Glass Ceramic Fibers Research Articles

Micro-scale abrasion wear of novel biomedical PEEK-matrix composites for restorative dentistry

Novel PEEK-based composites have been studied to replace metallic biomedical implant and prostheses although the influence of aggressive oral conditions should be understood such as wear in the presence of toothpaste abrasive particles. The main aim of this study was to assess the micro-abrasion performance of novel PEEK-based composites embedding biocompatible inorganic fillers composed of (LZSA) lithium-silicate glass ceramic or (NASF) natural silica fibers. PEEK powders were mixed with 10 and 30 wt% LZSA or NASF to produce composite structures by using hot pressing technique. After polishing and cleaning procedures, test surfaces were assessed by micro-scale abrasion tests at on 0.8 N at 600 ball revolutions in contact with an abrasive suspension of 6 wt% amorphous silica particles with mean size at 8–10 μm. The worn and unworn surfaces were inspected by scanning electron microscopy (SEM) and optical profilometry. SEM images revealed aligned abrasion grooves on all the test surfaces. The largest damaged area was noticed on PEEK free of inorganic fillers while the lowest micro-abrasion damage was recorded on PEEK embedding 10%LZSA. The micro-abrasion resistance of PEEK-LZSA composites was negatively affected by the increase of inorganic content as seen on 30%LZSA. However, PEEK-based composites showed a higher micro-abrasion wear resistance than that on non-reinforced PEEK. The wear resistance can be enhanced by adding an adequate content and shape of inorganic fillers. Further studies should investigate the effect of morphology and properties of inorganic fillers to improve the wear performance of PEEK-based composites.

微晶玻璃光纤的研究进展

微晶玻璃光纤的研究进展

A facile and scalable process to synthesize flexible lithium ion conductive glass-ceramic fibers.

Solid-state electrolytes have emerged as a promising alternative to existing liquid electrolytes for next-generation flexible Li metal batteries with enhanced safety and stability. Nevertheless, the brittleness and inferior room temperature conductivity are major obstacles for practical applications. Herein, for the first time, we have fabricated a flexible lithium ion conductive glass-ceramic fiber by using a melt-spun homogeneous NASICON-type structured Li1.5Al0.5Ge1.5(PO4)3 (LAGP) glass melt and annealed at 825 °C. The annealed samples exhibited a higher lithium ion conductivity than the air-quenched sample due to the presence of a well-crystallized crystal grain in the annealed sample. Meanwhile, the ionic conductivity has shown an inverse relationship with the diameter of annealed LAGP glass-ceramic fibers. The results revealed that the annealed glass-ceramic fiber, with a diameter of 10 μm, resulted in lithium ion conductivity of 8.8 × 103 S cm−1 at room temperature.

Enhanced single-mode fiber laser emission by nano-crystallization of oxyfluoride glass-ceramic cores

We have demonstrated enhanced 1.55 μm single-mode fiber laser output in KYF4:Er3+/Yb3+ nanocrystal embedded oxyfluoride glass ceramic fibers.

Tunable upconversion emission in NaLuF4-glass-ceramic fibers doped with Er3+ and Yb3.

Novel glass-ceramic optical fibers containing NaLuF4 nanocrystals doped with 0.5ErF3 and 2YbF3 (mol%) have been prepared by the rod-in-tube method and controlled crystallization. NaLuF4 nanocrystals with a size around 20 nm are obtained after heat treatment at 600 °C. Intense upconverted green and red emissions due to (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively, together with a blue emission due to 2H9/2 → 4I15/2 transition have been observed under excitation at 980 nm. The intensity of the green and red upconversion bands shows a nearly linear dependence on the excitation power which can be explained by saturation effects in the intermediate energy states and proves that a sensitized energy transfer upconversion process is responsible for the population of the emitting levels of Er3+ ions. The upconversion emission color changes from yellow to green by increasing the excitation power density which allows to manipulate the color output of the Er3+ emission in the glass-ceramic fibers. The tunable emission color is easily detected with the naked eye. This interesting characteristic makes these glass-ceramic fibers promising materials for photonic applications.

