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Micromachines
Special Issues
Functional Ceramics: From Fundamental Research to Applications
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Functional Ceramics: From Fundamental Research to Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D：Materials and Processing".

Deadline for manuscript submissions: 31 October 2024 | Viewed by 3308

Special Issue Editors

Prof. Dr. Chien-Min Cheng

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Guest Editor
Department of Electronic Engineering, Southern Taiwan University of Science and Technology, Tainan 710301, Taiwan
Interests: electroceramics; thin films; piezoelectric ceramics
Prof. Dr. Kai-Huang Chen

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Guest Editor
Graduate Institute of Electronic Engineering, Cheng-Shiu University, Kaohsiung, Taiwan
Interests: non-volatile resistor random memory devices; ferroelectric memory devices; thin films; functional ceramics applications
Special Issues, Collections and Topics in MDPI journals
Dr. Chih-Lung Tseng

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Guest Editor
Interdisciplinary Program of Green and Information Technology, National Taitung University, Taitung 95092, Taiwan
Interests: optical fiber laser; optoelectronic semiconductor; semiconductor physics; electronic circuit design

Special Issue Information

Dear Colleagues,

Functional ceramics have gradually gained importance in recent years; these interesting materials have been used in electronic devices in many important applications. Functional ceramics is an applied science that studies the design, material composition, material properties, and applications of substances and devices made of functional ceramics. Electronic semiconductor devices and optical coatings are the main applications of functional ceramic thin-film technology today. This technology has a wide range of applications. Much research has used different thin films for computer storage devices, pharmaceuticals, manufacturing thin-film batteries, dye-sensitized solar cells, and more. Due to the relatively high hardness of ceramic materials, such films are used to protect substrates from corrosion, oxidation, and wear. The Special Issue on functional ceramics presents the growth, characteristics, and applications of nanostructured thin films in various domains. We invite contributions from leading groups in the field with the aim of giving a balanced view of the current state of the art in this discipline.

Prof. Dr. Chien-Min Cheng
Prof. Dr. Kai-Huang Chen
Dr. Chih-Lung Tseng
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 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. Micromachines 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 2600 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

  • functional ceramics
  • thin films
  • piezoelectric ceramics
  • computer storage devices
  • pharmaceuticals
  • manufacturing thin-film batteries
  • dye-sensitized solar cells

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Published Papers (4 papers)

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Research

17 pages, 9225 KiB  
Article
Study of the Characteristics of Ba0.6Sr0.4Ti1-xMnxO3-Film Resistance Random Access Memory Devices
by Kai-Huang Chen, Chien-Min Cheng, Ming-Cheng Kao, Yun-Han Kao and Shen-Feng Lin
Micromachines 2024, 15(9), 1143; https://doi.org/10.3390/mi15091143 - 12 Sep 2024
Viewed by 445
Abstract
In this study, Ba0.6Sr0.4Ti1-xMnxO3 ceramics were fabricated by a novel ball milling technique followed by spin-coating to produce thin-film resistive memories. Measurements were made using field emission scanning electron microscopes, atomic force microscopes, X-ray [...] Read more.
In this study, Ba0.6Sr0.4Ti1-xMnxO3 ceramics were fabricated by a novel ball milling technique followed by spin-coating to produce thin-film resistive memories. Measurements were made using field emission scanning electron microscopes, atomic force microscopes, X-ray diffractometers, and precision power meters to observe, analyze, and calculate surface microstructures, roughness, crystalline phases, half-height widths, and memory characteristics. Firstly, the effect of different sintering methods with different substitution ratios of Mn4+ for Ti4+ was studied. The surface microstructural changes of the films prepared by the one-time sintering method were compared with those of the solid-state reaction method, and the effects of substituting a small amount of Ti4+ with Mn4+ on the physical properties were analyzed. Finally, the optimal parameters obtained in the first part of the experiment were used for the fabrication of the thin-film resistive memory devices. The voltage and current characteristics, continuous operation times, conduction mechanisms, activation energies, and hopping distances of two types of thin-film resistive memory devices, BST and BSTM, were measured and studied under different compliance currents. Full article
(This article belongs to the Special Issue Functional Ceramics: From Fundamental Research to Applications)
►▼ Show Figures

