Additive manufacturing offers new opportunities for designing complex glass preforms that cannot be achieved by conventional methods. In this work, we demonstrate the fabrication of microstructured chalcogenide-glass fibers for mid-infrared sensing using a filamentation 3D-printing process. Two fiber architectures were produced: a conventional exposed-core fiber (ECF) and a novel Y-shaped exposed-core fiber (Y-ECF), made possible only through additive manufacturing of the preforms. Both fibers exhibit attenuation below 4 dB/m in the 3–10 μm wavelength range with a minimum attenuation of 0.5 dB/m at 5.5 μm. Fiber evanescent wave spectroscopy (FEWS) measurements performed on ethanol reveal that the printed fibers outperform a standard single-index TAS fiber. The Y-ECF shows the highest sensitivity due to its fully open geometry and thin Y-core arms, which enhance the evanescent field and interaction with the surrounding medium. These results highlight the potential of 3D printing for rapid prototyping of advanced microstructured infrared fibers and open new perspectives for chemical and biological sensing in the mid-infrared.

In recent years, a growing interest has settled for optical materials and fibers for the mid infrared (mid-IR) region. This interest originates from societal needs for health and environment for instance, and also from demand for defence applications. Indeed, the mid-IR spectral region contains the atmospheric transparent windows (3-5 mu m) and (8-12 mu m) where thermal imaging (military and civilian) can take place. The elaboration of chalcogenide microstructured optical fibers (MOFs) permits to combine the mid infrared transmission of chalcogenide glasses up to 18 mu m and the unique optical properties of MOFs thanks to the high degree of freedom in the design of their geometrical structure. In this context, additive manufacturing of glass materials appears as an attractive technique to achieve more elaborate designs that can hardly be obtained using more common methods such as the stack-and-draw or molding. Taking advantages of the specific physical properties of chalcogenide glasses such as low T-g and extrusion temperature, we have shown that chalcogenide preforms can be rapidly obtained by fused deposition modeling (FDM) using a customized RepRap-style 3D printed fed with chalcogenide glass rods. Such as-prepared preforms can be drawn into microstructured chalcogenide optical fibers.

Lanthanum oxysulfide (La2O2S) was investigated as an effective doping matrix for the development of Er3+, Yb3+, Tm3+ tri-doped phosphors emitting white light. The powders were prepared by combustion synthesis and subsequently post-sulfurized under H2S/N2. They were characterized using Powder X-Ray Diffraction, FourierTransform Infrared Spectroscopy, Scanning Electron Microscopy and thermogravimetric analysis to assess their purity, morphology and thermal stability. The excitation, down-conversion and up-conversion properties of the phosphors were then studied using UV/Visible/NIR and fluorescence spectroscopy. Although white emission was not achieved with the studied compositions, a mechanism for up-conversion energy transfer in the tri-doped samples is proposed.

Barium lanthanum ternary sulfide (compositions within the BaLa2S4- γ-La2S3 solid solution of cubic Th3P4-type structure, referred to as BLS) was investigated as a novel infrared transparent ceramic for applications as external structural window material. This research marks the initial efforts to consolidate BLS powders into dense ceramics and reports, for the first time, the processing of polycrystalline BLS infrared transparent ceramics. The powders were produced through a combustion synthesis method followed by a sulfurization treatment in pure H2S. Sintering was carried out using hot-pressing and natural sintering. The characteristics of the powders and ceramics (purity, morphology, microstructure and optical transmission) are detailed and compared to evaluate the effectiveness of the two sintering techniques. A peak transmission of 20% at 16.5 μm was achieved for 1.4 mm-thick ceramics that were hot-pressed for 2 h at 1250 °C and subsequently annealed for 12 h at 1250 °C in pure H2S. With an extended transparency window (up to 20 μm, compared with 12 μm for ZnS), BLS polycrystalline ceramics are uniquely suited for use in harsh environments for space applications in both civil and military fields.

