Search Results (19)

Multifunctional road marking coatings with the functions of high-temperature stability, degradation of exhaust gas, and self-cleaning are of great significance for the safe operation and environmental protection of tunnels. This article uses active acrylic resin and an organosilicon hydrophobic agent as the base material, selects expanded vermiculite and glass microspheres as insulation fillers, and uses ammonium polyphosphate, pentaerythritol, melamine, and aluminum hydroxide as high-thermal-stability systems to prepare a two-component road marking coating base material. Then, nano SiO₂ and modified nano TiO₂ are added as modifiers to prepare a multifunctional road marking coating for tunnels. The physical and chemical properties of multifunctional road marking coatings are evaluating based on laboratory tests including thermogravimetry and derivative thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, exhaust degradation, and contact angle tests. The results indicate that the developed multifunctional road marking coating effectively reduces the thermal conductivity of the carbon layer through physical changes in the flame retardant system and the heat resistance formed by the high breaking bond energy of nano SiO₂ during the combustion process. It forms a ceramic-like structure of titanium pyrophosphate with nano TiO₂ that is beneficial for improving flame retardancy without generating harmful volatile gases and has good flame retardant properties. N–V co-doping reduces the bandgap of TiO₂, broadens the absorption range of visible light by nano TiO₂, improves the catalytic efficiency of visible light, and achieves the degradation efficiency of the four harmful components NO_x, HC, CO, and CO₂ in automotive exhaust by 23.4%, 8.3%, 2.5%, and 2.9%, respectively. The solid–liquid phase separation in the multifunctional road marking coating in the tunnel causes the formation and accumulation of nano SiO₂ and TiO₂ particles on the coating surface, resulting in a microstructure similar to the “micro–nano micro-convex” on the lotus leaf surface and making a water droplet contact angle of 134.2° on the coating surface. Full article

An efficient quantum cutting mechanism was observed in a system comprising ${\mathrm{T}\mathrm{b}}^{3+}-{\mathrm{Y}\mathrm{b}}^{3+}$ codoped silica hafnia glass and glass-ceramic. Thin films were deposited on silicon substrates using the dip-coating method and photoluminescence dynamics revealed a quantum efficiency of up to 179% at 980 nm. These films can efficiently convert light to lower energy levels and can easily be integrated into silicon-based solar cells, increasing their photoelectric conversion efficiency at a low cost. This was demonstrated through electrical characterization, which revealed a boost in solar cell efficiency when the film was utilized. It was specifically noted that the efficiency of Si solar cells increased by 10.79% and 10.78% when covered with 70SiO₂$-$30HfO₂$-3{\mathrm{T}\mathrm{b}}^{3+}-12{\mathrm{Y}\mathrm{b}}^{3+}$ glass and glass ceramic, respectively. Furthermore, an evaluation of the additional external quantum efficiency, derived from this optical system, revealed an improvement ranging from 2.64% to 3.44%. This finding highlights the enhanced light conversion capabilities of the quantum cutting mechanism within the system. Full article

Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and niobium oxides and doped with cobalt ions were studied for the development of multifunctional transparent glass-ceramics. Initial glass and glass-ceramics obtained by isothermal heat-treatments at 700–900 °C contain YNbO₄ nanocrystals with the distorted tetragonal structure. In samples heated at 1000 °C and above, the monoclinic features are observed. High-temperature X-ray diffraction technique clarifies the mechanism of the monoclinic yttrium orthoniobate formation, which occurs not upon high-temperature heat-treatments above 900 °C but at cooling the glass-ceramics after such heat-treatments, when YNbO₄ nanocrystals with tetragonal structure undergo the second-order transformation at ~550 °C. Lithium aluminosilicate solid solutions (ss) with β-quartz structure are the main crystalline phase of glass-ceramics prepared in the temperature range of 800–1000 °C. These structural transformations are confirmed by Raman spectroscopy and illustrated by SEM study. The absorption spectrum of the material changes only with crystallization of the β-quartz ss due to entering the Co²⁺ ions into this phase mainly in octahedral coordination, substituting for Li⁺ ions. At the crystallization temperature of 1000 °C, the Co²⁺ coordination in the β-quartz solid solutions changes to tetrahedral one. Transparent glass-ceramics have a thermal expansion coefficient of about 10 × 10⁻⁷ K⁻¹. Full article