Figure 1

Figure 1
<p>Structure diagram of BST- and BSTM-film RRAM devices.</p> Full article ">Figure 2
<p>XRD patterns of the BST material for one-time sintering method and solid-state reaction method.</p> Full article ">Figure 3
<p>FE-SEM images of the BST material for one-time sintering method and solid-state reaction method.</p> Full article ">Figure 4
<p>AFM diagram of BST materials for the solid-state reaction method.</p> Full article ">Figure 5
<p>AFM diagram of BST materials for the one-time sintering method.</p> Full article ">Figure 6
<p>XRD patterns of BSTM materials for different Mn proportions.</p> Full article ">Figure 7
<p>FE-SEM images for different Mn proportions of BSTM materials.</p> Full article ">Figure 8
<p>AFM surface images for different Mn proportions of BSTM materials.</p> Full article ">Figure 9
<p>The <span class="html-italic">I-V</span> curves of BST-film RRAM devices for different compliance currents. (red symbol: oxygen ions).</p> Full article ">Figure 10
<p>The <span class="html-italic">I-V</span> curves of BSTM-film RRAM devices for different compliance currents. (red symbol: oxygen ions).</p> Full article ">Figure 11
<p>The retention and switching cycle properties of BST- and BSTM-film RRAM devices for different compliance currents.</p> Full article ">Figure 12
<p>The reliability properties of BST- and BSTM-film RRAM devices for different compliance currents.</p> Full article ">Figure 13
<p>Conduction mechanism analysis of BST- and BSTM-film RRAM devices for different compliance currents.</p> Full article ">Figure 14
<p>The activation energy versus applied voltage of BST-film RRAM devices for different compliance currents: (<b>a</b>) temperature variation with 0.5 mA compliance current; (<b>b</b>) temperature variation with 10 mA compliance current; (<b>c</b>) electronic activation energy for 0.5 mA compliance current; (<b>d</b>) electronic activation energy for 10 mA compliance current; (<b>e</b>) voltage and activation energy for 0.5 mA compliance current; (<b>f</b>) voltage and activation energy for 10 mA compliance current. (Blue dots: activation energy versus the applied voltage).</p> Full article ">Figure 15
<p>Electron hopping model of BST thin film RRAM devices for the compliance currents of (<b>a</b>) 0.5 mA, and (<b>b</b>) 10 mA.</p> Full article ">Figure 16
<p>The activation energy versus applied voltage of BSTM-film RRAM devices for different compliance currents: (<b>a</b>) temperature variation with 0.5 mA compliance current; (<b>b</b>) temperature variation with 10 mA compliance current; (<b>c</b>) electronic activation energy for 0.5 mA compliance current; (<b>d</b>) electronic activation energy for 10 mA compliance current; (<b>e</b>) voltage and activation energy for 0.5 mA compliance current; (<b>f</b>) voltage and activation energy for 10 mA compliance current. (Blue dots: activation energy versus the applied voltage).</p> Full article ">Figure 17
<p>Electron hopping model of BSTM thin film RRAM devices for the compliance currents of (<b>a</b>) 0.5 mA, and (<b>b</b>) 10 mA.</p> Full article ">
13 pages, 4414 KiB  
Article
The Electric Conductivity of Bi7Fe3Ti3O21 Doped with Gadolinium
by Jolanta Makowska, Diana Szalbot, Małgorzata Adamczyk-Habrajska, Beata Wodecka-Duś and Maciej Chrunik
Micromachines 2024, 15(7), 860; https://doi.org/10.3390/mi15070860 - 30 Jun 2024
Viewed by 599
Abstract
Bi7-xGdxFe3Ti3O21 (x = (0, 0.2, 0.4, 0.6)) bismuth-layered perovskite structure compounds have been successfully prepared by a solid-state reaction. The results of X-ray studies indicate that a single-phase ceramic was obtained, characterized [...] Read more.
Bi7-xGdxFe3Ti3O21 (x = (0, 0.2, 0.4, 0.6)) bismuth-layered perovskite structure compounds have been successfully prepared by a solid-state reaction. The results of X-ray studies indicate that a single-phase ceramic was obtained, characterized by an orthorhombic crystal structure for all compounds within the Fm2m space group. Microstructural analysis revealed that introducing gadolinium to the material altered the grain morphology, resulting in a more rounded grain shape and a somewhat disordered arrangement. Moreover, with higher gadolinium concentrations, there is a noticeable increase in the presence of the number of large plates. Impedance spectroscopy has been used to characterize the electrical properties of Bi7-xGdxFe3Ti3O21 compounds. Full article
(This article belongs to the Special Issue Functional Ceramics: From Fundamental Research to Applications)
►▼ Show Figures

