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Special Issue Editors

Prof. Dr. José Francisco Fernández

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Guest Editor

Ceramic for Smart System Group, Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049 Madrid, Spain
Interests: lead-free piezoelectric ceramics; ceramic processing; raman spectroscopy

Dr. Fernando Rubio-Marcos

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Guest Editor

Department of Electroceramics, Instituto de Cerámica y Vidrio – CSIC, 28049 Madrid, Spain
Interests: ferroelectricity; photoferroelectrics; piezoelectricity; light-induced phenomena; ceramic materials; synthesis; properties and applications

Special Issue Information

Dear Colleagues,

Lead-free piezoceramics have been extensively investigated in the past decade because of the need to find a promising candidate for replacing lead-based ones. The trigger of the frantic pace into lead-free piezoceramics research can be awarded to a publication by Saito et al. in 2004 (Nature 2004, 432, 84-87), which opened up the real possibility of replacing lead-containing piezoceramics, represented by Pb(Zr,Ti)O₃, PZT, with non-toxic alternatives. Three main solid solution families have been widely recognized as potential environmentally-friendly candidates: (K,Na)NbO₃, KNN-based, (Bi,Na)TiO₃, BNT-based, and (Ba,Ca)(Zr,Ti)O₃, BCZT-based, materials. In addition, a fourth family based on Aurivillius structures (Bi-based layered structure) with properties, with which PZT cannot compete, but has proven interesting in applications working at high temperaturas, must be included.

Many novel lead-free piezoceramics have been developed since then by manipulating the doping, morphotropic phase boundary, MPB, and/or Polymorphic phase boundary, PPB, as well as microstructure. Physical chemistry effects all of these, enabling, for example, the tuning and engineering of the functional response of these materials. This Special Issue broadly tries to cover the intrinsic and extrinsic aspects of lead-free piezoceramics, including their synthesis and processing, chemical and microstructure characterization, theory and modelling of their physical properties, and their future practical applications. Emphasis is put on the systematic review of the major developments in the field of lead-free piezoceramics, as well on some suggestions for the future development of new materials, will also be addressed.

Prof. Dr. José Francisco Fernández
Dr. Fernando Rubio-Marcos
Guest Editors

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Keywords

Lead-free piezoelectric
Phase boundary
Piezoelectricity
Physical mechanisms

Published Papers (2 papers)

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Research

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5706 KiB

Open AccessArticle

Dielectric and Impedance Analysis on the Electrical Response of Lead-Free Ba_1−xCa_xTi_0.9Zr_0.1O₃ Ceramics at High Temperature Range

by Armando Reyes-Montero, Paola Ramos-Alvarez, Amador M. González, Rigoberto López-Juárez and María Elena Villafuerte-Castrejón

Appl. Sci. 2017, 7(3), 214; https://doi.org/10.3390/app7030214 - 23 Feb 2017

Cited by 19 | Viewed by 5798

Abstract

Ba_1−xCa_xTi_0.9Zr_0.1O₃ (x = 0.10, 0.15, 0.18) solid solutions were synthesized by the conventional solid-state method. A perovskite-type structure was determined using the X-ray diffraction (XRD) technique. The addition of Ca²⁺ reduced the grain size (22.6, 17.9 and 13.3 μm, respectively) for all well-sintered ceramics (≈98%). Moreover, the stability temperature ranges for the tetragonal phase were promoted by displacing the ferroelectric-ferroelectric phase’s transition temperatures while T_C was maintained (86 °C). The electrical performance of the material improved as the stoichiometric composition was positioned near the morphotropic phase boundary (x = 0.15): ε_r ≈ 16,500 (T_C) at 1 kHz. For T > T_C, a thermally activated relaxation process occurred. In addition, the bulk and grain boundary processes were responsible for the conduction mechanisms. The composition x = 0.15 showed an activation energy of Ea = 1.49 eV with a maximum conductivity of σ_max = 2.48 × 10⁻² S·cm⁻¹ at 580 °C. Systematic studies at high temperature for dielectric properties were accomplished for analyzing electrical inhomogeneities associated with the grain, grain boundaries or surfaces, which are important for device design and a fundamental electrical characterization. Full article

(This article belongs to the Special Issue A Perspective on the Design of Lead-Free Piezoceramics)

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Review

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16 pages, 7719 KiB

Open AccessFeature PaperReview

Review and Perspectives of Aurivillius Structures as a Lead-Free Piezoelectric System

by Alberto Moure

Appl. Sci. 2018, 8(1), 62; https://doi.org/10.3390/app8010062 - 03 Jan 2018

Cited by 89 | Viewed by 7488

Abstract

According to the EU-Directives 2002/95/EC, 2002/96/EC, lead-based piezoceramics must be substituted in the future with more environmentally friendly alternatives, only when a reliable alternative is found. This is why an increasing interest has grown in the research community to find lead free piezoelectric materials that fulfil the requirements for this substitution. Different families of compounds have been shown to be possible candidates for this use, such as bismuth and niobates based perovskites, pyrochlores, etc. However, a material with piezoelectric coefficients similar to those of PZT (lead zirconate titanate, Pb[Zr_xTi_1-x]O₃) has not been yet found. Besides, each of these families has its specific characteristics in terms of remnant polarization, coercive field or application temperature. Thus, the choice of each material should be made according to the specific needs of the application. In this sense, Aurivillius-type structure materials (also known as Bismuth Layered Structure Ferroelectrics, BLSF) can take advantage of their specific properties for uses as Lead Free Piezoelectric systems. Some of them have a high Curie temperature, which make them good candidates to be used as high temperature piezoelectrics; high coercive fields, which facilitates their use as actuators; or a high switching fatigue resistance, which can be useful for future applications as Ferroelectric Random Access Memories (FERAM). Full article

(This article belongs to the Special Issue A Perspective on the Design of Lead-Free Piezoceramics)

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