Special Issue "Electroceramic Materials"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Electronic Materials".

Deadline for manuscript submissions: 30 September 2020.

Special Issue Editor

Dr. Antonio Feteira
Website
Guest Editor
Sheffield Hallam University, Sheffield, UK
Interests: multiferroics, ferroelectrics, piezoelectrics, energy storage, ceramics, microwave resonators, NTC thermistors, thermoelectrics, sensors, actuators, semiconductor oxides, photoferroelectrics, perovskite oxides, lead free ceramics, AC impedance, electron microscopy, processing of ceramics

Special Issue Information

Dear Colleagues,

Electroceramics are at the heart of modern electronics because they afford an unmatchable range of electrical, magnetic and optical properties, which underpin the deployment of new technologies. Indeed, nowadays electroceramics are ubiquitous in the technical, scientific, industrial and consumer arenas. Nevertheless, the ever increasing trend towards further miniaturisation of electronic devices is demanding new and improved electroceramics. Simultaneously, in response to raw materials scarcity and environmental concerns research into electroceramics has been forced to take a more sustainable path. Innovative processing and manufacture of electroceramics has also seen extraordinary advances, with the deployment of complex structures with novel combinations of materials, to create innovative products for both the consumer and industrial markets. In a foreseeable future, developments in the electroceramics field can be expected to be driven by implementation of multiscale modelling for optimal design. In particular tailoring of the local structure may enable new functionalities. These three factors have promoted a good wealth of fundamental and applied research into ceramics materials with potential to meet stringent requirements placed by technological areas ranging from wireless communication, energy storage, sensors and actuators, just to mention a few.

Dr. Antonio Feteira
Guest Editor

Manuscript Submission Information

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Keywords

  • Pb-free piezoelectrics
  • ceramic microwave resonators
  • LTCC
  • thermoelectrics
  • ferroelectrics
  • PTCR
  • NTC
  • energy storage
  • local structure
  • processing
  • ionic conductors
  • batteries

Published Papers (8 papers)