Figure 1

Figure 1
<p>An exemplary pattern obtained from the Rietveld refinement of Bi<sub>6.6</sub>Gd<sub>0.4</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> powders (generated using WinPlotr).</p> Full article ">Figure 2
<p>Microstructure of fractures of ceramic materials and EDS spectra of Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> ceramics for x = (0, 0.2, 0.4, 0.6).</p> Full article ">Figure 2 Cont.
<p>Microstructure of fractures of ceramic materials and EDS spectra of Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> ceramics for x = (0, 0.2, 0.4, 0.6).</p> Full article ">Figure 3
<p>The characteristics of the dependence of the imaginary part of impedance (Z″) on the real part of impedance (Z’) of Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> ceramic materials for x = (0, 0.2, 0.4, 0.6).</p> Full article ">Figure 4
<p>The equivalent circuit used for describing the unmodified Bi<sub>7</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> ceramics.</p> Full article ">Figure 5
<p>The equivalent circuit used for describing the gadolinium-ion-modified Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> for x = (0.2, 0.4, 0.6) ceramics.</p> Full article ">Figure 6
<p>The dependence of the lnR<sub>G</sub> and lnR<sub>GB</sub> obtained from the analysis of impedance spectra as a function of reciprocal temperature in Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> x = (0, 0.2, 0.4, 0.6) ceramics.</p> Full article ">Figure 7
<p>The variation in the total AC conductivity (σ<sub>AC</sub>) as a function of frequency at T = 800 K for the undoped material and that with gadolinium.</p> Full article ">Figure 8
<p>The dependence of DC conductivity, determined based on Jonscher’s law, on the inverse temperature of Bi<sub>7-x</sub>Gd<sub>x</sub>Fe<sub>3</sub>Ti<sub>3</sub>O<sub>21</sub> x = (0, 0.2, 0.4, 0.6) ceramics.</p> Full article ">
17 pages, 14477 KiB  
Article
Antenna Array Design Based on Low-Temperature Co-Fired Ceramics
by Lu Teng, Zhongjun Yu, Dali Zhu, Chengxiang Hao and Na Jiang
Micromachines 2024, 15(6), 669; https://doi.org/10.3390/mi15060669 - 21 May 2024
Viewed by 819
Abstract
With the continuous development of wireless communication technology, the frequency band of 6G communication systems is moving towards higher frequencies such as millimeter waves and terahertz. In such high-frequency situations, wireless transmission requires antenna modules to be provided with characteristics of miniaturization, high [...] Read more.
With the continuous development of wireless communication technology, the frequency band of 6G communication systems is moving towards higher frequencies such as millimeter waves and terahertz. In such high-frequency situations, wireless transmission requires antenna modules to be provided with characteristics of miniaturization, high integration, and high gain, which presents new challenges to the development of antenna technology. In this article, a 4 × 4 antenna array using multilayered low-temperature co-fired ceramic is proposed, operating in W-band, with a feeding network based on substrate-integrated waveguide, and an antenna element formed through the combination of a substrate-integrated cavity and surface parasitic patches, which guaranteed the array to possess the advantages of high integration and high gain. Combined with the substrate-integrated waveguide to a rectangular waveguide transition structure designed in the early stage, a physical array with a standard metal rectangular waveguide interface was fabricated and tested. The test results show that the gain of the antenna array is higher than 18 dBi from 88 to 98 GHz, with a maximum of 20.4 dBi. Full article
(This article belongs to the Special Issue Functional Ceramics: From Fundamental Research to Applications)
►▼ Show Figures

