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Keywords = nano-crystallized glass ceramic

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11 pages, 2797 KiB  
Article
Controllable Nano-Crystallization in Fluoroborosilicate Glass Ceramics for Broadband Visible Photoluminescence
by Yuanhang Xiang, Yi Long, Peiying Cen, Sirang Liu, Zaijin Fang and Renjie Jiao
Nanomaterials 2025, 15(2), 144; https://doi.org/10.3390/nano15020144 - 20 Jan 2025
Viewed by 1026
Abstract
A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B2O3 into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 [...] Read more.
A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B2O3 into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 °C, and the abnormal crystallization in the fabrication process of fluorosilicate glass was avoided. More importantly, the controlled crystallizations of KZnF3 and KYb3F10 in fluoroborosilicate glass ceramics enhanced the emission of Mn2+ and Mn2+–Yb3+ dimers by 6.7 and 54 times, respectively. Moreover, the upconversion emission color of glass ceramic could be modulated from yellow to white and blue by adjusting the Yb3+ concentration. The well-designed glass ceramic is a novel and significant compound to simultaneously provide efficiently coordinated sites for transition metal and rare earth ions. More importantly, the design strategy opens a new way for engineering high-quality oxy-fluoride glass ceramics with properties of excellent stability, controllable nano-crystallization and high-efficiency photoluminescence. Full article
(This article belongs to the Section Nanocomposite Materials)
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13 pages, 5031 KiB  
Article
Stabilization of δ-like Bi2O3 Phase at Room Temperature in Binary and Ternary Bismuthate Glass Systems with Al2O3, SiO2, GeO2, and B2O3
by Viktoriia Vlasenko, Maciej Nowagiel, Marek Wasiucionek and Tomasz K. Pietrzak
Materials 2024, 17(16), 4023; https://doi.org/10.3390/ma17164023 - 13 Aug 2024
Cited by 4 | Viewed by 1785
Abstract
Recently, it was shown that the nanocrystallization of Bi2O3 glasses with the addition of SiO2 and Al2O3 leads to the stabilization of the δ-like Bi2O3 phase at [...] Read more.
Recently, it was shown that the nanocrystallization of Bi2O3 glasses with the addition of SiO2 and Al2O3 leads to the stabilization of the δ-like Bi2O3 phase at least down to room temperature, which is significantly below its stability range in bulk form. In this research, we investigated the properties of bismuthate glasses synthesized with various glass-forming agents such as SiO2, GeO2, B2O3, and Al2O3. It was demonstrated that vitrification of all these systems is possible using a standard melt quenching route. Furthermore, we investigated the crystallization processes in pristine glasses upon increasing the temperature and the thermal stability of arising phases using thermal analysis and high-temperature XRD in situ experiments. It was shown that it is possible to stabilize crystallites’ isostructures with δ-Bi2O3 embedded in a residual glassy matrix down to room temperature. The temperature range of the appearance of the δ-like phase strongly depended on the nominal composition of the glasses. We postulate that the confinement effect depends on the local properties of the residual glassy matrix and its ability to introduce sufficient force to stretch the structure of the δ-like Bi2O3 phase in the nanocrystallites. Full article
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23 pages, 7794 KiB  
Article
Effect of Water-Soluble Polymers on the Rheology and Microstructure of Polymer-Modified Geopolymer Glass-Ceramics
by John M. Migliore, Patrick Hewitt, Theo J. Dingemans, Davide L. Simone and William Jacob Monzel
Materials 2024, 17(12), 2856; https://doi.org/10.3390/ma17122856 - 11 Jun 2024
Cited by 1 | Viewed by 1851
Abstract
This work explores the effects of rigid (0.1, 0.25, and 0.5 wt. %) and semi-flexible (0.5, 1.0, and 2.5 wt. %) all-aromatic polyelectrolyte reinforcements as rheological and morphological modifiers for preparing phosphate geopolymer glass–ceramic composites. Polymer-modified aluminosilicate–phosphate geopolymer resins were prepared by high-shear [...] Read more.
