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15 pages, 6199 KiB

Open AccessArticle

Porous Lithium Disilicate Glass–Ceramics Prepared by Cold Sintering Process Associated with Post-Annealing Technique

by Xigeng Lyu, Yeongjun Seo, Do Hyung Han, Sunghun Cho, Yoshifumi Kondo, Tomoyo Goto and Tohru Sekino

Materials 2024, 17(2), 381; https://doi.org/10.3390/ma17020381 - 12 Jan 2024

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Abstract

Using melt-derived LD glass powders and 5–20 M NaOH solutions, porous lithium disilicate (Li₂Si₂O₅, LD) glass–ceramics were prepared by the cold sintering process (CSP) associated with the post-annealing technique. In this novel technique, H₂O vapor [...] Read more.

Using melt-derived LD glass powders and 5–20 M NaOH solutions, porous lithium disilicate (Li₂Si₂O₅, LD) glass–ceramics were prepared by the cold sintering process (CSP) associated with the post-annealing technique. In this novel technique, H₂O vapor originating from condensation reactions between residual Si–OH groups in cold-sintered LD glasses played the role of a foaming agent. With the increasing concentration of NaOH solutions, many more residual Si–OH groups appeared, and then rising trends in number as well as size were found for spherical pores formed in the resultant porous LD glass–ceramics. Correspondingly, the total porosities and average pore sizes varied from 25.6 ± 1.3% to 48.6 ± 1.9% and from 1.89 ± 0.68 μm to 13.40 ± 10.27 μm, respectively. Meanwhile, both the volume fractions and average aspect ratios of precipitated LD crystals within their pore walls presented progressively increasing tendencies, ranging from 55.75% to 76.85% and from 4.18 to 6.53, respectively. Young’s modulus and the hardness of pore walls for resultant porous LD glass–ceramics presented remarkable enhancement from 56.9 ± 2.5 GPa to 79.1 ± 2.1 GPa and from 4.6 ± 0.9 GPa to 8.1 ± 0.8 GPa, whereas their biaxial flexural strengths dropped from 152.0 ± 6.8 MPa to 77.4 ± 5.4 MPa. Using H₂O vapor as a foaming agent, this work reveals that CSP associated with the post-annealing technique is a feasible and eco-friendly methodology by which to prepare porous glass–ceramics. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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12 pages, 2865 KiB

Open AccessArticle

Effect of P₂O₅ and Na₂O on the Solubility of Molybdenum and Structural Features in Borosilicate Glass

by Hao Liu, Yongchang Zhu, Jichuan Huo, Zhu Cui, Xingquan Zhang, Qin Jiang, Debo Yang and Baojian Meng

Materials 2022, 15(15), 5464; https://doi.org/10.3390/ma15155464 - 08 Aug 2022

Cited by 2 | Viewed by 1580

Abstract

In this paper, the effect of doping phosphorus in a borosilicate glass matrix to improve the solubility of Mo was investigated by X-ray diffraction (XRD), Raman, and solid-state nuclear magnetic resonance (NMR) spectroscopy, and the effectiveness of Na content on P species inhibiting [...] Read more.

In this paper, the effect of doping phosphorus in a borosilicate glass matrix to improve the solubility of Mo was investigated by X-ray diffraction (XRD), Raman, and solid-state nuclear magnetic resonance (NMR) spectroscopy, and the effectiveness of Na content on P species inhibiting the growth of the crystallization of Mo was assessed. The results indicate that phosphate-doped borosilicate glass can host 4 mol% of Mo, and that such a borosilicate glass matrix could only accommodate 1 mol% of Mo without phosphate doping. The effectiveness of phosphorus may be correlated with the Na content in borosilicate glass, and a high Na content borosilicate glass matrix requires more P doping to accommodate Mo. In addition, incorporating large amounts of P can compromise the aqueous durability of the glass matrix. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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12 pages, 4684 KiB

Open AccessArticle

Divalent Yb-Doped Silica Glass and Fiber with High Quantum Efficiency for White Light Source

by Changming Xia, Jiantao Liu, Zhiyun Hou and Guiyao Zhou

Materials 2022, 15(9), 3148; https://doi.org/10.3390/ma15093148 - 26 Apr 2022

Cited by 1 | Viewed by 1823

Abstract

The 4f¹³5d–4f¹⁴ energy transition of Yb²⁺ ions can cover the whole white light wavelength, Yb²⁺-doped materials have thus been a hot research field. In order to obtain a white light source, many kinds of Yb²⁺-doped [...] Read more.