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Research

Open AccessArticle
Chemical and Physical Properties of the BLT4 Ultra Capacitor—A Suitable Material for Ultracapacitors
Materials 2020, 13(3), 659; https://doi.org/10.3390/ma13030659 - 02 Feb 2020
Cited by 1Correction
Abstract
This paper describes the properties of a lead-free ceramic material based on barium titanate, designed for the construction of ultracapacitors and sensors used in mechatronic systems. The admixture of lanthanum (La3+) served as a modifier. The ceramic powders were obtained by [...] Read more.
This paper describes the properties of a lead-free ceramic material based on barium titanate, designed for the construction of ultracapacitors and sensors used in mechatronic systems. The admixture of lanthanum (La3+) served as a modifier. The ceramic powders were obtained by the solid phase reaction method (conventional method—mixed oxides method—MOM). Technological conditions of the synthesis process were determined on the basis of thermal analysis. The obtained samples are characterized, at room temperature (Tr < TC), by a single-phase tetragonal structure and a P4mm space group. Properly developed large grains (d = 5 µm) contributed to the increase in electric permittivity, the maximum value of which is at the level of εm ≈ 112,000, as well as to a strong decrease in specific resistance in the ferroelectric phase, whereas above the Curie temperature, by creating a potential barrier at their boundaries, there was a a rapid increase in resistivity. The temperature coefficient of resistance of the obtained posistor is 10.53%/K. The electrical properties of the obtained ceramics were examined using impedance spectroscopy. In order to analyze the obtained results, a method of comparing the behavior of the real object and its replacement system in a specific frequency region was used, whereas the Kramer–-Kroning (K–K) test was used to determine the consistency of the measured data. The proper selection of the stoichiometry and synthesis conditions resulted in the creation of an appropriate concentration of donor levels and oxygen gaps, which in turn resulted in a significant increase in the value of electrical permittivity, with small values of the angle of dielectric loss tangent. This fact predisposes the discussed material for certain applications (in the construction of ultracapacitors, among others). Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Preparation and Dielectric Properties of K1/2Na1/2NbO3 Ceramics Obtained from Mechanically Activated Powders
Materials 2020, 13(2), 401; https://doi.org/10.3390/ma13020401 - 15 Jan 2020
Abstract
Alkaline based materials have been considered as a replacement for environmentally harmful Pb(Zr,Ti)O3 (PZT) electro-ceramics. In this paper, the K1/2Na1/2NbO3 (KNN) ceramics were prepared in a three stage process: first Nb2O5, Na2 [...] Read more.
Alkaline based materials have been considered as a replacement for environmentally harmful Pb(Zr,Ti)O3 (PZT) electro-ceramics. In this paper, the K1/2Na1/2NbO3 (KNN) ceramics were prepared in a three stage process: first Nb2O5, Na2CO3, and K2CO3 were milled in a high energy mill (shaker type) for different periods, between 25 h and 100 h, consecutively a solid state reaction was carried out at 550 °C. Finally, the uniaxially pressed samples were sintered at 1000 °C. The reaction temperature is lower for mechanically activated powders than in the case of the conventional solid-state method. The ceramic samples, prepared from the mechanically activated powders, were investigated by dielectric spectroscopy. The influence of the duration of the mechanical activation on the properties of the ceramic materials, e.g., ceramic microstructures, phase transition temperatures, character of the temperature dependences of dielectric permittivity, are discussed. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Sintering Behaviors, Microstructure, and Microwave Dielectric Properties of CaTiO3–LaAlO3 Ceramics Using CuO/B2O3 Additions
Materials 2019, 12(24), 4187; https://doi.org/10.3390/ma12244187 - 13 Dec 2019
Abstract
The effect of CuO/B2O3 additions on the sintering behaviors, microstructures, and microwave dielectric properties of 0.95LaAlO3–0.05CaTiO3 ceramics is investigated. It is found that the sintering temperatures are lowered efficiently from 1600 °C to 1350 °C, as 1 [...] Read more.
The effect of CuO/B2O3 additions on the sintering behaviors, microstructures, and microwave dielectric properties of 0.95LaAlO3–0.05CaTiO3 ceramics is investigated. It is found that the sintering temperatures are lowered efficiently from 1600 °C to 1350 °C, as 1 wt % CuO, 1 wt % B2O3, and 0.5 wt % CuO +0.5 wt % B2O3 are used as the sintering aids due to the appearance of the liquid phase sintering. The microwave dielectric properties of 0.95LaAlO3–0.05CaTiO3 ceramics with the sintering aid additions are strongly related to the densification and the microstructure of the sintered ceramics. At the sintering temperature of 1300 °C, the 0.95LaAlO3–0.05CaTiO3 ceramic with 0.5 wt % CuO + 0.5 wt % B2O3 addition shows the best dielectric properties, including a dielectric constant (εr) of 21, approximate quality factor (Q × f) of 22,500 GHz, and a temperature coefficient of the resonant frequency (τf) of −3 ppm/°C. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Comparison of Electrophysical Properties of PZT-Type Ceramics Obtained by Conventional and Mechanochemical Methods
Materials 2019, 12(20), 3301; https://doi.org/10.3390/ma12203301 - 11 Oct 2019
Cited by 1
Abstract
In the paper, the multicomponent PZT-type ceramics with Pb(Zr0.49Ti0.51)0.94Mn0.015Sb0.01W0.015Ni0.03O3 composition have been obtained by conventional and mechanochemical methods. With conventional ceramic technology, PZT-type ceramics have been synthesized by [...] Read more.
In the paper, the multicomponent PZT-type ceramics with Pb(Zr0.49Ti0.51)0.94Mn0.015Sb0.01W0.015Ni0.03O3 composition have been obtained by conventional and mechanochemical methods. With conventional ceramic technology, PZT-type ceramics have been synthesized by the method of calcination powder (850 °C/4 h). Instead of this step, the mechanochemical synthesis process for different milling periods (15 h, 25 h, 50 h, 75 h) has been applied for a second batch of samples. To obtain the dense PZT-type ceramic samples, powders have been sintered by free sintering method at conditions of 1150 °C/2 h. Studies have shown that the perovskite structure of the PZT-type material is formed during mechanochemical activation of powders during the technological process at low temperature. The application of the mechanochemical synthesis to obtain the PZT-type materials also allows shortening of the technological process, and the useful electrophysical properties of ceramic samples are not reduced at the same time. The presented results have confirmed that the investigated materials can be used in microelectronic applications, especially as elements of actuators and piezoelectric transducers. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessFeature PaperArticle
