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[EN] Electrochromic devices (ECDs) have the ability to selectively change color under the influence of electric current or potential and can keep the selected color after disconnection. They are used as smart windows, e-ink displays and even as flexible tapes. Most multicolor ECDs incorporate traditional “sandwich” architecture, which requires at least one electrode to be made of a transparent conductive polymer or thin film ceramics, and can be quite fragile and sensitive. In this paper, a flexible and durable multicolor ECD tape is reported, which uses advanced architecture, steel foil electrodes, and multiple coloration systems, for example intercalation used in tungsten and vanadium oxide based electrochromic systems, as well as a redox dye, for example methyl orange. The presented ECD tapes can utilize different metal oxides and color mechanisms with coloration efficiency around 10 cm2 C−1 for V2O5 and WO3 in both visible and IR range, and more than 30 cm2 C−1 for ZnO with added methyl orange dye. Due to the use of stainless-steel foil as a substrate, the assembled ECD tape has excellent durability properties, withstanding more than 39 MPa of pressure, and could therefore be used even in the most adverse conditions, for applications such as adaptive camouflage, color changing clothes, or other applications

Nd3+-doped, LaF3-based, transparent oxyfluoride glass-ceramics (GCs) containing Ag nanoparticles (NPs) have been prepared by a melt-quenching method. Different Ag-containing precursors were employed, with AgNO3 as the most suitable for obtaining Ag NPs segregated in the glassy matrix. Transmission electron microscopy and X-ray absorption spectroscopy determined the presence of Ag0 NPs, with higher concentrations in glass-ceramics produced in an inert atmosphere (N2). The spectral features of emission and excitation spectra, in addition to the different lifetimes of the 4 F3/2 state in the co-doped samples with Ag NPs, demonstrate the incorporation of Nd3+ ions into the LaF3 nanocrystals. The relative contribution to the emission from Nd3+ in the nanocrystals depends on the Ag concentration and atmosphere. The glass-ceramic co-doped with 0.2 wt% Ag, thermally treated in N2, exhibits the highest contribution of emissions attributable to Nd3+ ions in the crystalline phase. The crystalline fraction is similar to that of a Ag-free sample synthesized under analogous conditions. This increase of the luminescence is likely attributable to the enhancement of the local electric field in the LaF3 nanocrystals due to the presence of Ag0 NPs.

Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long w

This article seeks to explore the construction of bonds, their relation with the development of autonomy and the mental health problems of young adult ex-combatants of armed groups who are part of the reintegration process in Colombia. A total of 3977 records of the Psychosocial Multimodal Questionnaire (PMS) corresponding to young adults between 18 and 24 years old, which were applied in the development of the reincorporation process, were analyzed. Two complementary statistical analysis methods were applied: The Principal Components Method (PCA) and an agglomerative Hierarchical method. In the analysis of bonding processes, it was found that, in one group, about 80% of the cases recorded having experienced significant bonding ruptures due to violence, early abandonment and/or living in contexts of conflict and violence. Regarding the analysis of the processes of autonomy, a group corresponding to 70% reported not having the capacities to guarantee their autonomy and quality of life, going through conditions of job insecurity with the risk of incurring in criminal networks. And 39% report a high risk disposition in their relationship and autonomy processes., Este artículo busca explorar la construcción de los vínculos, su relación con el desarrollo de la autonomía y las problemáticas de salud mental de adultos jóvenes excombatientes de grupos armados que hacen parte del proceso de reintegración en Colombia. Se analizaron 3977 registros de la Encuesta Multimodal Psicosocial (EMP) correspondientes a adultos jóvenes entre los 18 y 24 años, que fueron aplicadas en desarrollo del proceso de reincorporación. Se aplicaron dos métodos de análisis estadísticos complementarios: el método de Componentes Principales (ACP) y un método Jerárquico aglomerativo. En el análisis de los procesos vinculares se encontró que en un grupo alrededor de un 80 % de los casos registra haber experimentado rupturas vinculares importantes a causa de la violencia, el abandono temprano y/o vivir en contextos de conflicto y violencia. En cuanto al análisis de los procesos de autonomía, se encontró que un grupo correspondiente al 70 % reporta no contar con las capacidades para garantizar su autonomía y calidad de vida, pasando por condiciones de precarización laboral con riesgo a incurrir en redes de delincuencia. Y un 39 % reporta coincidir alta disposición de riesgo en sus procesos vinculares y de autonomía.