The role of phonons in the luminescence characteristics of SICLOF oxyfluoride glass and glass-ceramic fibers doped with Er3+/Yb3+

Recently developed SICLOF oxyfluoride glass and glass-ceramic fibers doped with Er3+/Yb3+ have been prepared for fiber applications and optically characterized. The luminescence efficiency of glass-ceramic fiber appeared to be two times higher than that for glass fiber. An interesting dependence of the luminescence intensity around 1530 nm on temperature has been observed as the temperature was altered in the range of 5–350 K. For glass-ceramic fibers this dependence was different from that for glass fibers. The difference has been interpreted with use of kinetic equations and values of maximum phonon energies (ħωmax) different for glass-ceramic and glass fibers. The obtained fittings indicate that during thermal treatment the ħωmax value decreases by 40–50 cm−1. We also estimate how does such a change affect the luminescence efficiency and find that the phonon energy reduction can be responsible for at the most 28% of the luminescence efficiency improvement.

Ytterbium-doped oxyfluoride nano-glass-ceramic fibers for laser cooling

Ytterbium (Yb3+)-doped oxyfluoride SiO2-Al2O3-CdF2-PbF2-YF3 glass and nano-glass-ceramic (i.e. glass-ceramics containing nanocrystals) single-index optical fibers were fabricated using two methods: by traditional glass preform drawing and by the crucible technique (‘direct-melt process’). The latter technique permitted the fabrication of perfectly vitreous optical fibers (of about 200 µm diameter), leading subsequently to the fabrication of nano glass-ceramic fibers by a well-controlled heat-treatment process above the glass transition temperature. Structural characterizations have (i) confirmed the vitreous state (absence of crystals) of the glass preforms and the glass fiber obtained from the ‘direct-melt process’ and, (ii) evidenced the formation of Pb1-x-y-zCdxYyYbzF2 (x + y + z ≈0.3-0.4) fluorite nanocrystals in the final glass-ceramic fibers. In particular, the nanocrystal size was found to be rather homogenous and smaller than 10 nm from TEM measurements for the nano-glass-ceramic fibers produced by controlled crystallization. The absolute photoluminescence quantum efficiency, mean fluorescence wavelength and anti-Stokes fluorescence of the Yb3+-doped fibers were measured upon laser excitation at wavelengths of 940 nm, 975 nm and 1030 nm, respectively. As expected, higher photoluminescence quantum yield in the near infrared (0.95, close to unity) was obtained for the nano-glass-ceramic fiber when compared with the glass-fiber. Theoretical calculations were also carried out, showing that optical refrigeration would be achievable from these chemically stable and durable nano-glass-ceramic fibers provided that 95% (segregation ratio) of Yb3+ ions are incorporated into the fluorite nanocrystals.

Glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals for frequency conversion of lasers

A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers.

Precisely controllable fabrication of Er3+-doped glass ceramic fibers: novel mid-infrared fiber laser materials

We demonstrated remarkably enhanced 2.7 μm emission in glass-ceramic (GC) fibers containing NaYF4:Er3+ nanocrystals with 980 nm excitation for the first time.

Oxyfluoride glass–ceramic fibers doped with Nd3+: structural and optical characterization

Selective excitation in an oxyfluoride glass–ceramic optical fiber containing LaF3nanocrystals doped with Nd3+.

Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb3+-Er3+ codoped CaF2 nanocrystals

Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb3+-Er3+ codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

Controlling the Metastable States of Glasses by External Fields

Glass is a noncrystalline amorphous solid showing glass transition characteristic. It can transform from one metastable state to another metastable or stable state in an external field. In glasses, novel functions can be achieved if we control the status, morphology, and distribution of external field‐induced structures. In this article, we review controlled crystallization of glass by the external fields, that is, control of ligand field, local symmetry, and energy transfer of active ions, etc. by temperature field to achieve efficient broadband near‐infrared emission and optical amplification. We also discussed highly localized crystallization in glass by electron beam and femtosecond laser. Finally, we introduced a novel process for the fabrication of glass ceramic fibers.