Temperature Stable Cold Sintered (Bi0.95Li0.05)(V0.9Mo0.1)O4-Na2Mo2O7 Microwave Dielectric Composites
Materials 2019, 12(9), 1370; https://doi.org/10.3390/ma12091370 - 27 Apr 2019
Cited by 8
Abstract
Dense (Bi0.95Li0.05)(V0.9Mo0.1)O4-Na2Mo2O7 (100−x) wt.% (Bi0.95Li0.05)(V0.9Mo0.1)O4 (BLVMO)-x wt.% Na2Mo2O7 (NMO) composite ceramics were successfully fabricated [...] Read more.
Dense (Bi0.95Li0.05)(V0.9Mo0.1)O4-Na2Mo2O7 (100−x) wt.% (Bi0.95Li0.05)(V0.9Mo0.1)O4 (BLVMO)-x wt.% Na2Mo2O7 (NMO) composite ceramics were successfully fabricated through cold sintering at 150 °C under at 200 MPa for 30 min. X-ray diffraction, back-scattered scanning electron microscopy, and Raman spectroscopy not only corroborated the coexistence of BLVMO and NMO phases in all samples, but also the absence of parasitic phases and interdiffusion. With increasing NMO concentration, the relative pemittivity (εr) and the Temperature Coefficient of resonant Frequency (TCF) decreased, whereas the Microwave Quality Factor (Qf) increased. Near-zero TCF was measured for BLVMO-20wt.%NMO composites which exhibited εr ~ 40 and Qf ~ 4000 GHz. Finally, a dielectric Graded Radial INdex (GRIN) lens was simulated using the range of εr in the BLVMO-NMO system, which predicted a 70% aperture efficiency at 26 GHz, ideal for 5G applications. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Intentional Carrier Doping to Realize n-Type Conduction in Zintl Phases Eu5−yLayIn2.2Sb6
Materials 2019, 12(2), 264; https://doi.org/10.3390/ma12020264 - 15 Jan 2019
Cited by 1
Abstract
Due to the tunable electrical transport properties and lower thermal conductivity, Zintl phase compounds have been considered as a promising candidate for thermoelectric applications. Most Sb-based Zintl compounds exhibit essentially p-type conduction as result of the cation vacancy. Herein, n-type Zintl [...] Read more.
Due to the tunable electrical transport properties and lower thermal conductivity, Zintl phase compounds have been considered as a promising candidate for thermoelectric applications. Most Sb-based Zintl compounds exhibit essentially p-type conduction as result of the cation vacancy. Herein, n-type Zintl phases Eu5−yLayIn2.2Sb6 has been successfully synthesized via controlling the vacancy defect combined with intentional electron doping. Excess of In would occupy the vacancy while La doping enables the electron to be the major carrier at the measured temperate range, realizing the n-type conduction for Eu5−yLayIn2.2Sb6 (y ≥ 0.04). Meanwhile, the thermal conductivity of Eu5−yLayIn2.2Sb6 reduces from 0.90 W/mK to 0.72 W/mK at 583 K derived from the La doping-induced disorder. The maximum thermoelectric figure of merit zT = 0.13 was obtained. This work firstly realizes the n-type conduction in Eu5In2Sb6, which sheds light on the strategy to synthesize n-type Zintl thermoelectric materials and promotes the practical applications of Zintl thermoelectric devices. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Electric Current Dependent Fracture in GaN Piezoelectric Semiconductor Ceramics
Materials 2018, 11(10), 2000; https://doi.org/10.3390/ma11102000 - 16 Oct 2018
Cited by 1
Abstract
In this paper, the fracture behavior of GaN piezoelectric semiconductor ceramics was investigated under combined mechanical and electric loading by using three-point bending tests and numerical analysis. The experimental results demonstrate that, in contrast to traditional insulating piezoelectric ceramics, electric current is a [...] Read more.
In this paper, the fracture behavior of GaN piezoelectric semiconductor ceramics was investigated under combined mechanical and electric loading by using three-point bending tests and numerical analysis. The experimental results demonstrate that, in contrast to traditional insulating piezoelectric ceramics, electric current is a key factor in affecting the fracture characteristics of GaN ceramics. The stress, electric displacement, and electric current intensity factors were numerically calculated and then a set of empirical formulae was obtained. By fitting the experimental data, a fracture criterion under combined mechanical and electrical loading was obtained in the form of an ellipsoid function of intensity factors. Such a fracture criterion can be extended to predict the failure behavior of other piezoelectric semiconductors or devices with a crack, which are useful in their reliability design and applications. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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Open AccessArticle
Reliability of X7R Multilayer Ceramic Capacitors During High Accelerated Life Testing (HALT)
Materials 2018, 11(10), 1900; https://doi.org/10.3390/ma11101900 - 04 Oct 2018
Cited by 3
Abstract
Multilayer ceramic capacitors (MLCC) are essential components for determining the reliability of electronic components in terms of time to failure. It is known that the reliability of MLCCs depends on their composition, processing, and operating conditions. In this present work, we analyzed the [...] Read more.
Multilayer ceramic capacitors (MLCC) are essential components for determining the reliability of electronic components in terms of time to failure. It is known that the reliability of MLCCs depends on their composition, processing, and operating conditions. In this present work, we analyzed the lifetime of three similar X7R type MLCCs based on BaTiO3 by conducting High Accelerated Life Tests (HALT) at temperatures up to 200 °C at 400 V and 600 V. The results were adjusted to an Arrhenius equation, which is a function of the activation energy (Ea) and a voltage stress exponent (n), in order to predict their time to failure. The values of Ea are in the range of 1–1.45 eV, which has been reported for the thermal failure and dielectric wear out of BaTiO3-based dielectric capacitors. The stress voltage exponent value was in the range of 4–5. Although the Ea can be associated with a failure mechanism, n only gives an indication of the effect of voltage in the tests. It was possible to associate those values with each type of tested MLCC so that their expected life could be estimated in the range of 400–600 V. Full article
(This article belongs to the Special Issue Electroceramic Materials)
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