This work explores the effects of rigid (0.1, 0.25, and 0.5 wt. %) and semi-flexible (0.5, 1.0, and 2.5 wt. %) all-aromatic polyelectrolyte reinforcements as rheological and morphological modifiers for preparing phosphate geopolymer glass–ceramic composites. Polymer-modified aluminosilicate–phosphate geopolymer resins were prepared by high-shear mixing of a metakaolin powder with 9M phosphoric acid and two all-aromatic, sulfonated polyamides. Polymer loadings between 0.5–2.5 wt. % exhibited gel-like behavior and an increase in the modulus of the geopolymer resin as a function of polymer concentration. The incorporation of a 0.5 wt. % rigid polymer resulted in a three-fold increase in viscosity relative to the control phosphate geopolymer resin. Hardening, dehydration, and crystallization of the geopolymer resins to glass-ceramics was achieved through mold casting, curing at 80 °C for 24 h, and a final heat treatment up to 260 °C. Scanning electron microscopy revealed a decrease in microstructure porosity in the range of 0.78 μm to 0.31 μm for geopolymer plaques containing loadings of 0.5 wt. % rigid polymer. Nano-porosity values of the composites were measured between 10–40 nm using nitrogen adsorption (Brunauer–Emmett–Teller method) and transmission electron microscopy. Nanoindentation studies revealed geopolymer composites with Young’s modulus values of 15–24 GPa and hardness values of 1–2 GPa, suggesting an increase in modulus and hardness with polymer incorporation. Additional structural and chemical analyses were performed via thermal gravimetric analysis, Fourier transform infrared radiation, X-ray diffraction, and energy dispersive spectroscopy. This work provides a fundamental understanding of the processing, microstructure, and mechanical behavior of water-soluble, high-performance polyelectrolyte-reinforced geopolymer composites. Full article
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14 pages, 6709 KiB  
Article
Glass-Ceramic Fillers Based on Zinc Oxide–Silica Systems for Dental Composite Resins: Effect on Mechanical Properties
by Peyman Torkian, SayedMohsen Mortazavi Najafabadi, Majid Ghashang and Dariusz Grzelczyk
Materials 2023, 16(18), 6268; https://doi.org/10.3390/ma16186268 - 19 Sep 2023
Cited by 3 | Viewed by 1920
Abstract
The potential of glass ceramics as applicable materials in various fields including fillers for dental restorations is our guide to present a new procedure for improvements of the mechanical properties of dental composites. This work aims to use Zn2SiO4 and [...] Read more.
The potential of glass ceramics as applicable materials in various fields including fillers for dental restorations is our guide to present a new procedure for improvements of the mechanical properties of dental composites. This work aims to use Zn2SiO4 and SiO2–ZnO nano-materials as fillers to improve the mechanical properties of Bis-GMA/TEGDMA mixed dental resins. Zn2SiO4 and SiO2–ZnO samples were prepared and characterized by using XRD, FE-SEM, EDX, and FT-IR techniques. The XRD pattern of the SiO2–ZnO sample shows that ZnO crystallized in a hexagonal phase, while the SiO2 phase was amorphous. Similarly, the Zn2SiO4 sample crystallized in a rhombohedral crystal system. The prepared samples were used as fillers for the improvement of the mechanical properties of Bis-GMA/TEGDMA mixed dental resins. Five samples of dental composites composed of Bis-GMA/TEGDMA mixed resins were filled with 2, 5, 8, 10, and 15 wt% of SiO2–ZnO, and similarly, five samples were filled with Zn2SiO4 samples (2, 5, 8, 10, and 15 wt%). All of the 10 samples (A1A10) were characterized by using different techniques including FT-IR, FE-SEM, EDX, and TGA analyses. According to the TGA analysis, all samples were thermally stable up to 200 °C, and the thermal stability increased with the filler percent. Next, the mechanical properties of the samples including the flexural strength (FS), flexural modulus (FM), diameter tensile strength (DTS), and compressive strength (CS) were investigated. The obtained results revealed that the samples filled with 8 wt% of SiO2–ZnO and 10 wt% of Zn2SiO4 had higher FS values of 123.4 and 136.6 MPa, respectively. Moreover, 8 wt% of both fillers displayed higher values of the FM, DTS, and CS parameters. These values were 8.6 GPa, 34.2 MPa, and 183.8 MPa for SiO2–ZnO and 11.3 GPa, 41.2 MPa, and 190.5 MPa for the Zn2SiO4 filler. Inexpensive silica-based materials enhance polymeric mechanics. Silica–metal oxide nanocomposites improve dental composite properties effectively. Full article
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15 pages, 2022 KiB  
Article
Investigation of Spark Plasma Sintering on Microstructure-Properties of Zirconia Reinforced Fluormica Glass for Dental Restorations
by Sivaranjani Gali, Suhasini Gururaja, T. Niranjana Prabhu and Srikari Srinivasan
Materials 2023, 16(18), 6125; https://doi.org/10.3390/ma16186125 - 8 Sep 2023
Viewed by 2115
Abstract
Background: Conventional sintering methods of dental ceramics have limitations of high temperature and slow cooling rates with requirements of additional heat treatment for crystallization. Spark plasma sintering (SPS) is an emerging technique that has the potential to process dental restorations with dense microstructures [...] Read more.