With the rapid development of microelectronic information technology, microelectronic packaging has higher requirements in terms of integration density, signal transmission speed, and passive component integration. Low temperature co-fired ceramics (LTCC) exhibit excellent dielectric properties and low temperature sintering properties, which meets the above-mentioned requirements. This work investigates the effects of CaF₂ doping (0–16 mol%) on the glass structure, sintering behavior, crystallization, microstructure, and microwave dielectric properties of the CaO-B₂O₃-SiO₂ (CBS) glass-ceramic system. Glass-ceramics were prepared using the conventional melting and quenching method. The physical and chemical properties of the glass-ceramics were analyzed using various techniques including TMA, SDT, FTIR, XRD, SEM, and a network analyzer. The results indicate that CaF₂ doping can effectively reduce the sintering temperature and softening temperature of CBS ceramics. It also substantially improves the densification, dielectric, and mechanical properties. The appropriate amount of CaF₂-doped CBS glass-ceramics can be sintered below 800 °C with a low dielectric constant and loss at high frequency (ε_r < 6, tanδ < 0.02 @ 10~13 GHz). Specifically, 8 mol% CaF₂ doped CBS glass-ceramics sintered at 790 °C exhibit excellent microwave dielectric and thermal properties, with ε_r ~ 5.92 @ 11.4 GHz, tanδ ~ 1.59 × 10⁻³, CTE ~ 7.76 × 10⁻⁶/°C, λ ~ 2.17 W/(m·k), which are attractive for LTCC applications. Full article

Ultra-broadband emission in the range of 1.0–2.1 mm is required in medicine (OCT), metrology, and sensing systems. Novel ideas are connected to the rare-earth co-doping of low-phonon energy glasses (further fiber core) and ultra-broad emissions obtained as a result of the superposition of particular luminescence bands. The 1.5–2 um broadband ASE in both germanate glasses and glass fibers co-doped with Tm³⁺/Ho³⁺, Yb³⁺/Tm³⁺/Ho³⁺ and Er³⁺/Tm³⁺/Ho³⁺ can be realized as a result of radiative transitions in the 1.4–2.1 mm range due to Tm³⁺: ³H₄→³F₄ (1.45 mm), Er³⁺: ⁴I_13/2→⁴I_15/2 (1.55 mm), Tm³⁺: ³F₄→³H₆ (1.8 mm), and Ho³⁺: ⁵I₈→⁵I₇ (1.55 mm) transitions and the partial donor–acceptor energy transfer and superposition of the particular emission bands. This work presents two important issues: (1) the optimization of the co-dopant concentration in germanate glasses and the construction of double-clad, multicore fibers to obtain flat broadband emission in the 1.5–2.1 mm range; (2) the development of the multicore glass–ceramic optical fibers co-doped with rare-earth and d-block metals, which enables the extension of the emission band. The effect of the rare-earth concentration on the donor–acceptor energy transfer and, finally, obtaining broadband luminescence in glasses co-doped with Er³⁺/Tm³⁺/Ho³⁺, Yb³⁺/Tm³⁺/Ho³⁺ and glass–ceramics co-doped with Ni²⁺/Er³⁺ will be presented. Constructions of the multicore characterized by broadband, eye-safe ASE will be also analyzed. Full article

