sample. The impedance spectra have been modeled using a modified genetic algorithm within 300–600 °C. A distribution function of the relaxation times is obtained, and the contributions of ohmic drop, grains and grain boundaries to the conductivity have been identified. Overall, our investigation provides information about cationic substitution and insights into the understanding of oxide ion conductivity in LAMOX-based compounds for developing solid oxide fuel cells. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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20 pages, 4330 KiB  
Article
Synthesis and Pressure-Assisted Sintering of CaCu3Ti4O12 Dielectrics
by Jan Petrášek, Pavel Ctibor, Josef Sedláček and Frantisek Lukáč
Ceramics 2021, 4(3), 447-466; https://doi.org/10.3390/ceramics4030033 - 9 Aug 2021
Cited by 5 | Viewed by 2924
Abstract
In this paper, we examined the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics fabricated by various routes and discussed the most important conditions affecting their dielectric behavior. We prepared feedstock powder using a molten salt route and compared it [...] Read more.
In this paper, we examined the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics fabricated by various routes and discussed the most important conditions affecting their dielectric behavior. We prepared feedstock powder using a molten salt route and compared it with a commercial powder. Both powders were sintered using SPS. For some samples, annealing was applied after sintering. Other samples were obtained by high-pressure forming and conventional sintering, using both powders. Phase composition, porosity and microhardness were evaluated in comparison with the literature. The results showed that a sintering temperature just below or equal to 1000 °C should be set for the SPS process. However, the best dielectric characteristics were obtained in samples prepared by high-pressure forming and conventional sintering, which showed a relative permittivity of 22,000 and a loss tangent of 0.13 at 1 MHz. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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16 pages, 4030 KiB  
Article
PEO Infiltration of Porous Garnet-Type Lithium-Conducting Solid Electrolyte Thin Films
by Aamir Iqbal Waidha, Vanita Vanita and Oliver Clemens
Ceramics 2021, 4(3), 421-436; https://doi.org/10.3390/ceramics4030031 - 23 Jul 2021
Cited by 8 | Viewed by 3887
Abstract
Composite electrolytes containing lithium ion conducting polymer matrix and ceramic filler are promising solid-state electrolytes for all solid-state lithium ion batteries due to their wide electrochemical stability window, high lithium ion conductivity and low electrode/electrolyte interfacial resistance. In this study, we report on [...] Read more.
Composite electrolytes containing lithium ion conducting polymer matrix and ceramic filler are promising solid-state electrolytes for all solid-state lithium ion batteries due to their wide electrochemical stability window, high lithium ion conductivity and low electrode/electrolyte interfacial resistance. In this study, we report on the polymer infiltration of porous thin films of aluminum-doped cubic garnet fabricated via a combination of nebulized spray pyrolysis and spin coating with subsequent post annealing at 1173 K. This method offers a simple and easy route for the fabrication of a three-dimensional porous garnet network with a thickness in the range of 50 to 100 µm, which could be used as the ceramic backbone providing a continuous pathway for lithium ion transport in composite electrolytes. The porous microstructure of the fabricated thin films is confirmed via scanning electron microscopy. Ionic conductivity of the pristine films is determined via electrochemical impedance spectroscopy. We show that annealing times have a significant impact on the ionic conductivity of the films. The subsequent polymer infiltration of the porous garnet films shows a maximum ionic conductivity of 5.3 × 10−7 S cm−1 at 298 K, which is six orders of magnitude higher than the pristine porous garnet film. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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11 pages, 4108 KiB  
Article
Tunable Magneto-Dielectric Material for Electrically Small and Reconfigurable Antenna Systems at Vhf Band
by Lotfi Batel, Jean-Luc Mattei, Vincent Laur, Alexis Chevalier and Christophe Delaveaud
Ceramics 2020, 3(3), 276-286; https://doi.org/10.3390/ceramics3030025 - 6 Jul 2020
Cited by 8 | Viewed by 3576
Abstract
The main issue to tune controlled devices by the application of a DC magnetic field comes up against the high value of the field’s intensity required for their implementation. This work presents an implementation of magneto-dielectric materials (MDM) specifically manufactured for their integration [...] Read more.
