Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein

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

Deadline for manuscript submissions: 31 December 2024 | Viewed by 11409

Special Issue Editor


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Guest Editor
Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, 2 Pine Street, Alfred, NY 14802-1296, USA
Interests: transparent ceramics for optical and photonic applications; synthesis and characterization of nanostructured materials for energy and biomedical applications

Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to the domain of transparent ceramics ( TCs); passive or active ones (owing to controlled doping—able to induce designed spectral behavior). It intends to treat topics such as the optimization of all aspects of TC fabrication-related engineering and the introduction of new processing techniques. There is also interest in studies devoted to performance level enhancement of current products (commercial and in prototype stage), relevant characterization techniques (concerning fabrication or performance estimation), and new applications. In many cases, the usefulness of a TC is owed to an adequate design of the dopants package and/or a suitable matching of it with the transparent host. Therefore, works dealing with theoretical and/or applied transition metal cations (TMC), rare-earth (RE) spectroscopy, optical, EPR, Raman, etc., are welcome. So are results regarding host characterization refinements—such as more accurate site symmetry determinations—relevant for dopant accommodation in the host lattice.

The issue also intends to honor Dr. Adrian Goldstein (former head of the Israel Ceramics and Silicates Institute) for his significant contribution to the development of the TC domain. Below, we offer a list of some of the topics studied by the researcher honored. For instance, together with Dr. Andreas Krell (former IKTS-Dresden senior researcher), Dr. Goldstein realized the fact that full ceramics sinterability is obtained more as a result of actions taken in the stage of green-body forming than during sintering. Thus, he demonstrated that an ordered array (obtained by slow gravitational or fast centrifugal deposition) of amorphous micron size cvasi-monodisperse—spherical micron silica particles arranged in a compact packing maintained over large specimen volumes—allows densification fast enough (obtained by MW heating) to generate transparent bulk specimens without crystallization. Arranging, in the same manner, suitable MgAl2O4 powder, highly transparent specimens were obtained via sintering (pressureless + HIP) at temperatures around 1300 oC, viz. many hundreds of degrees lower than is necessary to densify conventional green bodies. He also discovered that, in phosphate glasses, the addition of alkaline-earth metals, as opposed to alkaline ones, reduces the electron donor ability (basicity) of oxide ions. Based on this effect, Cu0-based phosphate stable glasses could be obtained without Sn addition and a striking stage. An interesting finding relates to the accommodation of d1 type cations in oxide glasses. Many such ions (Ti3+, VO2+, Nb4+, Mo5+ and W5+) have in common the tendency to form C4v complexes in oxide glass hosts; the tendency increases with an increase of the oxidation state. Dr. Adrian Goldstein was the first (1998) to obtain transparent spinel via MW sintering (followed by HIPing) and ZnAl2O4 spinel as a transparent ceramic. He identified the main parasitic, reducing incident EMR beams intensity when interacting with spinel or YAG. He determined the mechanisms (promoting or impeding densification) operating when LiF is added to spinel for full densification via hot pressing. Dr. Goldstein also participated in the development of saturable absorber type, Co2+ based Q-switches for Er3+ lasers. Regarding the interaction of transition metal dopants in glasses, he discovered a redox interaction between Cr3+ and Cu2+.

The list of his publications includes, among others, an invited paper on transparent ceramics (J. Amer. Ceram. Soc. 2016) and eight invited lectures on the same topic. A more extensive review of the domain was offered in the book written by Dr. Adrian Goldstein:

Goldstein A., Krell A. and Burshtein Z. “Transparent Ceramics: Materials, Engineering and Applications”., J. Wiley and Sons, N.Y., 2020

Contributions, regarding the topics listed at the start of this document, are invited for this Special Issue “Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein”.