In this study, a set of ZnO-based thin films were prepared on glass substrates at various substrate temperatures via the direct current magnetron sputtering of ceramic targets with the following compositions: pure ZnO, Al-doped ZnO with doping levels of 1 and 2 at.%, Ga-doped ZnO with doping levels of 1 and 2 at.%, and (Al, Ga)-co-doped ZnO with doping levels of 1 and 2 at.% for each impurity metal. The dependencies of sheet resistance, carrier concentration, and Hall mobility on the substrate temperature were studied for the deposited films. The results of evaluating the electrical performances of the films were compared with the data of their XRD study. According to the XRD data, among all the deposited ZnO films, the maximum crystallinity was found in the co-doped thin film with doping levels of 2 at.% for each impurity metal, deposited at a substrate temperature of 300 °C. It was revealed that the observed increase in the Hall mobility and carrier concentration for the co-doped films may, in particular, be due to the difference in the preferred localization of Ga and Al impurities in the ZnO film: the Ga ions were mainly incorporated into the crystal lattice of ZnO nanocrystallites, while the Al impurity was mostly localized in the intercrystalline space at the grain boundaries. Full article

Glass-ceramic is semi-novel material with many applications, but it is still problematic in obtaining fibers. This paper aims to develop a new glass-ceramic material that is a compromise between crystallization, thermal stability, and optical properties required for optical fiber technology. This compromise is made possible by an alternative method with a controlled crystallization process and a suitable choice of the chemical composition of the core material. In this way, the annealing process is eliminated, and the core material adopts a glass-ceramic character with high transparency directly in the drawing process. In the experiment, low phonon antimony-germanate-silicate glass (SGS) doped with Eu³⁺ ions and different concentrations of P₂O₅ were fabricated. The glass material crystallized during the cooling process under conditions similar to the drawing processes’. Thermal stability (DSC), X-ray photo analysis (XRD), and spectroscopic were measured. Eu³⁺ ions were used as spectral probes to determine the effect of P₂O₅ on the asymmetry ratio for the selected transitions (⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂). From the measurements, it was observed that the material produced exhibited amorphous or glass-ceramic properties, strongly dependent on the nucleator concentration. In addition, the conducted study confirmed that europium ions co-form the EuPO₄ structure during the cooling process from 730 °C to room temperature. Moreover, the asymmetry ratio was changed from over 4 to under 1. The result obtained confirms that the developed material has properties typical of transparent glass-ceramic while maintaining high thermal stability, which will enable the fabrication of fibers with the glass-ceramic core. Full article

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

Knowing the temperature distribution within the conducting walls of various multilayer-type materials is crucial for a better understanding of heat-transfer processes. This applies to many engineering fields, good examples being photovoltaics and microelectronics. In this work we present a novel fluorescence technique that makes possible the non-invasive imaging of local temperature distributions within a transparent, temperature-sensitive, co-doped Er:GPF1Yb0.5Er glass-ceramic with micrometer spatial resolution. The thermal imaging was performed with a high-resolution fluorescence microscopy system, measuring different focal planes along the z-axis. This ultimately enabled a precise axial reconstruction of the temperature distribution across a 500-µm-thick glass-ceramic sample. The experimental measurements showed good agreement with computer-modeled heat simulations and suggest that the technique could be adopted for the spatial analyses of local thermal processes within optically transparent materials. For instance, the technique could be used to measure the temperature distribution of intermediate, transparent layers of novel ultra-high-efficiency solar cells at the micron and sub-micron levels. Full article

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⁺ (⁵D₄ → ⁷F_J (J = 6–3)) and Eu³⁺ (⁵D₀ → ⁷F_J (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