Background: Conventional sintering methods of dental ceramics have limitations of high temperature and slow cooling rates with requirements of additional heat treatment for crystallization. Spark plasma sintering (SPS) is an emerging technique that has the potential to process dental restorations with dense microstructures and tailor-made clinically relevant properties with optimized processing parameters. This study explored the potential of the SPS of zirconia-reinforced fluormica glass (FM) for dental restorative materials. Methods: FM glass frit was obtained through the melt-quench technique (44.5 SiO2–16.7 Al2O3–9.5 K2O–14.5 MgO–8.5 B2O3–6.3 F (wt.%)). The glass frit was ball-milled with 20 wt.% of 3 mol% yttria-stabilized zirconia (FMZ) for enhanced fracture toughness. The mixtures were SPS sintered at a pressure of 50 MPa and a heating rate of 100 °C/min for 5 min with an increase in temperature from 650–750 °C–850 °C–950 °C. Phase analysis was carried out using XRD and microstructural characterization with SEM. Micro-hardness, nano-indentation, porosity, density, indentation fracture toughness, and genotoxicity were assessed. Conclusions: The increase in the SPS temperature of FMZ influenced its microstructure and resulted in reduced porosity, improved density, and optimal mechanical properties with the absence of genotoxicity on human gingival fibroblast cells. Full article
(This article belongs to the Special Issue Biomaterials Development and Evaluation for Dentistry)
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11 pages, 2691 KiB  
Article
Low-Temperature Fluoro-Borosilicate Glass for Controllable Nano-Crystallization in Glass Ceramic Fibers
by Qichao Zhao, Jianfeng Li, Tingyu Zha, Penghui Zhang, Yi Long and Zaijin Fang
Nanomaterials 2023, 13(10), 1586; https://doi.org/10.3390/nano13101586 - 9 May 2023
Cited by 4 | Viewed by 2050
Abstract
A fluorosilicate (FS) nano-crystallized glass ceramic (NGC) is one of the most commonly used gain materials for applications in optical devices due to its excellent thermal stability as well as high-efficiency luminescence. However, FS glass can hardly be used to prepare NGC fibers [...] Read more.
A fluorosilicate (FS) nano-crystallized glass ceramic (NGC) is one of the most commonly used gain materials for applications in optical devices due to its excellent thermal stability as well as high-efficiency luminescence. However, FS glass can hardly be used to prepare NGC fibers due to its high preparation temperature. Here, a series of low-temperature fluoro-borosilicate (FBS) glasses were designed for the fabrication of active NGC fibers. By modulating B2O3, the preparation temperature of FBS glass was reduced to 1050 °C, and the crystallization in FBS NGCs was more controllable than in FS NGC. The crystallization of the impure phase was inhibited, and single-phase rare earth (RE)-fluoride nanocrystals were controllably precipitated in the FBS NGCs. The 40Si-20B FBS NGC not only exhibited a higher optical transmittance, but the luminescence efficiency was also much higher than traditional FS NGCs. More importantly, NGC fibers were successfully fabricated by using the designed FBS glass as core glass. Nanocrystals were controllably precipitated and greatly enhanced, and upconversion luminescence was observed in NGC fibers. The designed FBS NGCs provided high-quality optical gain materials and offered opportunities for fabricating a wide range of NGC fibers for multiple future applications, including fiber lasers and sensors. Full article
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12 pages, 5125 KiB  
Article
Optimization of Electrical Properties of Nanocrystallized Na3M2(PO4)2F3 NASICON-like Glasses (M = V, Ti, Fe)
by Maciej Nowagiel, Anton Hul, Edvardas Kazakevicius, Algimantas Kežionis, Jerzy E. Garbarczyk and Tomasz K. Pietrzak
Coatings 2023, 13(3), 482; https://doi.org/10.3390/coatings13030482 - 21 Feb 2023
Cited by 3 | Viewed by 2091
Abstract
Recently, an interest in NASICON-type materials revived, as they are considered potential cathode materials in sodium–ion batteries used in large-scale energy storage. We applied a facile technique of thermal nanocrystallization of glassy analogs of these compounds to enhance their electrical parameters. Six nanomaterials [...] Read more.
