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Special Issue "Transparent Ceramics and Applications"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 August 2018

Special Issue Editor

Guest Editor
Dr. Rémy Boulesteix

University of Limoges; Limoges, France
Website | E-Mail
Interests: transparent ceramics; ceramic processing; manufacturing of functionally graded materials for new/optimized optical devices; optical properties; laser applications

Special Issue Information

Dear Colleagues,

Transparent bulk ceramics constitute one of the latest developments in the general field of technical ceramics. The past 50 years have shown strong evolution and innovation in this research area.

Transparent ceramics combine the transparency abilities of classical windows, made from others materials (inorganic glasses, polymers, single-crystals), with the specific functional properties of polycristalline ceramics. This makes them attractive for applications in various domains. Most of manufactured transparent ceramics for industry are simple, bulk transparent parts, whereas some others are highly sophisticated, with complex shapes and/or architectures (composition gradient). Examples include optically-passive, such as transparent armor, infrared windows, optical lenses, artificial gems, and transparent parts for jewelry, or optically-active devices, such as scintillators, amplifiers, or Q-switch media for laser systems.

With their need for full densification, each step of the manufacturing process must be controlled perfectly. For this purpose, many advances were made in various scientific and technological fields, such as powder synthesis, shaping, and sintering. Non-exhaustively, the synthesis of nanoparticles using soft chemistry, green compact shaping, using either solid methods (Cold Isostatic Pressing) or liquid methods (casting of suspensions), and sintering using pressure-less or pressure-assisted techniques (Hot Pressing, Spark Plasma Sintering, Hot Isostatic Pressing, etc.) have been proven to be suitable for obtaining transparent ceramics. Whatever the manufacturing process, the global goals are to ensure a high purity with limited contamination, and to promote particle/grain and pore size homogeneity.

One of the most emblematic transparent ceramic material in the two past decades Yttrium-Aluminum Garnet (YAG)-based transparent ceramics, has revolutionized laser technology: it is now possible to manufacture large pieces of tens centimeters with high doping levels and complex architectures (pieces with composition gradient—also called composites); as opposed to single-crystal technology. Recently, powerful lasers, operating at up to 100 kW, have been demonstrated to be feasible. There are many other transparent ceramics and applications, indicating the great potential of this research area.

It is my pleasure to invite you to submit a manuscript for this Special Issue. Original research, in the form of full papers, short communications, and reviews, are all welcome.

Dr. Rémy Boulesteix
Guest Editor

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. Materials 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 1600 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

  • Transparent ceramics

  • Garnet, Spinel, Alumina, non-oxide TCs

  • Ceramic processing: powder synthesis, shaping and sintering

  • Optical properties and applications

Published Papers (3 papers)