Transparent oxyfluoride glass-ceramics doped with rare earth ions (RE3+) are promising materials for photoluminescence up- and down-conversion. In this study, glass compositions within the system 40SiO2–25Al2O3–18Li2O–7LiF–10YF3 (mol.%) doped with ErF3 and codoped with ErF3/YbF3 were prepared by melt-quenching method and subjected to thermal treatment at temperatures above glass transition (Tg + 35 °C) for long dwell times to obtain the corresponding glass-ceramics. The formation of LiYF4 and LiAlSiO4 nanocrystals was confirmed by XRD analysis after thermal treatment at 540 °C for 20 h. The increase in the treatment time up to 80 h resulted in the enhancement of the UC luminescence yield and the decrease of the Red to Green ratio (R/G) emission intensity. Due to the nano-sized crystals, the glass-ceramic products were transparent (%T) in near-infrared (NIR) and visible spectral region with %T remaining approximately 85% and 75%, respectively, after 20 h treatment. However, the visible window transparency reduced, with %T dropping to around 50% after 80 h due to the increase in crystal size and crystalline fraction. The influence of Yb3+ co-doping on the up-conversion (UC) luminescence has been investigated in the glass-ceramics and compared to the parent glasses, confirming that Yb3+ ions were also a key factor for facilitating up-conversion via energy transfer (ET), leading to a greater luminescence yield than for Er3+ single doped glass-ceramics and tuning of R/G intensities.

Transparent oxyfluoride glass-ceramic (OxGCs) coatings with composition 1.2Nd3+ 80SiO2- 20LaF3 were prepared following a sol-gel route labelled “pre-crystallized nanoparticles route”. OxGCs are transparent materials composed by one or more fluoride nanocrystals in a glass matrix. OxGCs have been prepared by sol-gel with encouraging results in powders and bulk glass-ceramics but not in coatings. In the present work, aqueous suspensions of LaF3 nanoparticles doped with Nd3+ were prepared by chemical route and then incorporated into a silica sol to obtain 1.2Nd3+ doped-80SiO2-20LaF3 particulate sols. Nd3+-LaF3 suspensions are characterized by XRD, HRTEM, and XRF revealing the presence of LaF3 as the unique crystalline phase. Then, 1.2Nd3+ -80SiO2-20LaF3 coatings were prepared by dip-coating and characterized by XRD, FTIR, and Ellipsometry. Photoluminescence measurements were performed for LaF3 nanoparticles and OxGCs coatings, confirming the presence of Nd3+ in the nanocrystals and showing well-structured crystalline-like emission spectra with lifetimes of 520 and 440 µs respectively.

Sm3+-doped and Sm3+/Dy3+ codoped SiO2–SrO–MgO glasses were prepared by conventional melt quenching and Sr2MgSi2O7 based glass–ceramics from sintering and crystallization of the glass powders. The thermal, structural, and optical properties of the glasses and glass–ceramics were investigated as a function of the dopant concentration. The optical characterization includes the photoluminescence spectra and the lifetimes of the 4G5/2 (Sm3+) and 4F9/2 (Dy3+) excited states. In Sm3+ single-doped samples, the emission intensity increases up to a concentration of 0.3 mol% Sm3+ ions and then decreases due to nonradiative energy transfer processes. The emission spectra in the glass–ceramics show a more resolved structure and higher intensity compared to the glass samples, suggesting a different and crystalline environment for the Sm3+ ions. The non-radiative processes also influence the experimental decays of the glass samples which deviate from a single exponential with lifetimes decreasing as Sm3+ concentration increases. The emission and excitation spectra of the codoped samples do not show significant energy transfer between Sm3+ and Dy3+ ions. Different emitting colors can be obtained in the codoped glasses by changing the excitation wavelength. The studied glass–ceramics could be applied as enamels on ceramic or metallic substrates.

