Design, processing and characterization of glass fibers and coatings for healthcare industries

In this PhD, several bioactive phosphate glasses doped with erbium ions (Er3+) were synthesized and characterized in order to develop new bioactive fiber sensors for medical diagnostics and therapeutics in healthcare applications. Firstly, Er3+-doped phosphate glasses within the glass system P2O5-SrO-Na2O were fabricated using the melt-quenching technique. The glasses were prepared with different compositions and analyzed to understand the impact of the addition of Al2O3, TiO2 or ZnO on the thermal, structural and luminescence properties of the glasses. The results showed that with the addition of Al2O3 and TiO2 the phosphate network became more connected, whereas the addition of ZnO did not modify the optical, thermal and structural properties but it led to an enhanced fluorescence emission as compared to the other glasses. Secondly, glass-ceramics (GCs) were processed by heat-treating the glasses to induce in-situ crystal growth. The effect of the crystallization on the properties of phosphate glasses containing Al2O3, TiO2 or ZnO was investigated. The structural, optical, and spectroscopic characterization allowed assessing the occurrence and properties of the Er3+-doped crystals in the glasses. Different crystal phases were obtained depending on the glass composition but Sr(PO3)2 was identified in all the glasses. Moreover, the surface crystallization of the GCs was increased along with the duration of the heat treatment. However, the site of the Er3+ ions was not strongly affected by the heat treatment except for the reference GC, where an increase of the luminescence properties was observed after the heat treatment probably due to the incorporation of Er3+ ions into the crystals. Thirdly, particles-containing glasses were prepared using the direct doping method. A series of different Er3+-doped Al2O3, TiO2, ZnO and ZrO2 nano- and microparticles were synthesized using soft chemistry and then were added to phosphate-based glass batches prior to and after the melting. The survival and dispersion of the particles were optimized in order to increase the luminescence properties of the glasses. As evidenced by the morphological and compositional analyses, the Er3+ ions diffused from the particles to the glass matrix and no improvement of the spectroscopic properties was observed. A large amount of Er3+-doped particles were dissolved into the glasses probably due to the high temperatures achieved during the melting. As an alternative, glasses with different composition and lower melting temperatures were tested. The last part of the project was the production and characterization of a multimode optical fiber made from phosphate-based glasses. The core composition was 0.25 Er2O3 – 97.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 2.5 ZnO, while the cladding composition was 98.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 1.75 ZnO. The cladding component was processed using the rotational casting technique, and the preform was successfully drawn into an optical fiber. This novel optical fiber was found to be able to allow in-line monitoring of the fiber dissolution in H3PO4 and in simulated body fluid (SBF) solution. Bioactivity of the fiber was also assessed by the formation of a hydroxylapatite layer at the surface of the fiber after 4 weeks of immersion in SBF solution at room temperature. In this thesis, a bioactive fiber sensor able to monitor its optical properties and in vitro reactivity was reported. This research activity demonstrates as a proof of principle the idea of tracking the bio-response of a bioactive optical fiber “in vivo”

Effect of the addition of Al2O3, TiO2 and ZnO on the thermal, structural and luminescence properties of Er3+-doped phosphate glasses

Er-doped phosphate glasses were fabricated by melt-quenching technique. The changes in their thermal, structural and luminescence properties with the addition of Al2O3, TiO2 or ZnO were studied. Physical and thermal properties were investigated through density measurement and differential thermal analysis. Structural characterization was performed using the Raman and Infrared spectroscopy. In order to study the influence of the composition on the luminescence properties of the glasses, the refractive index, the luminescence spectra and the lifetime values were measured. The results show that with the addition of Al2O3 and TiO2 the phosphate network becomes more connected increasing the glass transition temperature, whereas the addition of ZnO does not show significant changes in the optical, thermal and structural properties but it leads to a larger emission cross-section at 1540 nm as compared to the other glasses. As the site of the Er3+ is not strongly affected by the change in the glass composition, we think that the emission properties of the glasses depend on the glass structure connectivity, which has an impact on the Er3+ ions solubility.Comment: 32 pages, 9 figures, 1 tabl

Effect of Partial Crystallization on the Structural and Luminescence Properties of Er3+-Doped Phosphate Glasses