An investigation of the structural and luminescent properties of the transparent germanate glass-ceramics co-doped with Ni²⁺/Er³⁺ for near-infrared optical fiber applications was presented. Modification of germanate glasses with 10–20 ZnO (mol.%) was focused to propose the additional heat treatment process controlled at 650 °C to obtain transparent glass-ceramics. The formation of 11 nm ZnGa₂O₄ nanocrystals was confirmed by the X-ray diffraction (XRD) method. It followed the glass network changes analyzed in detail (MIR—Mid Infrared spectroscopy) with an increasing heating time of precursor glass. The broadband 1000–1650 nm luminescence (λ_exc = 808 nm) was obtained as a result of Ni²⁺: ³T₂(³F) → ³A₂(³F) octahedral Ni²⁺ ions and Er³⁺: ⁴I_13/2 → ⁴I_15/2 radiative transitions and energy transfer from Ni²⁺ to Er³⁺ with the efficiency of 19%. Elaborated glass–nanocrystalline material is a very promising candidate for use as a core of broadband luminescence optical fibers. Full article

Zirconia repair could be a feasible alternative option to total replacement in fractured zirconia-based restorations. Maximising the bond strength by enriching zirconia with fluorapatite glass-ceramics (FGC) powder has been addressed and compared to other surface treatments. Besides resin composite, other repair materials have been proposed and compared. Zirconia blocks received different surface treatments (A—sandblasting with tribochemical silica-coated alumina (CoJet). B—sandblasting with FGC powder (FGC), C—fluorapatite glass-ceramic coat+ neodymium-doped yttrium aluminum garnet laser irradiation (FGC + Nd: YAG), and D—no surface treatment). The surface roughness, topography, and crystallinity were investigated by a profilometer, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses, respectively. For each surface treatment, three repair materials (feldspathic porcelain, lithium disilicate, and resin composite) were bonded to zirconia with 10, Methacryloyloxydecyl dihydrogen phosphate (MDP)–Monobond Plus/ Multilink Automix. Bonded specimens were thermocycled for 10,000 cycles and tested for shear bond strength (SBS) at a speed of 1 mm/min, followed by the analysis of the mode of failure. FGC + Nd: YAG laser group reported the highest surface roughness and monoclinic content compared to CoJet, FGC, and control groups. The highest mean SBS was found in FGC-blasted zirconia, followed by FGC + Nd: YAG laser and CoJet treated groups. However, the lowest SBS was found in control groups regardless of the repair material. Sandblasting zirconia with FGC powder increased SBS of resin to zirconia with lower monoclinic phase transformation compared to FGC + Nd: YAG or CoJet groups. Full article

In this work, the series of Tb³⁺/Eu³⁺ co-doped xerogels and derivative glass-ceramics containing CaF₂ nanocrystals were prepared and characterized. The in situ formation of fluoride crystals was verified by an X-ray diffraction technique (XRD) and transmission electron microscopy (TEM). The studies of the Tb³⁺/Eu³⁺ energy transfer (ET) process were performed based on excitation and emission spectra along with luminescence decay analysis. According to emission spectra recorded under near-ultraviolet (NUV) excitation (351 nm, ⁷F₆ → ⁵L₉ transition of Tb³⁺), the mutual coexistence of the ⁵D₄ → ⁷F_J (J = 6–3) (Tb³⁺) and the ⁵D₀ → ⁷F_J (J = 0–4) (Eu³⁺) luminescence bands was clearly observed. The co-doping also resulted in gradual shortening of a lifetime from the ⁵D₄ state of Tb³⁺ ions, and the ET efficiencies were varied from η_ET = 11.9% (Tb³⁺:Eu³⁺ = 1:0.5) to η_ET = 22.9% (Tb³⁺:Eu³⁺ = 1:2) for xerogels, and from η_ET = 25.7% (Tb³⁺:Eu³⁺ = 1:0.5) up to η_ET = 67.4% (Tb³⁺:Eu³⁺ = 1:2) for glass-ceramics. Performed decay analysis from the ⁵D₀ (Eu³⁺) and the ⁵D₄ (Tb³⁺) state revealed a correlation with the change in Tb³⁺–Eu³⁺ and Eu³⁺–Eu³⁺ interionic distances resulting from both the variable Tb³⁺:Eu³⁺ molar ratio and their partial segregation in CaF₂ nanophase. Full article