The 4f¹³5d–4f¹⁴ energy transition of Yb²⁺ ions can cover the whole white light wavelength, Yb²⁺-doped materials have thus been a hot research field. In order to obtain a white light source, many kinds of Yb²⁺-doped materials have been prepared. In this study, divalent Yb²⁺-doped silica fiber was fabricated using rod-in-tube technology. The fiber core of Yb²⁺-doped silica glass was prepared with high-temperature melting technology under vacuum conditions. The spectroscopic properties of the Yb²⁺-doped glass and fiber were studied. The experiments indicate that divalent Yb²⁺-doped glass has a high quantum efficiency and super-broadband fluorescence in the visible region with an excitation wavelength of 405 nm. In addition, the results suggest that Yb²⁺-doped fiber has a potential for application in visible fiber lasers and fiber amplification. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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15 pages, 3507 KiB

Open AccessArticle

Role of Eu²⁺ and Dy³⁺ Concentration in the Persistent Luminescence of Sr₂MgSi₂O₇ Glass-Ceramics

by Laura Fernández-Rodríguez, Rolindes Balda, Joaquín Fernández, Alicia Durán and María Jesús Pascual

Materials 2022, 15(9), 3068; https://doi.org/10.3390/ma15093068 - 23 Apr 2022

Cited by 4 | Viewed by 2124

Abstract

In this study, glass-ceramics based on Sr₂MgSi₂O₇ phosphor co-doped with Eu/Dy were obtained from the sintering and crystallisation of glass powders. The glasses were melted in a gas furnace to simulate an industrial process, and the dopant concentration [...] Read more.

In this study, glass-ceramics based on Sr₂MgSi₂O₇ phosphor co-doped with Eu/Dy were obtained from the sintering and crystallisation of glass powders. The glasses were melted in a gas furnace to simulate an industrial process, and the dopant concentration was varied to optimise the luminescence persistence times. The doped parent glasses showed red emission under UV light excitation due to the doping of Eu³⁺ ions, while the corresponding glass-ceramics showed persistent blue emission corresponding to the presence of Eu²⁺ in the crystalline environment. The dopant concentration had a strong impact on the sintering/crystallisation kinetics affecting the final glass-ceramic microstructure. The microstructures and morphology of the crystals responsible for the blue emission were observed by scanning electron microscopy–cathodoluminescence. The composition of the crystallised phases and the distribution of rare-earth (RE) ions in the crystals and in the residual glassy phase were determined by X-ray diffraction and energy dispersive X-ray analysis. The emission and persistence of phosphorescence were studied by photoluminescence. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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7 pages, 1417 KiB

Open AccessArticle

Net Optical Gain Coefficients of Cu⁺ and Tm³⁺ Single-Doped and Co-Doped Germanate Glasses

by Yuhang Zhang, Baojiu Chen, Xizhen Zhang, Jinsu Zhang, Sai Xu, Xiangping Li, Yichao Wang, Yongze Cao, Lei Li, Hongquan Yu, Xin Wang, Duan Gao, Xuzhu Sha and Li Wang

Materials 2022, 15(6), 2134; https://doi.org/10.3390/ma15062134 - 14 Mar 2022

Cited by 3 | Viewed by 1695

Abstract

Broadband tunable solid-state lasers continue to present challenges to scientists today. The gain medium is significant for realizing broadband tunable solid-state lasers. In this investigation, the optical gain performance for Tm³⁺ and Cu⁺ single-doped and co-doped germanate glasses with broadband emissions [...] Read more.

Broadband tunable solid-state lasers continue to present challenges to scientists today. The gain medium is significant for realizing broadband tunable solid-state lasers. In this investigation, the optical gain performance for Tm³⁺ and Cu⁺ single-doped and co-doped germanate glasses with broadband emissions was studied via an amplified spontaneous emission (ASE) technique. It was found that the net optical gain coefficients (NOGCs) of Tm³⁺ single-doped glass were larger than those for Cu⁺ single-doped glass. When Tm³⁺ was introduced, the emission broadband width of Cu⁺-doped glass was effectively extended. Moreover, it was found that for the co-doped glass the NOGCs at the wavelengths for Tm³⁺ and Cu⁺ emissions were larger than those of Tm³⁺ and Cu⁺ single-doped glasses at the same wavelengths. In addition, the NOGC values of Tm³⁺ and Cu⁺ co-doped germanate glasses were of the same order of magnitude, and were maintained in a stable range at different wavelengths. These results indicate that the Tm³⁺ and Cu⁺ co-doped glasses studied may be a good candidate medium for broadband tunable solid-state lasers. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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11 pages, 2441 KiB

Open AccessArticle

Effect of Glass Composition on Luminescence and Structure of CsPbBr₃ Quantum Dots in an Amorphous Matrix

by Ruilin Zheng, Jumpei Ueda, Kenji Shinozaki and Setsuhisa Tanabe

Materials 2022, 15(5), 1678; https://doi.org/10.3390/ma15051678 - 23 Feb 2022

Cited by 4 | Viewed by 2328

Abstract

Glass matrix embedding is an efficient way to improve the chemical and thermal stability of the halide perovskite QDs. However, CsPbX₃ QDs exhibit distinct optical properties in different glass matrixes, including photoluminescence (PL) peak position, PL peak width, and optical band gap. [...] Read more.