Oxyfluoride glass-ceramics (OxGCs) with the molar composition 80SiO2-20(1.5Eu3+: NaGdF4) were prepared with sol-gel following the “pre-crystallised nanoparticles route” with promising optical results. The preparation of 1.5 mol % Eu3+-doped NaGdF4 nanoparticles, named 1.5Eu3+: NaGdF4, was optimised and characterised using XRD, FTIR and HRTEM. The structural characterisation of 80SiO2-20(1.5Eu3+: NaGdF4) OxGCs prepared from these nanoparticles’ suspension was performed by XRD and FTIR revealing the presence of hexagonal and orthorhombic NaGdF4 crystalline phases. The optical properties of both nanoparticles’ phases and the related OxGCs were studied by measuring the emission and excitation spectra together with the lifetimes of the 5D0 state. The emission spectra obtained by exciting the Eu3+-O2− charge transfer band showed similar features in both cases corresponding the higher emission intensity to the 5D0→7F2 transition that indicates a non-centrosymmetric site for Eu3+ ions. Moreover, time-resolved fluorescence line-narrowed emission spectra were performed at a low temperature in OxGCs to obtain information about the site symmetry of Eu3+ in this matrix. The results show that this processing method is promising for preparing transparent OxGCs coatings for photonic applications.

Transparent oxyfluoride glass-ceramic (OxGCs) coatings with composition 1.2Nd3+ 80SiO2- 20LaF3 were prepared following a sol-gel route labelled “pre-crystallized nanoparticles route”. OxGCs are transparent materials composed by one or more fluoride nanocrystals in a glass matrix. OxGCs have been prepared by sol-gel with encouraging results in powders and bulk glass-ceramics but not in coatings. In the present work, aqueous suspensions of LaF3 nanoparticles doped with Nd3+ were prepared by chemical route and then incorporated into a silica sol to obtain 1.2Nd3+ doped-80SiO2-20LaF3 particulate sols. Nd3+-LaF3 suspensions are characterized by XRD, HRTEM, and XRF revealing the presence of LaF3 as the unique crystalline phase. Then, 1.2Nd3+ -80SiO2-20LaF3 coatings were prepared by dip-coating and characterized by XRD, FTIR, and Ellipsometry. Photoluminescence measurements were performed for LaF3 nanoparticles and OxGCs coatings, confirming the presence of Nd3+ in the nanocrystals and showing well-structured crystalline-like emission spectra with lifetimes of 520 and 440 µs respectively.

Sm3+-doped and Sm3+/Dy3+ codoped SiO2–SrO–MgO glasses were prepared by conventional melt quenching and Sr2MgSi2O7 based glass–ceramics from sintering and crystallization of the glass powders. The thermal, structural, and optical properties of the glasses and glass–ceramics were investigated as a function of the dopant concentration. The optical characterization includes the photoluminescence spectra and the lifetimes of the 4G5/2 (Sm3+) and 4F9/2 (Dy3+) excited states. In Sm3+ single-doped samples, the emission intensity increases up to a concentration of 0.3 mol% Sm3+ ions and then decreases due to nonradiative energy transfer processes. The emission spectra in the glass–ceramics show a more resolved structure and higher intensity compared to the glass samples, suggesting a different and crystalline environment for the Sm3+ ions. The non-radiative processes also influence the experimental decays of the glass samples which deviate from a single exponential with lifetimes decreasing as Sm3+ concentration increases. The emission and excitation spectra of the codoped samples do not show significant energy transfer between Sm3+ and Dy3+ ions. Different emitting colors can be obtained in the codoped glasses by changing the excitation wavelength. The studied glass–ceramics could be applied as enamels on ceramic or metallic substrates.