Fluoride glasses, particularly ZBLAN, exhibit exceptional optical properties, including low dispersion, high transmittance, and broad transparency in the mid-infrared spectrum. These characteristics make them highly attractive for applications such as mid-IR lasers, spectroscopy, and optical fiber technologies. In this study, we explore the feasibility of 3D printing ZBLAN glass using a fused filament fabrication (FFF) approach. The synthesis of high-purity ZBLAN glass rods was carried out, followed by an in-depth analysis of their thermal properties to determine optimal processing conditions. By adjusting extrusion temperatures and printing parameters, we successfully demonstrated the deposition of fluoride glass layers. The glassy state of the printed ZBLAN was verified, and a transmission of over 50% was achieved with the 3D-printed glass. This work represents a significant step toward additive manufacturing of advanced optical components, paving the way for new applications in infrared optics, fiber preforms, and customized glass microstructures. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Thin films with compositions equally distributed through GaSb-GaTe and GaSb-Te tie-lines were fabricated by radio-frequency magnetron co-sputtering. Several characterization techniques (scanning electron microscopy with energy-dispersive X-ray analysis, temperature dependent grazing incidence X-ray diffraction, Raman scattering spectroscopy, variable angle spectroscopic ellipsometry and sheet resistance temperature dependences) were employed to evaluate the properties of both as-deposited and annealed Ga-Sb-Te films. The change in the crystallization temperature influenced by composition variations is studied along with the change in the optical properties upon crystallization induced by annealing. The optical contrast between the annealed and amorphous states at a wavelength of 405 nm reaches a value of similar to 1.85 which is comparable with that in the case of commercially used Ge2Sb2Te5. All films showed a drop in temperature-dependent sheet resistance (similar to 4-7 orders of magnitude) except for Ga5Sb2Te3 and Ga5SbTe4. The results obtained from X-ray diffraction reveal Sb, GaSb, gallium antimony telluride together with Sb2Te3 and Te as possible phases which appear in the films after annealing. Additionally, Raman spectra revealed vibrational modes between Ga and Sb, vibrations of Sb-Sb bonds, vibrations of Te-Te and vibrations of Sb-Te. Changes between amorphous and crystalline phase of thin films with compositions equally distributed through GaSb-GaTe and GaSb-Te tie-lines fabricated by radio-frequency magnetron co-sputtering were studied.

This study explores the use of additive manufacturing to create ceramic dielectric resonators with controlled permittivity through the incorporation of air inclusions. Cylindrical samples of alumina and zirconia were fabricated with varying air volume fractions. Results showed that increasing air inclusions up to 95.5% reduced the permittivity from 9.4 to 1.3 in alumina and from 32.7 to 6.6 in zirconia. The effectiveness of these materials was demonstrated in antenna applications.

This work focuses on the realization of ceramic dielectric resonators with porous and complex geometry using additive manufacturing to control their effective permittivity. Several cylindrical alumina and zirconia samples integrating different volume fractions of air inclusions were developed and characterized. By incorporating up to 95.5 vol% of inclusions, we reduced the effective permittivity from 9.4 to 1.3 for alumina and from 32.7 to 7.8 for zirconia. The effectiveness of these samples in antenna applications was also demonstrated.

Ce3+-doped and Ce3+/Mn2+ co-doped calcium carbodiimide (CaCN2) phosphors were synthesized from doped calcium carbonate and carbon nitride by a solid-state reaction at 700 °C under flowing NH3 using a very short reaction time (1 h). The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated. Single-doped CaCN2:Ce3+ exhibits a blue emission under near-ultraviolet activation (386 nm) corresponding to the 5d1 → 2F5/2 and 5d1 → 2F7/2 transitions of Ce3+. Maximum emission is obtained at temperatures lower than 150 K and then progressively decreases up to 387 K, with an 80% drop in the emission at room temperature. Efficient energy transfers from Ce3+ to Mn2+ via a non-radiative dipole–dipole mechanism are evidenced for the co-doped samples, leading to various colored phosphors under near-ultraviolet activation (386 nm). The emission color of the obtained phosphors can be modulated from blue to red through a shade of white depending on the sensitizer/activator ratio.