Prof. Dr. Yiquan Wu
Guest Editor

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Published Papers (7 papers)

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Research

13 pages, 9458 KiB  
Article
Optimization of Yb:CaF2 Transparent Ceramics by Air Pre-Sintering and Hot Isostatic Pressing
by Xiang Li, Chen Hu, Lihao Guo, Junlin Wu, Guido Toci, Angela Pirri, Barbara Patrizi, Matteo Vannini, Qiang Liu, Dariusz Hreniak and Jiang Li
Ceramics 2024, 7(3), 1053-1065; https://doi.org/10.3390/ceramics7030069 - 15 Aug 2024
Cited by 1 | Viewed by 830
Abstract
Yb:CaF2 transparent ceramics represent a promising laser gain medium for ultra-short lasers due to their characteristics: low phonon energy, relatively high thermal conductivity, negative thermo-optical coefficient, and low refractive index. Compared to single crystals, Yb:CaF2 ceramics offer superior mechanical properties, lower [...] Read more.
Yb:CaF2 transparent ceramics represent a promising laser gain medium for ultra-short lasers due to their characteristics: low phonon energy, relatively high thermal conductivity, negative thermo-optical coefficient, and low refractive index. Compared to single crystals, Yb:CaF2 ceramics offer superior mechanical properties, lower cost, and it is easier to obtain large-sized samples with proper shape and uniform Yb3+ doping at high concentrations. The combination of air pre-sintering and Hot Isostatic Pressing (HIP) emerges as a viable strategy for achieving high optical quality and fine-grained structure of ceramics at lower sintering temperatures. The properties of the powders used in ceramic fabrication critically influence both optical quality and laser performance of Yb:CaF2 ceramics. In this study, the 5 atomic percentage (at.%) Yb:CaF2 transparent ceramics were fabricated by air pre-sintering and hot isostatic pressing (HIP) using nano-powders synthesized through the co-precipitation method. The co-precipitated powders were optimized by studying air calcination temperature (from 350 to 550 °C). The influence of calcination temperature on the microstructure and laser performance of Yb:CaF2 ceramics was studied in detail. The 5 at.% Yb:CaF2 transparent ceramics air pre-sintered at 625 °C from powders air calcined at 400 °C and HIP post-treated at 600 °C exhibited the highest in-line transmittance of 91.5% at 1200 nm (3.0 mm thickness) and the best laser performance. Specifically, a maximum output power of 0.47 W with a maximum slope efficiency of 9.2% at 1029 nm under quasi-CW (QCW) pumping was measured. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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16 pages, 3660 KiB  
Article
Improving the Transparency of a MgAl2O4 Spinel Damaged by Sandblasting through a SiO2-ZrO2 Coating
by Akram Zegadi, Abdelwahhab Ayadi, Ikram Khellaf, Mohamed Hamidouche, Gilbert Fantozzi, Alicia Durán and Yolanda Castro
Ceramics 2024, 7(2), 743-758; https://doi.org/10.3390/ceramics7020049 - 28 May 2024
Viewed by 926
Abstract
Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact [...] Read more.
Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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18 pages, 4897 KiB  
Article
Enhancing Transparency in Non-Cubic Calcium Phosphate Ceramics: Effect of Starting Powder, LiF Doping, and Spark Plasma Sintering Parameters
by Kacper Albin Prokop, Sandrine Cottrino, Vincent Garnier, Gilbert Fantozzi, Yannick Guyot, Georges Boulon and Małgorzata Guzik
Ceramics 2024, 7(2), 607-624; https://doi.org/10.3390/ceramics7020040 - 30 Apr 2024
Viewed by 1325
Abstract
Our objective is to achieve a new good-quality and mechanically durable high-transparency material that, when activated by rare earth ions, can be used as laser sources, scintillators, or phosphors. The best functional transparent ceramics are formed from high-symmetry systems, mainly cubic. Considering hexagonal [...] Read more.