Oxyfluoride glass-ceramics (OxGCs) with the molar composition 80SiO2-20(1.5Eu3+: NaGdF4) were prepared with sol-gel following the “pre-crystallised nanoparticles route” with promising optical results. The preparation of 1.5 mol % Eu3+-doped NaGdF4 nanoparticles, named 1.5Eu3+: NaGdF4, was optimised and characterised using XRD, FTIR and HRTEM. The structural characterisation of 80SiO2-20(1.5Eu3+: NaGdF4) OxGCs prepared from these nanoparticles’ suspension was performed by XRD and FTIR revealing the presence of hexagonal and orthorhombic NaGdF4 crystalline phases. The optical properties of both nanoparticles’ phases and the related OxGCs were studied by measuring the emission and excitation spectra together with the lifetimes of the 5D0 state. The emission spectra obtained by exciting the Eu3+-O2− charge transfer band showed similar features in both cases corresponding the higher emission intensity to the 5D0→7F2 transition that indicates a non-centrosymmetric site for Eu3+ ions. Moreover, time-resolved fluorescence line-narrowed emission spectra were performed at a low temperature in OxGCs to obtain information about the site symmetry of Eu3+ in this matrix. The results show that this processing method is promising for preparing transparent OxGCs coatings for photonic applications.

Tuning color output and enhancing upconversion emission of Er3+ ions in transparent sodium lutetium fluoride glassceramics in bulk and optical fibers, by adjusting the Yb3+ doping level and the excitation power, has been demonstrated. The addition of Yb3+ enhances the UC emission and tunes the color from green to yellow due to an increase of the red-to-green intensity ratio. Moreover, the relative emission intensities of blue, green, and red emissions can be changed by controlling the excitation power which tunes the color from yellow to green.

The mechanical qualities of AZ31B magnesium alloys make them a promising material for biodegradable metallic implants. However, rapid degradation limits the application of these alloys. In the present study, 58S bioactive glasses were synthesized using the sol-gel method and several polyols such as glycerol, ethylene glycol, and polyethylene glycol, were used to improve the sol stability and to control the degradation of AZ31B. The synthesized bioactive sols were dip-coated onto AZ31B substrates and then, characterized by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical techniques (potentiodynamic and electrochemical impedance spectroscopy), among them. FTIR analysis confirmed the formation of a silica, calcium, and phosphate system and the XRD the amorphous nature of the 58S bioactive coatings obtained by sol-gel. The contact angle measurements confirmed that all the coatings were hydrophilic. The biodegradability response under physiological conditions (Hank's solution) was investigated for all the 58S bioactive glass coatings, observing a different behaviour depending on the polyols incorporated. Thus, for 58S PEG coating, an efficient control of the release of H2 gas was observed, and showing a pH control between 7.6 and 7.8 during all the tests. A marked apatite precipitation was also observed on the surface of the 58S PEG coating after the immersion test. Thus, the 58S PEG sol-gel coating is considered a promising alternative for biodegradable magnesium alloy-based medical implants.

