Special Issue "Ceramic Conductors"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: 31 October 2018

Special Issue Editors

Guest Editor
Prof. Dr. Maria Gazda

Gdansk University of Technology, Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Narutowicza 11/12, 80-233 Gdansk, Poland
Website | E-Mail
Interests: proton conducting ceramics; mixed electron-ion conductrs; perovskites; high-temperature superconductors; X-ray diffraction
Guest Editor
Dr. Aleksandra Mielewczyk-Gryń

Gdansk University of Technology, Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Narutowicza 11/12, 80-233 Gdansk, Poland
E-Mail
Interests: proton conducting ceramics; mixed electron-ion conductrs; RE niobates; defect chemistry; thermal analysis

Special Issue Information

Dear Colleagues,

Ceramics is traditionally considered as electrically insulating; however, several groups of modern advanced ceramics are conductors of electric current. Among them, there are high-temperature superconductors, metal-like conducting ceramics, semiconductors, as well as ionically conducting ceramics. The electric and electrochemical properties of conducting ceramics, apart from chemical composition, may depend strongly on their micro/nanostructure, porosity, defect interaction, redox processes, atmosphere composition, etc. Therefore, their properties may be modified through both the powder fabrication and its densification and shaping into products. Moreover, many ceramic materials undergo structural phase transitions. The variety of phenomena related to charge transport in ceramics render them very interesting for practical applications. Indeed, conducting ceramics has been applied in superconducting electromagnets, gas sensors, solid oxide fuel cells, batteries, varistors, memory cells, and other electroceramic devices.

The Special Issue on “Conducting Ceramics” is intended to provide a unique interdisciplinary international forum aimed at presenting and discussion of results concerning fabrication, characterization and properties of conducting ceramics as well as characterization of devices based on conducting ceramics. Scientists working in a wide range of disciplines are invited to contribute to this issue.

Examples of the topics which may be included in the Special Issue on “Conducting Ceramics” are listed under the keywords.

Prof. Dr. Maria Gazda
Dr. Aleksandra Mielewczyk-Gryń
Guest Editors

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 papers will be 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. Crystals is an international peer-reviewed open access monthly 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 1200 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

  • Electronic conductivity and superconductivity of ceramics
  • Ionic ceramic conductors
  • Mixed ceramic conductors
  • Fabrication and shaping of conducting ceramics
  • Electroceramic devices

Published Papers (6 papers)

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Research

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Open AccessArticle Quasi-Equilibrium, Multifoil Platelets of Copper- and Titanium-Substituted Bismuth Vanadate, Bi2V0.9(Cu0.1−xTix)O5.5−δ, by Molten Salt Synthesis
Crystals 2018, 8(4), 170; https://doi.org/10.3390/cryst8040170
Received: 11 March 2018 / Revised: 9 April 2018 / Accepted: 12 April 2018 / Published: 17 April 2018
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Abstract
10% copper-substituted (BiCUVOX/Bi2V0.9Cu0.1O5.5−δ) and 5% copper/titanium double-substituted bismuth vanadate (BiCUTIVOX/Bi2V0.9(Cu0.05Ti0.05)O5.5−δ) platelets were formed by molten salt synthesis (MSS) using a eutectic KCl/NaCl salt mixture. The
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10% copper-substituted (BiCUVOX/Bi2V0.9Cu0.1O5.5−δ) and 5% copper/titanium double-substituted bismuth vanadate (BiCUTIVOX/Bi2V0.9(Cu0.05Ti0.05)O5.5−δ) platelets were formed by molten salt synthesis (MSS) using a eutectic KCl/NaCl salt mixture. The product was phase-pure within the limits of X-ray diffraction. The size and form of the platelets could be controlled by changing the heating temperature and time. The crystallite growth rate at a synthesis temperature of 650 °C and the activation energy for grain growth were determined for BICUTIVOX, which experienced inhibited growth compared to BICUVOX. Quasi-equilibrium, multifoil shapes consisting of lobes around the perimeter of the platelets were observed and explained in the context of relative two-dimensional nucleation and edge growth rates. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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Open AccessArticle Crystal Structure, Hydration, and Two-Fold/Single-Fold Diffusion Kinetics in Proton-Conducting Ba0.9La0.1Zr0.25Sn0.25In0.5O3−a Oxide
Crystals 2018, 8(3), 136; https://doi.org/10.3390/cryst8030136
Received: 15 February 2018 / Revised: 12 March 2018 / Accepted: 13 March 2018 / Published: 16 March 2018
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Abstract
In this work, hydration kinetics related to the incorporation of water into proton-conducting Ba0.9La0.1Zr0.25Sn0.25In0.5O3−a perovskite-type oxide are presented, with a recorded transition on temperature from a single-fold to a two-fold behavior. This
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In this work, hydration kinetics related to the incorporation of water into proton-conducting Ba0.9La0.1Zr0.25Sn0.25In0.5O3−a perovskite-type oxide are presented, with a recorded transition on temperature from a single-fold to a two-fold behavior. This can be correlated with an appearance of the electronic hole component of the conductivity at high temperatures. The collected electrical conductivity relaxation data allowed to calculate chemical diffusion coefficient D and surface exchange reaction coefficient k, as well as respective activation energies of their changes on temperature. Presented results are supplemented with a systematic characterization of the structural properties of materials synthesized at different temperatures, amount of incorporated water after hydration in different conditions, influence of water content on the crystal structure, as well as electrical conductivity in dry, H2O- and D2O-containing air, which enabled to evaluate proton (deuterium) conductivity. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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Open AccessArticle Application of La-Doped SrTiO3 in Advanced Metal-Supported Solid Oxide Fuel Cells
Crystals 2018, 8(3), 134; https://doi.org/10.3390/cryst8030134
Received: 31 January 2018 / Revised: 9 March 2018 / Accepted: 10 March 2018 / Published: 13 March 2018
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Abstract
Composite materials frequently allow the drawbacks of single components to be overcome thanks to a synergistic combination of material- and structure-specific features, leading to enhanced and also new properties. This is the case of a metallic-ceramic composite, a nickel-chromium-aluminum (NiCrAl) foam impregnated with
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Composite materials frequently allow the drawbacks of single components to be overcome thanks to a synergistic combination of material- and structure-specific features, leading to enhanced and also new properties. This is the case of a metallic-ceramic composite, a nickel-chromium-aluminum (NiCrAl) foam impregnated with La-doped Strontium Titanate (LST). This particular cermet has very interesting properties that can be used in different fields of application, namely: mechanical robustness provided by the metal foam; and chemical stability in harsh conditions of temperature and atmosphere by promotion of a thin protective layer of alumina (Al2O3); high electronic conductivity given by a percolating ceramic conducting phase, i.e., La-doped Strontium Titanate. In this paper, its application as a current collector in a metal-supported Solid Oxide Fuel Cells (SOFC) was studied. Firstly, the electronic properties of different compositions, stoichiometric and under stoichiometric, of LST were analyzed to choose the best one in terms of conductivity and phase purity. Then, LST chemical stability was studied in the presence of Al2O3 at different temperatures, gas compositions and aging times. Finally, stability and conductivity of LST-impregnated NiCrAl foam composite materials were measured, and LST was found to be fully compatible with the NiCrAl foam, as no reactions were detected in oxidizing and reducing atmosphere after up to 300 h operation at 750 °C and 900 °C between the Al2O3 layer and LST. Results showed that the composite is suitable as a current collector in innovative designs of metal-supported SOFC, like the Evolve cell, in which the metallic part is supposed not only to provide the structural stability to the cell, but also to play the role of current collector due to the impregnation of ceramic material. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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Open AccessArticle Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions
Crystals 2018, 8(3), 122; https://doi.org/10.3390/cryst8030122
Received: 24 January 2018 / Revised: 1 March 2018 / Accepted: 2 March 2018 / Published: 5 March 2018
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Abstract
Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and
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Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics, aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y 3 + ions into the cubic structure of SrF 2 . As compared to pure nanocrystalline SrF 2 the ionic conductivity of Sr 1 x Y x F 2 + x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10 5 S cm 1 at 450 K. We discuss the effect of YF 3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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Graphical abstract