Glass matrix embedding is an efficient way to improve the chemical and thermal stability of the halide perovskite QDs. However, CsPbX₃ QDs exhibit distinct optical properties in different glass matrixes, including photoluminescence (PL) peak position, PL peak width, and optical band gap. In this work, the temperature-dependent PL spectra, absorption spectra, high-energy X-ray structure factor S(Q), and pair distribution function (PDF) were integrated to analyze the structural evolution of CsPbBr₃ QDs in different glass matrixes. The results show that the lattice parameters and atomic spacing of CsPbBr₃ QDs are affected by the glass composition in which they are embedded. The most possibility can be attributed to the thermal expansion mismatch between CsPbBr₃ QDs and the glass matrix. The results may provide a new way to understand the effect of the glass composition on the optical properties of CsPbBr₃ QDs in a glass matrix. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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17 pages, 4950 KiB

Open AccessArticle

Early-Stage Dissolution Kinetics of Silicate-Based Bioactive Glass under Dynamic Conditions: Critical Evaluation

by Dagmar Galusková, Hana Kaňková, Anna Švančárková and Dušan Galusek

Materials 2021, 14(12), 3384; https://doi.org/10.3390/ma14123384 - 18 Jun 2021

Cited by 7 | Viewed by 2234

Abstract

This manuscript presents a systematic and detailed study of ion release from 45S5 bioactive glass to develop a methodology to directly monitor dissolved ions in a simulated fluid via inductively coupled plasma optical emission spectrometry (ICP OES). For the kinetic study, two dynamic [...] Read more.

This manuscript presents a systematic and detailed study of ion release from 45S5 bioactive glass to develop a methodology to directly monitor dissolved ions in a simulated fluid via inductively coupled plasma optical emission spectrometry (ICP OES). For the kinetic study, two dynamic tests, an inline ICP test and a flow-through test, are performed with the same flow rate, temperature, pH, ionic strength of the solution, and sample surface to leaching solution volume ratio. The flow-through test allows for the measurement of an initial dissolution rate, as well the maximum amount of any species released from the surface of the glass. In addition, the data from the inline ICP test are obtained by immediate and direct monitoring of ions from the first minutes of contact of the glass with aqueous fluids with pH values of 4 and 7.4. The overall dissolution rates of the tested commercial bioactive glass in simulated body fluid (SBF) (pH 7.4) were significantly lower compared to the initial rate acquired. The methodology developed in this study can be applied to monitor the controlled release of ions with additional therapeutic functionalities, where the amount of ions released in the first minutes can be critical for the resulting biological performance. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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7 pages, 928 KiB

Open AccessArticle

Quantification of Carbonic Contamination of Fused Silica Surfaces at Different Stages of Classical Optics Manufacturing

by Robert Köhler, Domenico Hellrung, Daniel Tasche and Christoph Gerhard

Materials 2021, 14(7), 1620; https://doi.org/10.3390/ma14071620 - 26 Mar 2021

Cited by 3 | Viewed by 1681

Abstract

The chemical composition of ground and polished fused silica glass surfaces plays a decisive role in different applications of optics. In particular, a high level of carbon impurities is often undesirable for further processing and especially for gluing or cementing where adhesion failure [...] Read more.

The chemical composition of ground and polished fused silica glass surfaces plays a decisive role in different applications of optics. In particular, a high level of carbon impurities is often undesirable for further processing and especially for gluing or cementing where adhesion failure may be attributed to carbonic surface-adherent contaminants. In this study, the surface carbon content at different stages of classical optics manufacturing was thus investigated. Two different standard processes—grinding and lapping with two final polishing processes using both polyurethane and pitch pads—were considered. After each process step, the chemical composition and roughness of the surface were analysed using X-ray photoelectron spectroscopy and atomic force microscopy. An obvious correlation between surface roughness and effective surface area, respectively, and the proportion of carbon contamination was observed. The lowest carbon contamination was found in case of lapped and pitch polished surfaces. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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Review

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22 pages, 8107 KiB

Open AccessEditor’s ChoiceReview

Sol–Gel Photonic Glasses: From Material to Application

by Giancarlo C. Righini, Cristina Armellini, Maurizio Ferrari, Alice Carlotto, Alessandro Carpentiero, Andrea Chiappini, Alessandro Chiasera, Anna Lukowiak, Thi Ngoc Lam Tran and Stefano Varas

Materials 2023, 16(7), 2724; https://doi.org/10.3390/ma16072724 - 29 Mar 2023

Cited by 3 | Viewed by 1966

Abstract

In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention [...] Read more.

In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention is devoted to silicate glasses of different compositions, which are characterized by specific optical and spectroscopic properties for various applications, ranging from luminescent systems to light-confining structures and memristors. In particular, the roles of rare-earth doping, matrix composition, the densification process and the fabrication protocol on the structural, optical and spectroscopic properties of the developed photonic systems are discussed through appropriate examples. Some achievements in the fabrication of oxide sol–gel optical waveguides and of micro- and nanostructures for the confinement of light are also briefly discussed. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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