[EN] The influence of Al2O3 addition on the precipitation of NaYF4 crystals in oxyfluoride glasses has been investigated through the thermal, structural, and optical characterization of the parent glasses and corresponding glass–ceramics (GCs). The high-resolution transmission electron microscopy analysis of the GC with 5 mol% of Al2O3 shows the presence of phase-separated droplets about 69 nm in size containing several NaYF4 nanocrystals with the diameter of about 10–15 nm. Raman and magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy were used to examine the structural changes attributed to the addition of Al2O3. The 19F MAS-NMR analysis indicated that fluorine atoms are present in different chemical environments (Na–F, Na–Si–F, Na–Al–F, and NaYF4). The increasing amount of Al2O3 reduces the crystallization of NaYF4 phase due to the increased fraction of fluorine bound in Na–Al–F environments. The visible luminescence investigation of the glasses and GCs demonstrated that the intensity of Er3+ ions emission transitions in the GCs was higher than that of the parent glass. This difference was attributed to the presence of Er3+ ions bound in NaYF4 crystalline phase. Further evidence that the Er3+ ions were present in NaYF4 phase was provided by the fact that the excited level Er3+:4S3/2 lifetime was increased in GCs as compared to parent glass.

[EN] In this work five independent pre-treatments – mechanical polishing, alkaline and acid etching, sol-gel primer, and anodizing – were applied on mild steel and aluminum (AA7075 and AA2024) substrates before the deposition of epoxy coatings. The results demonstrate that efficient adhesion can be achieved by simple methodologies and widely available chemicals as an alternative to toxic conversion layers or highly energetic processes. All the treatments provided higher adhesion (up to 75%, 61% and 14% on AA7075, AA2024 and steel, respectively) and better anti-corrosion performance (increase of impedance values at low frequency up to four orders of magnitude) than the polished reference. The anodizing of aluminum alloys yielded good anti-corrosion performance, but slightly lower mechanical properties compared to sol-gel primer and alkaline etching. The hydroxyls density was found to play a major role in strong adhesion prevailing over surface roughness, contact area, oxide thickness and hydrophobicity. Despite the efficient performance of hydrogen bonds from acid and alkaline etching on aluminum, these connections do not yield sufficiently stable bonds that make an impermeable barrier of epoxy coatings on steel. Covalent bonds (Me-O-Si) represent the key to achieve a significant improvement in mechanical and chemical resistance against the ingress of water and polymer chain relaxation. This makes the sol-gel primer a simple, economical, and environmentally alternative towards efficient bonding at a molecular level.

[EN] Electrochromic devices (ECDs) have the ability to show color even when electrical power is disconnected. However, challenges such as simple and cost-effective electrochromic material preparation, insufficient coloration, slow switching times, and poor cycling stability have yet to be overcome. The paper describes an electrochromic device with WO3 thin film as the electrochromic material for the working electrode and ZnO thin film as a counter electrode fabricated on FTO glass substrates by a simple sol–gel spin coating method. The optical contrast at 600 nm of ZnO counter electrode based ECD (12.4%) is almost double that of graphite counter electrode based ECD (6.5%), showing higher efficiency and better electrochromic response. The properties of ECD devices were also examined using cyclic voltammetry and chronoamperometry measurements with results showing that the devices were stable and the charge required to tint the device (5.6 mA s) is reduced compared to typical graphite-coated counter electrode. These types of devices are promissing candidates to be used as smart windows., [ES] Los dispositivos electrocrómicos (ECD) tienen la capacidad de mostrar color incluso cuando se desconectan de la energía eléctrica. Sin embargo, para su implantación total deben superarse importantes desafíos como la preparación de materiales electrocrómicos simples y rentables, la coloración insuficiente, los tiempos de conmutación que son lentos y la mala estabilidad del ciclo. En este artículo se describe la preparación de un dispositivo electrocrómico basado en una película delgada de WO3 como electrodo de trabajo y una película delgada de ZnO obtenida por sol-gel como contra-electrodo, todo fabricado sobre sustratos de vidrio FTO mediante un método simple de centrifugado. Como resultados destacar que el contraste óptico a 600 nm del ECD basado en el contra-electrodo de ZnO (12,4%) es casi el doble que el del sistema ECD basado en el contra-electro de grafito (6,5%), mostrando una mayor eficiencia y una mejor respuesta electrocrómica. Las propiedades del dispositivo ECD de ZnO también se examinaron mediante voltametría cíclica y cronoamperometría y los resultados mostraron que los dispositivos eran estables y la carga necesaria para teñir el dispositivo (5,6 mAs) se reducía comparado con el dispositivo ECD de grafito. Este tipo de dispositivos son candidatos prometedores para ser utilizados como ventanas inteligentes.