This study aims to examine the studies regarding In doped ZnO published in the Web of Science database. A total of 777 articles were reached (31 March 2020). The articles were downloaded for the bibliometric analysis and collected in a file. The file was uploaded to VOSViewer programme in order to reveal the most used keywords, words in the abstracts, citation analyses, co-citation and co-authorship and countries analyses of the articles. The results showed that the most used keywords were “ZnO”, “photoluminescence”, “optical properties”, “thin films” and “doping”. These results indicate that the articles mostly focus on some characteristics of In doped ZnO thin films such as structural, optical and electrical features. When the distribution of the number of articles using the keywords by year was searched, it was found that recent articles focus mainly on synthesis of In doped ZnO film via chemical routes such as sol-gel and hydrothermal syntheses, and on ZnO-based device applications such as solar cells and gas sensors. The most used keywords were also found to be films, X-ray, glass substrate, X-ray Diffraction (XRD), spectra and layer. These results indicate that the studies mostly focus on In doped ZnO thin films as transparent conductive oxide (TCO) material used in device applications like solar cells. In this context, it was found that structural, topographical, optical, electrical and magnetic properties of In doped ZnO films were characterized in terms of defected structure or defect type, substrate temperature, film thickness and In doping content. When the distribution of these words is shown on a year-by-year basis, it is evident that more recent articles tend to focus both on efficiency and performance of In doped ZnO films as TCO in solar cells, diodes and photoluminescence applications both on nanostructures, such as nanoparticles, and nanorods for gas sensor applications. The results also indicated that Maldonado and Asomoza were the most cited authors in this field. In addition, Major, Minami and Ozgur were the most cited (co-citation) authors in this field. The most cited journals were found to be Thin Solid Films, Journal of Materials Science Materials in Electronics and Journal of Applied Physics and, more recently, Energy, Ceramics International, Applied Physics-A, Optik, Material Research Express, ACS Applied Materials and Interfaces and Optical Materials. The most co-cited journals were Applied Physics Letters, Thin Solid Films, Journal of Applied Physics, Physical Review B, and Applied Surface Science. Lastly, the countries with the highest number of documents were China, India, South Korea, USA and Japan. Consequently, it is suggested that future research needs to focus more on synthesis and characterization with different growth techniques which make In doped ZnO suitable for device applications, such as solar cells and diodes. In this context, this study may provide valuable information to researchers for future studies on the topic. Full article

The optical photoluminescent (PL) emission of Yb³⁺ ions in the near infrared (NIR) spectral region at about 950–1100 nm has many potential applications, from photovoltaics to lasers and visual devices. However, due to their simple energy-level structure, Yb³⁺ ions cannot directly absorb UV or visible light, putting serious limits on their use as light emitters. In this paper we describe a broadband and efficient strategy for sensitizing Yb³⁺ ions by Ag codoping, resulting in a strong 980 nm PL emission under UV and violet-blue light excitation. Yb-doped silica–zirconia–soda glass–ceramic films were synthesized by sol-gel and dip-coating, followed by annealing at 1000 °C. Ag was then introduced by ion-exchange in a molten salt bath for 1 h at 350 °C. Different post-exchange annealing temperatures for 1 h in air at 380 °C and 430 °C were compared to investigate the possibility of migration/aggregation of the metal ions. Studies of composition showed about 1–2 wt% Ag in the exchanged samples, not modified by annealing. Structural analysis reported the stabilization of cubic zirconia by Yb-doping. Optical measurements showed that, in particular for the highest annealing temperature of 430 °C, the potential improvement of the material’s quality, which would increase the PL emission, is less relevant than Ag-aggregation, which decreases the sensitizers number, resulting in a net reduction of the PL intensity. However, all the Ag-exchanged samples showed a broadband Yb³⁺ sensitization by energy transfer from Ag aggregates, clearly attested by a broad photoluminescence excitation spectra after Ag-exchange, paving the way for applications in various fields, such as solar cells and NIR-emitting devices. Full article