Recently, an interest in NASICON-type materials revived, as they are considered potential cathode materials in sodium–ion batteries used in large-scale energy storage. We applied a facile technique of thermal nanocrystallization of glassy analogs of these compounds to enhance their electrical parameters. Six nanomaterials of the Na3M2(PO4)2F3 (M = V, Ti, Fe) system were studied. Samples with nominal compositions of Na3V2(PO4)2F3, Na3Ti2(PO4)2F3, Na3Fe2(PO4)2F3, Na3TiV(PO4)2F3, Na3FeV(PO4)2F3 and Na3FeTi(PO4)2F3 have been synthesized as glasses using the melt-quenching method. X-ray diffraction measurements were conducted for as-synthesized samples and after heating at elevated temperatures to investigate the structure. Extensive impedance measurements allowed us to optimize the nanocrystallization process to enhance the electrical conductivity of cathode nanomaterials. Such a procedure resulted in samples with the conductivity at room temperature ranging from 1×109 up to 8×105 S/cm. We carried out in situ impedance spectroscopy measurements (in an ultra-high-frequency range up to 10 GHz) and compared them with thermal events observed in differential thermal analysis studies. Full article
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21 pages, 5315 KiB  
Article
Photoluminescence Investigations of Dy3+-Doped Silicate Xerogels and SiO2-LaF3 Nano-Glass-Ceramic Materials
by Natalia Pawlik, Tomasz Goryczka, Ewa Pietrasik, Joanna Śmiarowska and Wojciech A. Pisarski
Nanomaterials 2022, 12(24), 4500; https://doi.org/10.3390/nano12244500 - 19 Dec 2022
Cited by 6 | Viewed by 1941
Abstract
In this work, the series of Dy3+-doped silicate xerogels were synthesized by sol-gel technique and further processed at 350 °C into SiO2-LaF3:Dy3+ nano-glass-ceramic materials. The X-ray diffraction (XRD) measurements, along with the thermal analysis, indicated that [...] Read more.
In this work, the series of Dy3+-doped silicate xerogels were synthesized by sol-gel technique and further processed at 350 °C into SiO2-LaF3:Dy3+ nano-glass-ceramic materials. The X-ray diffraction (XRD) measurements, along with the thermal analysis, indicated that heat-treatment triggered the decomposition of La(TFA)3 inside amorphous sol-gel hosts, resulting in the formation of hexagonal LaF3 phase with average crystal size at about ~10 nm. Based on the photoluminescence results, it was proven that the intensities of blue (4F9/26H15/2), yellow (4F9/26H13/2), and red (4F9/26H11/2) emissions, as well as the calculated yellow-to-blue (Y/B) ratios, are dependent on the nature of fabricated materials, and from fixed La3+:Dy3+ molar ratios. For xerogels, the emission was gradually increased, and the τ(4F9/2) lifetimes were elongated to 42.7 ± 0.3 μs (La3+:Dy3+ = 0.82:0.18), however, for the sample with the lowest La3+:Dy3+ molar ratio (0.70:0.30), the concentration quenching was observed. For SiO2-LaF3:Dy3+ nano-glass-ceramics, the concentration quenching effect was more visible than for xerogels and started from the sample with the highest La3+:Dy3+ molar ratio (0.988:0.012), thus the τ(4F9/2) lifetimes became shorter from 1731.5 ± 5.7 up to 119.8 ± 0.4 μs. The optical results suggest, along with an interpretation of XRD data, that Dy3+ ions were partially entered inside LaF3 phase, resulting in the shortening of Dy3+-Dy3+ inter-ionic distances. Full article
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37 pages, 10096 KiB  
Review
A Review on Photocatalytic Glass Ceramics: Fundamentals, Preparation, Performance Enhancement and Future Development
by Jun Wang, Mitang Wang, Yingliang Tian and Wei Deng
Catalysts 2022, 12(10), 1235; https://doi.org/10.3390/catal12101235 - 14 Oct 2022
Cited by 17 | Viewed by 4233
Abstract
Photocatalytic technology is considered as one of the most attractive and promising technologies to directly harvest, convert and store renewable solar energy for generating sustainable and green energy and a broad range of environmental applications. However, the use of a photocatalyst in powder [...] Read more.