Ni(2+) doped glass ceramic fiber fabricated by melt-in-tube method and successive heat treatment.

Glass ceramic fibers containing Ni(2+) doped LiGa(5)O(8) nanocrystals were fabricated by a melt-in-tube method and successive heat treatment. Fiber precursors were prepared by drawing at high temperature where fiber core glass was melted while fiber clad glass was softened. After heat treatment, LiGa(5)O(8) nanocrystals were precipitated in the fiber core. Excited by 980 nm laser, efficient broadband near-infrared emission was observed in the glass ceramic fiber compared to that of precursor fiber. The melt-in-tube method can realize controllable crystallization and is suitable for fabrication of novel glass ceramic fibers. The Ni(2+)-doped glass ceramic fiber is promising for broadband optical amplification.

Investigation of the mechanical properties and fracture morphology of glass ceramic fibers

The mechanical properties of magnesium aluminium silicate (MAS) and lithium aluminium silicate (LAS) single fibers were investigated. The fibers were prepared using different methods namely melt drawing (MAS) and continuous drawing (LAS) respectively. The glass ceramic fibers were subjected to the optimized thermal treatments and tested using the single fiber test method (SFT) in order to obtain and evaluate their mechanical properties before and after crystallization. The tested fibers were further characterized by scanning electron microscopy (SEM) and the results showed that the average tensile strength values were a function of the gage length and the fiber diameters.

Optical properties and crystallization behavior of 45GeS2·30Ga2S3·25Sb2S3 chalcogenide glass

Glass-ceramics containing Ga2S3 nano-crystals were reproducibly fabricated from the 45GeS2·30Ga2S3·25Sb2S3 chalcogenide glass by heat treatment at 335°C (Tg+30°C) for different durations. The obtained glass-ceramics are still transparent in the IR region and show improved thermal stability. Crystallization mechanism was investigated using the non-isothermal method. The results show that the crystallization rate constant K at 335°C for the Ga2S3 phase is about 2 orders of magnitude larger than that of the second crystallization peak in the DSC curve. So it is easy to control the crystallization process with only Ga2S3 crystallites precipitated. With the above advantages, it has a great potential for drawing infrared transmitting glass-ceramic fibers with improved mechanical properties and enhanced luminescence for application in optical amplifiers.

Preparation and properties of barium-ferrite-containing glass ceramic fibers via an electrospinning/sol–gel process

Barium-ferrite-containing glass ceramic fibers were successfully prepared by the combination of a sol–gel process and electrospinning technique using basic iron formate, barium acetate and boric acid as the starting materials. After leaching of barium borate matrix, pure phase BaFe12O19 fibers were obtained. The relationship of aged time and viscosity of the precursor solution was studied and the results showed that the viscosity corresponding to the spinnable state was 1–4 Pa s. The morphology, structure and magnetic properties of the obtained fibers were characterized with scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis–differential scanning calorimetry, vibrating sample magnetometer. The X-ray diffraction results indicate that only the M-type Ba-ferrite and Ba-borate exist. The fibers had rough surface and hollow structure with the diameter no more than 1 μm. The fibers were composed of 40 nm BaFe12O19 nanoparticles embedded in the borate matrix. The coercivity and saturation magnetization of the synthesized fibers were 4,106.9 Oe and 17.8 emu/g, respectively.

Yb-doped yttria–alumino–silicate nano-particles based optical fibers: Fabrication and characterization

An efficient method to fabricate transparent glass ceramic fibers containing in-situ grown Yb 3+ doped oxide nano-particles based on yttria–alumino–silicate glass is presented. These large-mode area Yb 3+ doped fibers having a core diameter around 25.0 μm were drawn by a proper control over the involved process parameters; by this, the size of nano-particles was maintained within 5–10 nm. The main spectroscopic and laser properties of the fabricated fibers along with the nano-structuration results are reported. These results reveal that the developed method offers new scopes for the contemporary Yb 3+ fiber based devices.