Open AccessArticle Effect of MnO2 Concentration on the Conductivity of Ce0.9Gd0.1MnxO2−δ
Crystals 2018, 8(1), 40; https://doi.org/10.3390/cryst8010040
Received: 15 November 2017 / Revised: 12 January 2018 / Accepted: 15 January 2018 / Published: 17 January 2018
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Abstract
Samples with the composition Ce0.9Gd0.1MnxO2−δ with x = 0.01, 0.02, and 0.05 Mn-addition were prepared by mixed oxide route from Ce0.9Gd0.1O2−δ and MnO2 and sintered at 1300 °C. The electronic
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Samples with the composition Ce0.9Gd0.1MnxO2−δ with x = 0.01, 0.02, and 0.05 Mn-addition were prepared by mixed oxide route from Ce0.9Gd0.1O2−δ and MnO2 and sintered at 1300 °C. The electronic conductivity was measured using a modified Hebb-Wagner technique, the electrical conductivity was investigated by impedance spectroscopy, and oxygen permeation was measured for the sample with x = 0.05. An increase of the electronic partial conductivity with increasing Mn addition was observed, which can be attributed to an additional Mn 3d-related state between the top of the valence band and the bottom of the Ce 4f band. The grain boundary conductivity was found to be suppressed for low Mn contents, but enhanced for the sample with x = 0.05. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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Review

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Open AccessReview Thermal and Chemical Expansion in Proton Ceramic Electrolytes and Compatible Electrodes
Crystals 2018, 8(9), 365; https://doi.org/10.3390/cryst8090365
Received: 18 August 2018 / Revised: 5 September 2018 / Accepted: 6 September 2018 / Published: 14 September 2018
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Abstract
This review paper focuses on the phenomenon of thermochemical expansion of two specific categories of conducting ceramics: Proton Conducting Ceramics (PCC) and Mixed Ionic-Electronic Conductors (MIEC). The theory of thermal expansion of ceramics is underlined from microscopic to macroscopic points of view while
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This review paper focuses on the phenomenon of thermochemical expansion of two specific categories of conducting ceramics: Proton Conducting Ceramics (PCC) and Mixed Ionic-Electronic Conductors (MIEC). The theory of thermal expansion of ceramics is underlined from microscopic to macroscopic points of view while the chemical expansion is explained based on crystallography and defect chemistry. Modelling methods are used to predict the thermochemical expansion of PCCs and MIECs with two examples: hydration of barium zirconate (BaZr1−xYxO3−δ) and oxidation/reduction of La1−xSrxCo0.2Fe0.8O3−δ. While it is unusual for a review paper, we conducted experiments to evaluate the influence of the heating rate in determining expansion coefficients experimentally. This was motivated by the discrepancy of some values in literature. The conclusions are that the heating rate has little to no effect on the obtained values. Models for the expansion coefficients of a composite material are presented and include the effect of porosity. A set of data comprising thermal and chemical expansion coefficients has been gathered from the literature and presented here divided into two groups: protonic electrolytes and mixed ionic-electronic conductors. Finally, the methods of mitigation of the thermal mismatch problem are discussed. Full article
(This article belongs to the Special Issue Ceramic Conductors)
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