Transparent oxyfluoride glass-ceramics doped with rare earth ions (RE3+) are promising materials for photoluminescence up- and down-conversion. In this study, glass compositions within the system 40SiO2–25Al2O3–18Li2O–7LiF–10YF3 (mol.%) doped with ErF3 and codoped with ErF3/YbF3 were prepared by melt-quenching method and subjected to thermal treatment at temperatures above glass transition (Tg + 35 °C) for long dwell times to obtain the corresponding glass-ceramics. The formation of LiYF4 and LiAlSiO4 nanocrystals was confirmed by XRD analysis after thermal treatment at 540 °C for 20 h. The increase in the treatment time up to 80 h resulted in the enhancement of the UC luminescence yield and the decrease of the Red to Green ratio (R/G) emission intensity. Due to the nano-sized crystals, the glass-ceramic products were transparent (%T) in near-infrared (NIR) and visible spectral region with %T remaining approximately 85% and 75%, respectively, after 20 h treatment. However, the visible window transparency reduced, with %T dropping to around 50% after 80 h due to the increase in crystal size and crystalline fraction. The influence of Yb3+ co-doping on the up-conversion (UC) luminescence has been investigated in the glass-ceramics and compared to the parent glasses, confirming that Yb3+ ions were also a key factor for facilitating up-conversion via energy transfer (ET), leading to a greater luminescence yield than for Er3+ single doped glass-ceramics and tuning of R/G intensities.

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.

[EN] Transparent oxyfluoride glass-ceramics (GCs) containing KLaF4 nanocrystals (NCs) doped with Nd3+ were prepared by Spark Plasma Sintering (SPS). Glass powder pellets were sintered under a vacuum atmosphere, optimizing the processing parameters such as particle size, pressure, temperature, and holding time to obtain full densification. Transparency decreased when decreasing the particle size due to higher carbon contamination from the die. The alpha-KLaF4 crystalline phase was identified by X-ray diffraction (XRD) and its average crystal size was 10-20 nm. High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of KLaF4 nanocrystals with incorporated Nd3+ ions. Low-temperature site-selective emission and excitation spectra of Nd3+ ions confirmed that alpha-KLaF(4 )was the predominant polymorph, although a minor presence of beta- KLaF4 was also demonstrated.

Oxyfluoride glass-ceramics (OxGCs) are transparent materials composed by an oxide glass matrix with homogeneously distributed fluoride nanocrystals. In particular, OxGCs with RE-doped lanthanide-fluoride nanocrystals are of special interest for photonic applications. More than 600 publications including several review papers were indexed on Scopus related to “glass-ceramics” revealing the importance of the topic. Melt-quenching followed by thermal treatment, is the most used preparation method, which allows materials in bulk and fibre form to be obtained, being also a scalable industrial process. Spark plasma sintering from glass powders is showing promising results. The sol-gel process has appeared as an alternative method to avoid some of the drawbacks of the melting process such as the high temperature. It also permits to process materials with different shapes such as thin films, nano-sized powders or bulk materials at very low temperature. This paper reviews the different aspects involved in the preparation of OxGC materials by melt-quenching, spark plasma sintering and sol-gel and how the processing parameters directly affect the glass-ceramics properties from results of the GlaSS research group from CSIC. A comparison of the thermal, structural and optical properties is discussed along with some perspectives for preparing other advanced materials within this field.