Er-doped phosphate glass ceramics were fabricated by melt-quenching technique followed by a heat treatment. The effect of the crystallization on the structural and luminescence properties of phosphate glasses containing Al2O3, TiO2, and ZnO was investigated. Themorphological and structural properties of the glass ceramics were characterized by Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), and micro-Raman spectroscopy. Additionally, the luminescence spectra and the lifetime values were measured in order to study the influence of the crystallization on the spectroscopic properties of the glasses. The volume ratio between the crystal and the glassy phases increased along with the duration of the heat treatment. The crystallization of the glass ceramics was confirmed by the presence of sharp peaks in the XRD patterns and different crystal phases were identified depending on the glass composition. Sr(PO3)2 crystals were found to precipitate in all the investigated glasses. As evidenced by the spectroscopic properties, the site of the Er3+ ions was not strongly affected by the heat treatment except for the fully crystallized glass ceramic which does not contain Al2O3, TiO2, and ZnO. An increase of the lifetime was also observed after the heat treatment of this glass. Therefore, we suspect that the Er3+ ions are incorporated in the precipitated crystals only in this glass ceramic

Design, Synthesis, and Structure-Property Relationships of Er3+-Doped TiO2 Luminescent Particles Synthesized by Sol-Gel

Titania particles doped with various concentrations of Erbium were synthesized by the sol-gel method followed by different heat treatments. The shape and the grain growth of the particles were noticeably affected by the concentration of Erbium and the heat treatment conditions. An infrared emission at 1530 nm, as well as green and red up-conversion emissions at 550 and 670 nm, were observed under excitation at 976 nm from all of the synthesized particles. The emission spectra and lifetime values appeared to be strongly influenced by the presence of the different crystalline phases. This work presents important guidelines for the synthesis of functional Er3+-doped titania particles with controlled and tailored spectroscopic properties for photonic applications

Ternary borosilicates as potential cladding glasses for semiconductor core optical fibers

Our study advances the development of new ternary silicate glasses for use as a designed cladding for semiconductor core optical fibers using molten core draw process. In order to fabricate high‐quality hybrid fibers (homogeneous core shape, low amount of bubbles, low internal stress, no cracking), oxide glasses are the best choice as cladding materials. These glasses should be engineered with tailored thermal properties (coefficient of thermal expansion (CTE) and drawing temperature) so they match those of the semiconductor. Glasses in the system (50SiO2‐(20 − x)Na2O‐(25 + x)B2O3‐5MO) with x = 0 and 10 and MO = ZnO, TiO2, GeO2, Ga2O3, and Al2O3 and in the system 50SiO2‐10Na2O‐(40 − y)B2O3‐ yTiO2 with y = 0, 1.25, 2.5, and 5 were investigated. Their thermal properties were measured and discussed with regard to the glass structure analyzed using FTIR spectroscopy. Due to their rigid network, which leads to beneficial thermal properties including low CTE (~5 ppm K−1), the Ge‐containing glass with x = 10 is a promising cladding candidate when preparing a Ge core fiber and the Ga or Zn‐ containing glasses when preparing an InAs core

Spectroscopic Properties of Er3+-Doped Particles-Containing Phosphate Glasses Fabricated Using the Direct Doping Method

The effect of the incorporation of Er2O3-doped particles on the structural and luminescence properties of phosphate glasses was investigated. A series of different Er2O3-doped TiO2, ZnO, and ZrO2 microparticles was synthesized using soft chemistry and then added into various phosphate glasses after the melting at a lower temperature than the melting temperature. The compositional, morphological, and structural analyses of the particles-containing glasses were performed using elemental mapping by field emission-scanning electron microscopy (FE-SEM) with energy dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD). Additionally, the luminescence spectra and the lifetime values were measured to study the influence of the particles incorporation on the spectroscopic properties of the glasses. From the spectroscopic properties of the glasses with the composition 50P2O5-40SrO-10Na2O, a large amount of the Er2O3-doped particles is thought to dissolve during the glass melting. Conversely, the particles were found to survive in glasses with a composition 90NaPO3-(10 − x)Na2O-xNaF (with x = 0 and 10 mol %) due to their lower processing temperature, thus clearly showing that the direct doping method is a promising technique for the development of new active glasses