Figure 1

Figure 1
<p>Topology of the antenna array.</p> Full article ">Figure 2
<p>T-junction power divider structure.</p> Full article ">Figure 3
<p>SIW slot feeding structure.</p> Full article ">Figure 4
<p>Step structure at the end of the SIW feeding network.</p> Full article ">Figure 5
<p>Simulation results of the slot feeding structure.</p> Full article ">Figure 6
<p>Antenna unit structure.</p> Full article ">Figure 7
<p>Simulated electric field distribution of the xoz plane in the cavity.</p> Full article ">Figure 8
<p>Simulated antenna pattern of the unit.</p> Full article ">Figure 9
<p>Other patch forms.</p> Full article ">Figure 10
<p>Antenna unit with SIW feeding structure.</p> Full article ">Figure 11
<p>A 4 × 4 array.</p> Full article ">Figure 12
<p>SIW-RWG stepped transition structure.</p> Full article ">Figure 13
<p>Simulation result of SIW-RWG stepped transition structure.</p> Full article ">Figure 14
<p>One-to-two transition structure.</p> Full article ">Figure 15
<p>Simulation results of one-to-two transition structure.</p> Full article ">Figure 16
<p>A 4 × 4 array with an SIW-RWG stepped transition structure.</p> Full article ">Figure 17
<p>A 4 × 4 array with a one-to-two transition structure.</p> Full article ">Figure 18
<p>Layout of the LTCC manufacture process.</p> Full article ">Figure 19
<p>Waveguide adapter.</p> Full article ">Figure 20
<p>Photograph of the LTCC antenna array.</p> Full article ">Figure 21
<p>Photograph of the darkroom test conditions.</p> Full article ">Figure 22
<p>S-parameter test scenario.</p> Full article ">Figure 23
<p>Antenna pattern test scenario.</p> Full article ">Figure 24
<p>S-parameter test results.</p> Full article ">Figure 25
<p>Gain test results.</p> Full article ">Figure 26
<p>Test results of E-plane radiation pattern at 92 GHz.</p> Full article ">Figure 27
<p>Test results of H-plane radiation pattern at 92 GHz.</p> Full article ">Figure 28
<p>Test results of E-plane radiation pattern at 94 GHz.</p> Full article ">Figure 29
<p>Test results of H-plane radiation pattern at 94 GHz.</p> Full article ">Figure 30
<p>Test results of E-plane radiation pattern at 96 GHz.</p> Full article ">Figure 31
<p>Test results of H-plane radiation pattern at 96 GHz.</p> Full article ">
12 pages, 4267 KiB  
Article
Microstructure and Dielectric Properties of Gradient Composite BaxSr1−xTiO3 Multilayer Ceramic Capacitors
by Xiaobing Jili, Libin Gao, Hongwei Chen and Jihua Zhang
Micromachines 2024, 15(4), 470; https://doi.org/10.3390/mi15040470 - 29 Mar 2024
Cited by 1 | Viewed by 1050
Abstract
Multilayer ceramic capacitors (MLCCs) prepared using Ba1−xSrxTiO3 (BST) ceramics exhibit high dielectric constants (~1000), low dielectric loss (<0.01), and high breakdown voltage, with particularly significant tunability in dielectric properties (>50%) and with poor temperature stability. Doping-dominated temperature stability [...] Read more.
Multilayer ceramic capacitors (MLCCs) prepared using Ba1−xSrxTiO3 (BST) ceramics exhibit high dielectric constants (~1000), low dielectric loss (<0.01), and high breakdown voltage, with particularly significant tunability in dielectric properties (>50%) and with poor temperature stability. Doping-dominated temperature stability improvements often result in unintended loss of dielectric properties. A non-doping method has been proposed to enhance the temperature stability of BST capacitors. The composite gradient multilayer (CGML) ceramic capacitors with BaxSr1−xTiO3, where 0.5 < x < 0.8, as the dielectric, were prepared using a tape-casting method and sintered at 1250 °C. There exists a dense microstructure and continuous interface between the BaxSr1−xTiO3 thick film and the Pt electrodes. CGML ceramic capacitors feature a high dielectric constant at 1270, a low dielectric loss of less than 0.007, and excellent frequency and temperature stability. The capacitor showcases remarkable dielectric properties with a substantial tunability of 68% at 100 kV/cm, along with a notably consistent tunability ranging from 20% to 28% at 15 kV/cm across temperatures spanning from 30 to 100 °C, outperforming single-component BST-MLCCs in dielectric performance. Full article
(This article belongs to the Special Issue Functional Ceramics: From Fundamental Research to Applications)
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) The diagram illustrating the fabrication process of the MLCC. (<b>b</b>) Schematic diagram of the BST-MLCC structure. (<b>c</b>) Schematic diagram of the MLCC inner electrode. (<b>d</b>) The finished MLCC with an area of 10 mm × 6 mm.</p> Full article ">Figure 2
<p>(<b>a</b>) XRD patterns of BST thick film samples with different Ba/Sr rations. (<b>b</b>) Magnified portion of the main peak section in the XRD pattern.</p> Full article ">Figure 3
<p>SEM image of the CGML capacitor prepared at 1020 °C (<b>a</b>), interface between layers (<b>b</b>–<b>e</b>), Ba<sub>x</sub>Sr<sub>1−x</sub>TiO<sub>3</sub> (x = 0.8, x = 0.7, x = 0.6, 0.5) grains (<b>f</b>–<b>i</b>), metal platinum internal electrode (<b>j</b>). (<b>k</b>) SEM/EDS of dielectric layers with different compositions.</p> Full article ">Figure 4
<p>Scatter plot of the dielectric constant (<b>a</b>) and dielectric loss (<b>b</b>) of MLCCs and CGMLs with variety frequency. The temperature dependence of <math display="inline"><semantics> <mrow> <msub> <mi>ε</mi> <mi>r</mi> </msub> </mrow> </semantics></math> (<b>c</b>) and tanδ (<b>d</b>) of the MLCC and CGMLs.</p> Full article ">Figure 5
<p>Variation in <math display="inline"><semantics> <mrow> <msub> <mi>ε</mi> <mi>r</mi> </msub> </mrow> </semantics></math> value of a CGML capacitor (<b>a</b>), BST (0.5/0.5)-MLCC (<b>b</b>), and BST (0.8/0.2)-MLCC (<b>c</b>) with respect to the applied electric field at 100 kHz and tunability at 10 kV/cm with respect to the temperature of the BST-MLCC sintered at 1250 °C (<b>d</b>).</p> Full article ">
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