[EN] In the present work, a study was carried out to compare the morphology and electrochemical properties of pure and graphene-modified hybrid silica sol–gel coatings deposited on anodized AZ31B magnesium alloys. The precursor solution was prepared using tetraethoxysilane (TEOS) and 3-glycidoxypropyl-trimethoxysilane (GPTMS), with the addition of chemically modified graphene nanosheets (GN-chem). Homogeneous and adherent coatings were obtained using GPTMS-TEOS (GT) and GPTMS-TEOS-GN-chem (GT/GN-chem) solutions with uniform thickness around 4 µm. Raman, SEM images and EDS analyses confirmed the presence of graphene nanosheets in the coatings. Potentiodynamic polarization results using 0.05 M NaCl electrolyte solution showed that graphene containing silica coatings significantly improve the corrosion resistance of AZ31B alloys. In addition, a significant passive region was observed for GT/GN-chem coatings.

[ES] Entrevista realizada a la Profesora de Investigación del CSIC Alicia Durán, con motivo de la reciente publicación del libro del que es coeditora «Welcome to the Glass Age: Celebrating the United Nations International Year of Glass 2022», en la colección «Divulgación» del CSIC. Esta publicación tiene como objetivo la conmemoración del Año Internacional del Vidrio, IYOG2022, así declarado por las Naciones Unidas.

[EN] Fluoride is a natural contaminant of water – that endangers many people worldwide when present in concentrations higher than 2 ppm. Here, fluoride removal by four different nanostructured colloidal particles (SiO2@ZrO2nc, SiO2@ZrO2c, @ZrO2nc, and @ZrO2c) was measured in batch systems within a period of 24 h. Surprisingly, these materials removed fluoride from the water solutions and reached equilibrium in less than 10 min. The combination of high specific surface and fast fluoride removal placed these materials among the top materials currently known in fluoride removal. Also, the impact of element leaching was measured and quantified. The influence of time, pH, and fluoride concentration on leaching of Zr and Si was evaluated with a response surface methodology. Leaching of Zr and Si continued for several hours and depended on first-order, quadratic and cross-product coefficients. Previous studies of fluoride removal with zirconium oxide often assumed that a decrease in fluoride concentration in the solution indicated that fluoride was bound to the surface of the oxide. Zirconium oxide's solubility in water is low, but not zero. Hence, Zr might have formed soluble fluorocomplexes. This is the first report of fluoride removal with zirconium oxide that studied the leaching of the solid to exclude the formation of soluble fluorocomplexes., [ES] El fluoruro es un contaminante natural del agua, el cual pone en peligro a muchas personas en todo el mundo cuando está presente en concentraciones superiores a 2 ppm. Aquí, la eliminación de fluoruro por cuatro partículas coloidales nanoestructuradas diferentes (SiO2@ZrO2nc, SiO2@ZrO2c, @ZrO2nc y @ZrO2c) se midió en sistemas estancos en un período de 24 h. Sorprendentemente, estos materiales eliminaron el fluoruro de las soluciones acuosas y alcanzaron el equilibrio en menos de 10 minutos. La combinación de una superficie específica alta y una rápida eliminación de fluoruro colocó a estos materiales entre los mejores actualmente conocidos en la eliminación de fluoruro. Además, se midió y cuantificó el impacto de la lixiviación de elementos. La influencia del tiempo, el pH y la concentración de fluoruro en la lixiviación de Zr y Si se evaluó con una metodología de superficie de respuesta. La lixiviación de Zr y Si continuó durante varias horas y dependió de coeficientes de primer orden, cuadráticos y de productos cruzados. Los estudios previos de eliminación de fluoruro con óxido de circonio a menudo asumían que una disminución en la concentración de fluoruro en la solución indicaba que el fluoruro estaba unido a la superficie del óxido. La solubilidad del óxido de circonio en agua es baja, pero no nula. Por tanto, Zr podría haber formado complejos fluorados solubles. Este es el primer reporte de eliminación de fluoruro con óxido de circonio que estudió la lixiviación del sólido para excluir la formación de fluorocomplejos solubles.