Our objective is to achieve a new good-quality and mechanically durable high-transparency material that, when activated by rare earth ions, can be used as laser sources, scintillators, or phosphors. The best functional transparent ceramics are formed from high-symmetry systems, mainly cubic. Considering hexagonal hydroxyapatite, which shows anisotropy, the particle size of the initial powder is extremely important and should be of the order of several tens of nanometers. In this work, transparent micro-crystalline ceramics of non-cubic Ca10(PO4)6(OH)2 calcium phosphate were fabricated via Spark Plasma Sintering (SPS) from two types of nanopowders i.e., commercially available (COM. HA) and laboratory-made (LAB. HA) via the hydrothermal (HT) protocol. Our study centered on examining how the quality of sintered bodies is affected by the following parameters: the addition of LiF sintering agent, the temperature during the SPS process, and the quality of the starting nanopowders. The phase purity, microstructure, and optical transmittance of the ceramics were investigated to determine suitable sintering conditions. The best optical ceramics were obtained from LAB. HA nanopowder with the addition of 0.25 wt.% of LiF sintered at 1000 °C and 1050 °C. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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10 pages, 4804 KiB  
Article
Beyond Scanning Electron Microscopy: Comprehensive Pore Analysis in Transparent Ceramics Using Optical Microscopy
by Francesco Picelli, Jan Hostaša, Andreana Piancastelli, Valentina Biasini, Cesare Melandri and Laura Esposito
Ceramics 2024, 7(1), 401-410; https://doi.org/10.3390/ceramics7010025 - 15 Mar 2024
Viewed by 1674
Abstract
Developing an effective method of quantifying defects in the bulk of transparent ceramics is a challenging task that could facilitate their widespread use as a substitute for single crystals. Conventionally, SEM analysis is used to examine the microstructure but it is limited to [...] Read more.
Developing an effective method of quantifying defects in the bulk of transparent ceramics is a challenging task that could facilitate their widespread use as a substitute for single crystals. Conventionally, SEM analysis is used to examine the microstructure but it is limited to the material surface. On the other hand, optical transmittance assesses material quality, but does not provide information on the size and concentration of defects. In this study, we illustrate the use of a digital optical microscope for the non-destructive, precise, and rapid analysis of residual porosity in transparent ceramics. YAG-based ceramics doped with Yb have been selected for this study because they are used as laser gain media, an application that requires virtually defect-free components. Different production processes were used to produce YAG samples, and the digital optical microscope analysis was used to compare them. This analysis was shown to be effective and precise to measure the size and concentration of the residual pores. In addition, the comparison of samples obtained with different production processes showed that the size and distribution of the residual porosity is affected by the drying step of the powders before shaping by pressing, as well as by the sintering aids used to ease the densification. It also showed that the transmittance is influenced by both the total volume and the concentration of the pores. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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14 pages, 6981 KiB  
Article
Optical and Spectroscopic Properties of Ho:Lu2O3 Transparent Ceramics Elaborated by Spark Plasma Sintering
by Lucas Viers, Simon Guené-Girard, Gilles Dalla-Barba, Véronique Jubéra, Éric Cormier, Rémy Boulesteix and Alexandre Maître
Ceramics 2024, 7(1), 208-221; https://doi.org/10.3390/ceramics7010013 - 8 Feb 2024
Viewed by 1645
Abstract
In this work, transparent ceramics were manufactured from nanopowders synthesized by aqueous coprecipitation followed by Spark Plasma Sintering (SPS) to ensure rapid and full densification. The photoluminescence of Ho:Lu2O3 transparent ceramics was studied in the Visible and IR domains as [...] Read more.
In this work, transparent ceramics were manufactured from nanopowders synthesized by aqueous coprecipitation followed by Spark Plasma Sintering (SPS) to ensure rapid and full densification. The photoluminescence of Ho:Lu2O3 transparent ceramics was studied in the Visible and IR domains as a function of Ho3+ dopant level from 0.5 at.% to 10 at.%. A cross-relaxation mechanism was identified and favors the 2 μm emission. All of the obtained results indicate that the optical properties are very similar between Lu2−xHoxO3 transparent ceramics and single crystals. Thus, the SPS technique appears to be a very promising method to manufacture such ceramics, which could be used as amplifier media for high-energy solid-state lasers. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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14 pages, 10423 KiB  