In recent years, a growing interest has settled for optical materials and fibers for the mid infrared (mid-IR) region. This interest originates from societal needs for health and environment for instance, and also from demand for defence applications. Indeed, the mid-IR spectral region contains the atmospheric transparent windows (3-5 μm) and (8-12 μm) where thermal imaging (military and civilian) can take place. The elaboration of chalcogenide microstructured optical fibers (MOFs) permits to combine the mid infrared transmission of chalcogenide glasses up to 18 μm to the unique optical properties of MOFs thanks to the high degree of freedom in the design of their geometrical structure. In this context, additive manufacturing of glass materials appears as an attractive technique to achieve more elaborate designs that can hardly be obtain using more common methods such as the stack-and-draw or molding. Taking advantages of the specific physical properties of chalcogenide glasses such as low Tg and extrusion temperature, we have shown that chalcogenide preforms can be rapidly obtained by fused deposition modeling (FDM) using a customized RepRap-style 3D printed fed with chalcogenide glass rods. Such as-prepared preforms can be drawn into chalcogenide optical fibers. Those early-stage results open a new way for the elaboration of chalcogenide MOFs.

Lanthanum oxysulfide (La2O2S) was investigated as infrared transparent ceramic to benefit from stronger chemical bonds and superior mechanical performances to that of non-oxide benchmark infrared materials. La2O2S ceramics were processed by hot-pressing powders prepared by combustion synthesis followed by a sul-furization treatment. Powders and ceramics were characterised through various techniques (XRD, UV-Vis-IR spectroscopy, particle size analysis, SEM, Impulse Excitation Technique, microhardness and fracture toughness tests) to assess their purity, study their microstructure and determine their optical and mechanical properties. The study reports the first IR transmission spectra, Poisson's ratio, Young's and shear moduli and fracture toughness values of La2O2S polycrystalline ceramics. The ceramics showed transparency in the 2-11 mu m range and their mechanical performances were all superior to that of commercial infrared ceramics. The best trans-mission (89% of the theoretical transmission) was measured at 7.3 mu m for 1 mm-thick ceramics hot-pressed at 1200-1250 degrees C.

Due to the ageing of the population, the synthesis of biomaterials and the optimization of their physico-chemical characteristics are at the heart of many research projects in regenerative medicine. The emergence of 3D printing techniques has rapidly led to the manufacture PLA-BG composite scaffolds using the FFF (Fused Filament Fabrication) technique. However, this composite presents some problems including a lower mechanical strength than the two compounds alone, probably due to the ionic salting-out induced by the BG. This study aims to counter this phenomenon by coating the BG particles with a thin layer of gold. The 3D composite objects will then be characterized mechanically and biologically to ensure that the bioactive character of the composite is preserved.

NaGaS2 is a newly discovered compound that has already shown great promise for a variety of applications because of its layered structure and ion exchange properties. In this work, crystalline NaGaS2 has been synthesized by an alternative method to what has been previously published, namely, by mechanochemistry, either by a direct one-step process or by a two-step process. In the one-step process, crystalline NaGaS2 is directly formed by milling sodium sulfide Na2S and gallium(III) sulfide Ga2S3. However, an amorphous material is present in majority together with the crystalline phase. In the two-step process, amorphous NaGaS2 is first obtained by mechanical milling and then heated above its glass transition temperature to obtain a glass-ceramic mainly composed of crystalline NaGaS2. For the two-step process, changes of the local atomic-level structure in amorphous NaGaS2 and after crystallization were analyzed by high-field solid-state nuclear magnetic resonance (NMR) spectroscopy as well as by X-ray total scattering and pair distribution function (PDF) analysis. Based on quantitative analysis on the 23Na NMR spectra, modifying the annealing treatment can promote the formation of the crystalline phase up to a molar fraction of 83.8%.