Photocatalytic technology is considered as one of the most attractive and promising technologies to directly harvest, convert and store renewable solar energy for generating sustainable and green energy and a broad range of environmental applications. However, the use of a photocatalyst in powder or coating forms restricts its applications due to its disadvantages, such as difficulty in recovery of nano-powder, secondary pollution, low adhesion between photocatalytic coating and substrate material, short service life of photocatalytic film and so on. The investigation and application of photocatalytic glass-ceramics (PGCs) in water purification, bacterial disinfection, self-cleaning and hydrogen evolution have received extensive attention due to their inherent advantages of low cost, easy fabrication, transparency, chemical and mechanical stability. Real-time solutions to energy shortage and environmental pollution faced by the development of human society can be provided by rationally designing the chemical composition and preparation methods of glass ceramics (GCs). This review introduces the concept and crystallization mechanism of PGCs and expounds on the basic mechanism of photocatalysis. Then, the key point difficulties of GCs’ design are discussed, mainly including the methods of obtaining transparency and controlling crystallization technologies. Different modification strategies to achieve better photocatalytic activity are highlighted. Finally, we look forward to further in-depth exploration and research on more efficient PGCs suitable for various applications. Full article
(This article belongs to the Section Photocatalysis)
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11 pages, 3509 KiB  
Article
Assessment of Sand and Glass Industry in Saudi Arabia
by Essam R. I. Mahmoud, Awaluddin Mohamed Shaharoun, Abdulrahman Aljabri, Hamad Almohamadi and Mohammed Farhan
Sustainability 2022, 14(19), 12904; https://doi.org/10.3390/su141912904 - 10 Oct 2022
Cited by 1 | Viewed by 5768
Abstract
Although the economic value of glass products and its importance to the Saudi National Economy is vast, not much information is available about the current state of the art of the industry. Likewise, little information is available about geography, potential sites for mining [...] Read more.
Although the economic value of glass products and its importance to the Saudi National Economy is vast, not much information is available about the current state of the art of the industry. Likewise, little information is available about geography, potential sites for mining sand and the sand quality. This paper attempts to bridge this gap by presenting a feasibility study of fabricating normal glass and glass ceramics from Saudi Arabia’s domestically available raw materials. It discusses the current status of the glass industry in Saudi Arabia and the Middle East region. It also gives a brief explanation about the sand topography in Saudi Arabia. In order to determine the feasibility of fabricating glass using these raw materials, experimental data on the fabrication of normal glass and glass ceramics from indigenously available raw materials was obtained and reported as part of the findings of this paper. Firstly, normal transparent glass was able to be fabricated without any apparent large defects using sand collected from the Ar Rayis region in Saudi Arabia. Four nano-sized crystallization catalysts, namely VC, WC, TiC and Y2O3, were added to the constituents of the glass in 3 wt.%. For VC, the crystallization process was limited. The glass ceramics of WC consisted of multi-dimensional edges crystals which covered all the matrix. Gray crystalline whiskers were obtained by addition of TiC. The Y2O3- glass ceramics consisted of multi-directionally rosette crystals. Finally, the microhardness values of the added crystallization catalysts glass ceramics were obtained and found to be much higher compared to normal glass. The results show that glass of high quality can be produced specifically for the Ar Rayis region which would be of interest to researchers, the glass industry personnel and potential investors. Full article
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13 pages, 7326 KiB  
Article
Studies on δ-Bi2O3 Based Nanocrystalline Glass-Ceramics Stabilized at Room Temperature by Novel Methods
by Paulina Kruk-Fura and Jerzy E. Garbarczyk
Appl. Sci. 2022, 12(15), 7885; https://doi.org/10.3390/app12157885 - 5 Aug 2022
Cited by 2 | Viewed by 1937
Abstract
This study demonstrated for the first time that it is possible to prepare nanocrystalline δ-Bi2O3 that is stable at room temperature by twin-rollers and free cooling methods, using a ceramic crucible. The phase composition of prepared samples and upper limit [...] Read more.