The main issue to tune controlled devices by the application of a DC magnetic field comes up against the high value of the field’s intensity required for their implementation. This work presents an implementation of magneto-dielectric materials (MDM) specifically manufactured for their integration in antenna devices operating in VHF band. The twofold objective is: (i) reduction in antenna size, (ii) frequency tuning of the antenna using a low intensity magnetic control. A notable permeability variation of MDM samples is observed when the symmetry of the lines of the control field, with an intensity less than 10 Oe, is consistent with the one of the structures in the magnetic domains. The MDM allows a miniaturization of 20% of an inverted-F antenna (IFA) antenna structure, and an agility of about 2.5% for a control field of 1.5 Oe. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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Review

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26 pages, 35312 KiB  
Review
Recent Progress on Electroactive Polymers: Synthesis, Properties and Applications
by Md Hafizur Rahman, Harmony Werth, Alexander Goldman, Yuki Hida, Court Diesner, Logan Lane and Pradeep L. Menezes
Ceramics 2021, 4(3), 516-541; https://doi.org/10.3390/ceramics4030038 - 20 Sep 2021
Cited by 17 | Viewed by 10174
Abstract
Electroactive polymers (EAPs) are an advanced family of polymers that change their shape through electric stimulation and have been a point of interest since their inception. This unique functionality has helped EAPs to contribute to versatile fields, such as electrical, biomedical, and robotics, [...] Read more.
Electroactive polymers (EAPs) are an advanced family of polymers that change their shape through electric stimulation and have been a point of interest since their inception. This unique functionality has helped EAPs to contribute to versatile fields, such as electrical, biomedical, and robotics, to name a few. Ionic EAPs have a significant advantage over electronic EAPs. For example, Ionic EAPs require a lower voltage to activate than electronic EAPs. On the other hand, electronic EAPs could generate a relatively larger actuation force. Therefore, efforts have been focused on improving both kinds to achieve superior properties. In this review, the synthesis routes of different EAP-based actuators and their properties are discussed. Moreover, their mechanical interactions have been investigated from a tribological perspective as all these EAPs undergo surface interactions. Such interactions could reduce their useful life and need significant research attention for enhancing their life. Recent advancements and numerous applications of EAPs in various sectors are also discussed in this review. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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23 pages, 9036 KiB  
Review
The Role of Sacrificial and/or Protective Layers to Improve the Sintering of Electroactive Ceramics: Application to Piezoelectric PZT-Printed Thick Films for MEMS
by Hélène Debéda, Maria-Isabel Rua-Taborda, Onuma Santawitee, Simon Grall, Mario Maglione, U-Chan Chung and Catherine Elissalde
Ceramics 2020, 3(4), 453-475; https://doi.org/10.3390/ceramics3040038 - 16 Nov 2020
Cited by 2 | Viewed by 5368
Abstract
Piezoelectric thick films are of real interest for devices such as ceramic Micro-ElectroMechanical Systems (MEMS) because they bridge the gap between thin films and bulk ceramics. The basic design of MEMS includes electrodes, a functional material, and a substrate, and efforts are currently [...] Read more.
Piezoelectric thick films are of real interest for devices such as ceramic Micro-ElectroMechanical Systems (MEMS) because they bridge the gap between thin films and bulk ceramics. The basic design of MEMS includes electrodes, a functional material, and a substrate, and efforts are currently focused on simplified processes. In this respect, screen-printing combined with a sacrificial layer approach is attractive due to its low cost and the wide range of targeted materials. Both the role and the nature of the sacrificial layer, usually a carbon or mineral type, depend on the process and the final device. First, a sacrificial layer method dedicated to screen-printed thick-film ceramic and LTCC MEMS is presented. Second, the recent processing of piezoelectric thick-film ceramic MEMS using spark plasma sintering combined with a protective layer approach is introduced. Whatever the approach, the focus is on the interdependent effects of the microstructure, chemistry, and strain/stress, which need to be controlled to ensure reliable and performant properties of the multilayer electroceramics. Here the goal is to highlight the benefits and the large perspectives of using sacrificial/protective layers, with an emphasis on the pros and cons of such a strategy when targeting a complex piezoelectric MEMS design. Full article
(This article belongs to the Special Issue Innovative Processing Routes for Electroactive Materials)
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