Article
Glass Composition for Coating and Bonding of Polycrystalline Spinel Ceramic Substrates
by Jacob Hormadaly
Ceramics 2024, 7(1), 101-114; https://doi.org/10.3390/ceramics7010008 - 25 Jan 2024
Cited by 1 | Viewed by 1855
Abstract
Design considerations of the lead-based glass composition was broadened beyond the two known criteria of matched index of refraction and thermal coefficient of expansion to include previous studies of thick film materials. Five criteria for the glass-design composition were used: matched index of [...] Read more.
Design considerations of the lead-based glass composition was broadened beyond the two known criteria of matched index of refraction and thermal coefficient of expansion to include previous studies of thick film materials. Five criteria for the glass-design composition were used: matched index of refraction and thermal coefficient of expansion, components (MgO and Al2O3) to slow down dissolution of spinel (MgAl2O4) into the glass, non-crystallizing glass in a broad temperature range and glass with good chemical durability. Synthesis and characterization of glass, glass paste preparation and its application to spinel substrates to form coating and bonding and optical characterizations in the UV, VIS and IR of coated, uncoated, and bonded spinel substrates of two commercial sources are described. Enhancement of transmittance exceeding the theoretical value of polished spinel was found for the first time when glass coating was applied to a ground face of semi-polished spinel. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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19 pages, 84491 KiB  
Article
Mechanical Behavior of Transparent Spinel Fabricated by Spark Plasma Sintering
by Khadidja Hoggas, Salim Benaissa, Abdelbaki Cherouana, Sofiane Bouheroum, Abdenacer Assali, Mohamed Hamidouche and Gilbert Fantozzi
Ceramics 2023, 6(2), 1191-1209; https://doi.org/10.3390/ceramics6020072 - 31 May 2023
Cited by 2 | Viewed by 1973
Abstract
In this work, a transparent nanostructured ceramic magnesium aluminate spinel (MgAl2O4) was fabricated by Spark Plasma Sintering (SPS) from commercial spinel nano-powders at different temperatures (1300, 1350 and 1400 °C). The sintered samples were thoroughly examined to assess their [...] Read more.
In this work, a transparent nanostructured ceramic magnesium aluminate spinel (MgAl2O4) was fabricated by Spark Plasma Sintering (SPS) from commercial spinel nano-powders at different temperatures (1300, 1350 and 1400 °C). The sintered samples were thoroughly examined to assess their microstructural, optical, and mechanical properties. Various techniques such as SEM, AFM, spectrophotometer with an integrating sphere, instrumented Vickers indenter, Pin-on-Disk tribometer, scratch tester, and sandblasting device were employed to characterize the sintered samples. The results indicated the significant impact of the sintering temperature on the properties of the spinel samples. Particularly, the samples sintered at T = 1350 °C exhibited the highest Real In-line Transmission (RIT = 72% at 550 nm and 80% at 1000 nm). These samples demonstrated the highest hardness value (HV = 16.7 GPa) compared to those sintered at 1300 °C (HV = 15.6 GPa) and 1400 °C (HV = 15.1 GPa). The measured fracture toughness of the sintered samples increased substantially with increasing sintering temperature. Similarly, the tribological study revealed that the friction coefficient of the sintered spinel samples increased with the sintering temperature, and the spinel sintered at 1350 °C exhibited the lowest wear rate. Additionally, sandblasting and scratch tests confirmed the significant influence of the sintering temperature on the mechanical properties of the fabricated spinels. Overall, the spinel sintered at 1350 °C presented the best compromise in terms of all the evaluated properties. Full article
(This article belongs to the Special Issue Transparent Ceramics—a Theme Issue in Honor of Dr. Adrian Goldstein)
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