This study demonstrated for the first time that it is possible to prepare nanocrystalline δ-Bi2O3 that is stable at room temperature by twin-rollers and free cooling methods, using a ceramic crucible. The phase composition of prepared samples and upper limit of the thermal stability of nanograins confined in an amorphous matrix were determined by the X-ray diffraction (XRD) method. The average size of crystallites and the microstructure of studied samples was determined by SEM and XRD methods. The average grain size varied from 38 to 85 nm, depending on the preparation technique; however, it was also observed that agglomerations consisted of smaller crystallites ca. 10–30 nm. Using the EDX method, it was found that a crucial role in the preparation of nanocrystalline δ-Bi2O3 glass-ceramics was played by Si and Al impurities and their glass forming oxides from ceramic crucible. By impedance spectroscopy (IS), the temperature dependencies of electric conductivity (via oxygen ions) were studied and the activation energies of conductivity were determined. Full article
(This article belongs to the Section Materials Science and Engineering)
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11 pages, 1560 KiB  
Article
Electrochemical Performance of Highly Conductive Nanocrystallized Glassy Alluaudite-Type Cathode Materials for NIBs
by Maciej Nowagiel, Mateusz J. Samsel, Edvardas Kazakevicius, Aldona Zalewska, Algimantas Kežionis and Tomasz K. Pietrzak
Energies 2022, 15(7), 2567; https://doi.org/10.3390/en15072567 - 1 Apr 2022
Cited by 2 | Viewed by 2055
Abstract
Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium-ion batteries. It has been demonstrated that optimized thermal nanocrystallization of glassy analogs of various cathode materials may lead to a significant increase in their electrical conductivity. In this paper, three [...] Read more.
Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium-ion batteries. It has been demonstrated that optimized thermal nanocrystallization of glassy analogs of various cathode materials may lead to a significant increase in their electrical conductivity. In this paper, three alluaudite-like glasses (Na2Fe3(PO4)3—FFF, Na2VFe2(PO4)3—VFF, and Na2VFeMn(PO4)3—VFM) were synthesized and subjected to an optimized thermal nanocrystallization. This procedure resulted in nanostructured samples with increased electrical conductivity at room temperature: 5×107 S/cm (FFF), 7×105 S/cm (VFM), and 6×104 S/cm (VFF). The nanocrystalline microstructure was also evidenced by ultra-high-frequency impedance spectroscopy (up to 10 GHz) and proposed electrical equivalent circuits. Prototype electrochemical cells were assembled and characterized with voltage cutoffs of 1.5 and 4.5 V. The electrochemical performance was, however, modest. The gravimetric capacity varied between the studied materials, but did not exceed 35 mAh/g. Capacity retention after ca. 100 cycles was satisfactory. Further optimization of the residual-glass-to-nanocrystallite volume ratio would be desirable. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for Li- and Na-Ion Batteries)
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16 pages, 2564 KiB  
Communication
Luminescence of SiO2-BaF2:Tb3+, Eu3+ Nano-Glass-Ceramics Made from Sol–Gel Method at Low Temperature
by Natalia Pawlik, Barbara Szpikowska-Sroka, Tomasz Goryczka, Ewa Pietrasik and Wojciech A. Pisarski
Nanomaterials 2022, 12(2), 259; https://doi.org/10.3390/nano12020259 - 14 Jan 2022
Cited by 12 | Viewed by 2547
Abstract
The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped [...] Read more.