Angiogenic effect induced by mineral fibres

Due to the toxic effect of asbestos, other materials with similar chemical–physical characteristics have been introduced to substitute it. We evaluate the angiogenic effect of certain asbestos substitute fibres such as glass fibres (GFs), ceramic fibres (CFs) and wollastonite fibres (WFs) and then compare angiogenic responses to those induced by crocidolite asbestos fibres (AFs). An in vitro model using human endothelial cells in small islands within a culture matrix of fibroblasts (Angio-Kit) was used to evaluate vessel formation. The release of IL-6, sIL-R6, IL-8, VEGF-A and their soluble receptors, sVEGFR-1, sVEGFR-2, was determined in the conditioning medium of Angio-Kit system after fibre treatment. ROS formation and cell viability were evaluated in cultured endothelial cells (HUVEC). To evaluate the involvement of intracellular mechanisms, EGFR signalling, ROS formation and nuclear factor-κB (NFκB) pathway were then inhibited by incubating HUVEC cells with AG1478, NAC and PDTC respectively, and the cytokine and growth factor release was analyzed in the culture medium after 7 days of fibre incubation. Among the mineral fibres tested, WFs markedly induced blood vessel formation which was associated with release of IL-6 and IL-8, VEGF-A and their soluble receptors. ROS production was observed in HUVEC after WFs treatment which was associated with cell cytotoxicity. The EGFR-induced ERK phosphorylation and ROS-mediated NFκB activation were involved in the cytokine and angiogenic factor release. However, only the EGFR activation was able to induce angiogenesis. The WFs are potential angiogenic agents that can induce regenerative cytokine and angiogenic factor production resulting in the formation of new blood vessels.

The microstructure of erbium–ytterbium co-doped oxyfluoride glass–ceramic optical fibers

Oxyfluoride transparent glass–ceramics combine some features of glasses (easier shaping or lower than single crystals cost of fabrication) and some advantages of rare-earth doped single crystals (narrow absorption/emission lines and longer lifetimes of luminescent levels). Since the material seems to be promising candidate for efficient fiber amplifiers, the manufacturing as well as structural and optical examination of the oxyfluoride glass–ceramic fibers doped with rare-earth ions seems to be a serious challenge. In the first stage oxyfluoride glasses of the following compositions 48SiO2–11Al2O3–7Na2CO3–10CaO–10PbO–11PbF2–3ErF3 and 48SiO2–11Al2O3–7Na2CO3–10CaO–10PbO–10PbF2–3YbF3–1ErF3 (in molar%) were fabricated from high purity commercial chemicals (Sigma–Aldrich). The fabricated glass preforms were drawn into glass fibers using the mini-tower. Finally, the transparent Er3+ doped and Er3+/Yb3+ co-doped oxyfluoride glass–ceramic fibers were obtained by controlled heat treatment of glass fibers. The preceding differential thermal analysis (DTA) studies allowed estimating both the fiber drawing temperature and the controlled crystallization temperature of glass fibers. X-ray diffraction examination (XRD) at each stage of the glass–ceramic fibers fabrication confirmed the undesirable crystallization of preforms and glass fibers has been avoided. The fibers shown their mixed amorphous–crystalline microstructure with nano-crystals of size even below 10nm distributed in the glassy host. The crystal structure of the grown nano-crystals has been determined by XRD and confirmed by electron diffraction (SAED). Results obtained by both techniques seem to be compatible: Er3FO10Si3 (monoclinic; ICSD 92512), Pb5Al3F19 (triclinic; ICSD 91325) and Er4F2O11Si3 (triclinic; ICSD 51510) against to initially expected PbF2 crystals.

Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

Rare earth (RE)-doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of postceramming. The main characteristics of the RE-doped oxide nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline-earth element used as phase-separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However, in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporating new doped materials to realize active optical fibers for constructing lasers and amplifiers.