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Research

Open AccessArticle A Comprehensive Characterization of a 10 at.% Yb:YSAG Laser Ceramic Sample
Materials 2018, 11(5), 837; https://doi.org/10.3390/ma11050837
Received: 5 April 2018 / Revised: 26 April 2018 / Accepted: 11 May 2018 / Published: 18 May 2018
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Abstract
We report a comprehensive characterization of a 10 at.% Yb3+-doped YSAG (Yb:Y3ScxAl(5−x)O12, x = 1.5) ceramic, including microstructural, spectroscopic and laser properties. Moreover, we illustrate and discuss the fabrication technique. Yb3+ in
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We report a comprehensive characterization of a 10 at.% Yb3+-doped YSAG (Yb:Y3ScxAl(5−x)O12, x = 1.5) ceramic, including microstructural, spectroscopic and laser properties. Moreover, we illustrate and discuss the fabrication technique. Yb3+ in YSAG features a broader absorption and emission band than in traditional YAG, which is advantageous for laser applications (i.e., tunable laser sources, ultrafast pulse generation). Pumping in a quasi continuous wave regime at 936 nm, the ceramic has shown good laser performance as the maximum output power was 6.3 W with a corresponding slope efficiency (ηs) of 67.8%. In continuous wave regime instead, the maximum output power was 5 W with ηs = 52.7%. The laser emission wavelengths in free running were λL = 1051 nm and λL = 1031 nm, depending on the output coupler transmission. Finally, by a tunable cavity we obtained laser emission spanning from 991.5 to 1073 nm, i.e., 81.5 nm, which is the broadest tuning range ever reported for this material, to the best of our knowledge. Full article
(This article belongs to the Special Issue Transparent Ceramics and Applications)
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Open AccessFeature PaperArticle Composite Laser Ceramics by Advanced Bonding Technology
Materials 2018, 11(2), 271; https://doi.org/10.3390/ma11020271
Received: 11 January 2018 / Revised: 5 February 2018 / Accepted: 5 February 2018 / Published: 9 February 2018
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Abstract
Composites obtained by bonding materials with the same crystal structure and different chemical compositions can create new functions that do not exist in conventional concepts. We have succeeded in bonding polycrystalline YAG and Nd:YAG ceramics without any interstices at the bonding interface, and
[...] Read more.
Composites obtained by bonding materials with the same crystal structure and different chemical compositions can create new functions that do not exist in conventional concepts. We have succeeded in bonding polycrystalline YAG and Nd:YAG ceramics without any interstices at the bonding interface, and the bonding state of this composite was at the atomic level, similar to the grain boundary structure in ceramics. The mechanical strength of the bonded composite reached 278 MPa, which was not less than the strength of each host material (269 and 255 MPa). Thermal conductivity of the composite was 12.3 W/mK (theoretical value) which is intermediate between the thermal conductivities of YAG and Nd:YAG (14.1 and 10.2 W/mK, respectively). Light scattering cannot be detected at the bonding interface of the ceramic composite by laser tomography. Since the scattering coefficients of the monolithic material and the composite material formed by bonding up to 15 layers of the same materials were both 0.10%/cm, there was no occurrence of light scattering due to the bonding. In addition, it was not detected that the optical distortion and non-uniformity of the refractive index variation were caused by the bonding. An excitation light source (LD = 808 nm) was collimated to 200 μm and irradiated into a commercial 1% Nd:YAG single crystal, but fracture damage occurred at a low damage threshold of 80 kW/cm2. On the other hand, the same test was conducted on the bonded interface of 1% Nd:YAG-YAG composite ceramics fabricated in this study, but it was not damaged until the excitation density reached 127 kW/cm2. 0.6% Nd:YAG-YAG composite ceramics showed high damage resistance (up to 223 kW/cm2). It was concluded that composites formed by bonding polycrystalline ceramics are ideal in terms of thermo-mechanical and optical properties. Full article
(This article belongs to the Special Issue Transparent Ceramics and Applications)
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Open AccessArticle Variation of Structure and Photoluminescence Properties of Ce3+ Doped MgAlON Transparent Ceramics with Different Doping Content
Materials 2017, 10(7), 792; https://doi.org/10.3390/ma10070792
Received: 23 May 2017 / Revised: 18 June 2017 / Accepted: 5 July 2017 / Published: 13 July 2017
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Abstract
Transparent MgAlON:Ce fluorescent ceramics with doping content of 0.005, 0.01, and 0.02 at % were fabricated by pressureless sintering. All the samples were dense and large in grain size. Under the excitation of 320 nm UV, the samples emitted blue lights centered around
[...] Read more.
Transparent MgAlON:Ce fluorescent ceramics with doping content of 0.005, 0.01, and 0.02 at % were fabricated by pressureless sintering. All the samples were dense and large in grain size. Under the excitation of 320 nm UV, the samples emitted blue lights centered around 410 nm. The 0.005 and 0.01 at % Ce3+ doped samples were single phase by XRD detection, and possessed good optical and mechanical properties, and luminous thermal stability. The fluorescence lifetime, the CL and PL spectra analysis, indicated that most of the luminous centers were segregated in GB, and there was still a small part of second phase existing in 0.01 at % Ce3+ doped sample, which revealed that spectroscopy methods possessed better sensitivity in smaller scale and lower concentration detection than XRD. As the doping content increasing to 0.02 at %, a mass of second phase arose, which resulted in the optical transparency, mechanical property, luminous thermal stability decline, and the PL spectra red shift by the formation of second phase. It revealed that the performances were fatally deteriorated by excess doping of Ce3+ ions. Full article
(This article belongs to the Special Issue Transparent Ceramics and Applications)
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