In this work, an original way of shaping chalcogenide optical components has been investigated. Thorough evaluation of the properties of chalcogenide glasses before and after 3D printing has been carried out in order to determine the impact of the 3D additive manufacturing process on the material. In order to evaluate the potential of such additive glass manufacturing, several preliminary results obtained with various chalcogenide objects and components, such as cylinders, beads, drawing preforms and sensors, are described and discussed. This innovative 3D printing method opens the way for many applications involving chalcogenide fiber elaboration, but also many other chalcogenide glass optical devices.

In this paper, ferroelectric ceramics with (Sr2Ta2O7)(100)(-x)(La2Ti2O7)(x) (STLTO) compositions have been investigated and their dielectric properties have been characterized in wide frequency band (from few kHz to few GHz); their integration in Dielectric Resonator Antennas (DRA) was conducted. The dense STLTO ceramics have been obtained by high temperature sintering of powders synthetized by solid state chemistry route. STLTO crystalline cell parameters and volume vary linearly as a function of the chemical composition (x) thus demonstrating an ideal solid solution domain for 0 <= x <= 3. Dielectric characterizations highlight that the permittivity and the dielectric loss vary according to the composition (x) and that the lowest losses are obtained for x< 1.65 compositions. The latter corresponds to the transition between the ferroelectric and paraelectric compositions of the STLTO material at room temperature. A low profile DRA structure was realized using a cylindrical paraelectric STLTO resonator (with x = 0) with a permittivity of 83 and losses tan delta = 5 x 10(-3)@3.3 GHz. The DRA prototype was simulated, produced and tested. It exhibits a hybrid HEM11 delta mode, with a resonant frequency at 5.80 GHz, a 4.9% bandwidth and a gain of 6.4 dB. These features confirm the potential of the paraelectric STLTO compositions in compact antennas radiating at frequencies below 6 GHz. (C) 2021 Elsevier B.V. All rights reserved.

For several years, chalcogenide glasses have been studied as good candidates for numerous applications in the midinfrared region. Indeed, these glasses are transparent from 1 to 20 μm (depending on the composition), a mid- IR windows well-suited for sensing molecules whose optical signatures are located in the 2-16 μm range. In addition, thanks to appropriate thermal properties, chalcogenide glasses can be drawn into fibers, including microstructured optical fibers. In this work, a new method based on 3D-printing process is investigated to produce hollow chalcogenide glass preforms, which are then drawn into hollow-core fibers. The transmission of the “printed” hollow-core fiber has been measured and compared to the initial glass. A significant, but still manageable, increase by a factor of 2.5 is observed. This works opens a promising way for the fabrication of chalcogenide MOFs, more particularly for the elaboration of hollow core fibers.

Mn2+ doped Ca1-xSrxCN2 phosphors were synthesized by a solid-state reaction in only 1 h under NH3 atmosphere at 700 degrees C from doped calcium carbonate and carbon nitride as precursors. The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated in order to evaluate the potential of such systems as red phosphors. All pure and well-crystallized Mn2+ doped samples exhibit broad red emission around 680 nm when excited at 270 nm at room temperature corresponding to the T-4(1g)((4)G) -> (6)A(1g)(S-6) transition. Maximum emission in CaCN2: Mn is obtained for Mn2+ content of 4 %mol and is stable up to 343 K and then shows a 20% decrease at 393 K. Finally, the progressive substitution of Sr2+ for Ca2+ evidences a solid solution domain between CaCN2 and beta-SrCN2 with continuous increase of the crystal lattice dimensions. However, such substitution has no impact on the wavelength emission but leads to a decrease of the luminescence efficiency of the phosphor.