The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped with Tb3+, Eu3+ ions were fabricated from amorphous xerogels at 350 °C. The analysis of the thermal behavior of fabricated xerogels was performed using TG/DSC measurements (thermogravimetry (TG), differential scanning calorimetry (DSC)). The crystallization of BaF2 phase at the nanoscale was confirmed by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), and the changes in silicate sol–gel host were determined by attenuated total reflectance infrared (ATR-IR) spectroscopy. The luminescent characterization of prepared sol–gel materials was carried out by excitation and emission spectra along with decay analysis from the 5D4 level of Tb3+. As a result, the visible light according to the electronic transitions of Tb3+ (5D47FJ (J = 6–3)) and Eu3+ (5D07FJ (J = 0–4)) was recorded. It was also observed that co-doping with Eu3+ caused the shortening in decay times of the 5D4 state from 1.11 ms to 0.88 ms (for xerogels) and from 6.56 ms to 4.06 ms (for glass-ceramics). Thus, based on lifetime values, the Tb3+/Eu3+ energy transfer (ET) efficiencies were estimated to be almost 21% for xerogels and 38% for nano-glass-ceramics. Therefore, such materials could be successfully predisposed for laser technologies, spectral converters, and three-dimensional displays. Full article
(This article belongs to the Special Issue Multifunctional Nanomaterials for Energy Applications)
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15 pages, 9841 KiB  
Article
Towards the High Phase Purity of Nanostructured Alluaudite-Type Glass-Ceramics Cathode Materials for Sodium Ion Batteries
by Maciej Nowagiel, Mateusz J. Samsel and Tomasz K. Pietrzak
Materials 2021, 14(17), 4997; https://doi.org/10.3390/ma14174997 - 1 Sep 2021
Cited by 12 | Viewed by 2810
Abstract
Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium ion batteries. In this paper, we strove to optimize various synthesis parameters of three alluaudite compositions (Na2Fe3(PO4)3—FFF, Na2VFe2(PO [...] Read more.
Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium ion batteries. In this paper, we strove to optimize various synthesis parameters of three alluaudite compositions (Na2Fe3(PO4)3—FFF, Na2VFe2(PO4)3—VFF, and Na2VFeMn(PO4)3—VFM) to obtain nanostructured alluaudite-type glass-ceramics with high phase purity. We systematically investigated the role of the chemical reactions, temperature and time of melting, cooling rate, and reducing factors on the quality of the final products. A detailed synthesis protocol along with X-ray diffractometry, thermal analysis, scanning electron microscopy imaging, and electrical conductivity measurements (with impedance spectroscopy) are reported. As a result, a significant increase of the conductivity was observed in the nanomaterials. The highest value was reached for the VFF composition and was equal to 6×104 S/cm at room temperature. Full article
(This article belongs to the Special Issue Functional Nanomaterials for a Better Life)
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24 pages, 23758 KiB  
Review
Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing
by Tomasz K. Pietrzak, Marek Wasiucionek and Jerzy E. Garbarczyk
Nanomaterials 2021, 11(5), 1321; https://doi.org/10.3390/nano11051321 - 17 May 2021
Cited by 37 | Viewed by 4587
Abstract
This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting [...] Read more.
This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting oxide glasses. Various nanostructured systems have been described, including glass-ceramics based on ion conductive glasses (silver iodate and bismuth oxide ones) and electronic conductive glasses (vanadate-phosphate and olivine-like ones). Most systems under consideration have been studied with the practical aim of using them as electrode or solid electrolyte materials for rechargeable Li-ion, Na-ion, all-solid batteries, or solid oxide fuel cells. It has been shown that the conductivity enhancement of glass-ceramics is closely correlated with their dual microstructure, consisting of nanocrystallites (5–100 nm) confined in the glassy matrix. The disordered interfacial regions in those materials form “easy conduction” paths. It has also been shown that the glassy matrices may be a suitable environment for phases, which in bulk form are stable at high temperatures, and may exist when confined in nanograins embedded in the glassy matrix even at room temperature. Many complementary experimental techniques probing the electrical conductivity, long- and short-range structure, microstructure at the nanometer scale, or thermal transitions have been used to characterize the glass-ceramic systems under consideration. Their results have helped to explain the correlations between the microstructure and the properties of these systems. Full article
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