Institut de Chimie de la Matière Condensée de Bordeaux

ABSTRACT Glasses containing simultaneously iron and manganese have been widely used in medieval times to produce a wide range of colorations from green to purple. Technical recipes are, however, not known due to the lack of historical documents. A large panel of medieval‐like glasses containing variable amounts of iron and manganese oxides has been produced under variable atmosphere (air, H 2 , O 2 ) and at different melting temperatures (1200°C, 1350°C, and 1500°C). Using optical absorption spectroscopy to probe the glass coloration, information has been derived on the interactions between Fe 2+ , Fe 3+ , Mn 2+ , and Mn 3+ ions during the glass synthesis. An abacus relating temperature and the MnO to (MnO+FeO) ratio has been set up and used to deduce the melting temperatures of a set of historical glasses from the literature. The derived temperatures were, however, too high for medieval furnaces, quantitatively confirming the common knowledge that the synthesis atmosphere in the medieval furnaces had to be more reduced than pure air. The relationship between glass coloration and synthesis parameters, the extensive set of glasses studied in this work, quantitatively allowed to enlighten the effect of the so‐called “glassmaker's soap” for the first time and the conditions to obtain an uncolored glass at any temperature.

A selective oxidation of oximes under metal-free, photocatalyzed conditions, visible light and air, affords various heterocycles in the presence of ketones, nitriles and alkynes. Mechanistic studies suggest an H-bond driven photocatalyzed process.

This work explores water hydrolysis using magnesium as a decentralized dihydrogen source for off-grid households. A dedicated reactor design enabled on-demand dihydrogen generation, coupled with a Proton Exchange Membrane Fuel Cell (PEMFC) for electricity and heat production. Different energy management strategies were compared, highlighting the limitations of single-purpose approaches and the benefits of converting surplus electricity to heat. The integration of photovoltaic generation further reduced magnesium demand by 30%, thus reducing storage requirements to close to 1565 kg of magnesium powder per year, i.e., a volume of 0.9 m3 to cover the heat and electricity needs of a four-person household. Results demonstrate that combining water hydrolysis with magnesium and renewables provides a feasible and sustainable solution for autonomous energy supply in isolated sites.

22955

The development of miniaturized, remotely addressable sensing devices is crucial in a variety of fields, including healthcare, environmental monitoring, and security. This study introduces an optrode sensor comprising a multimaterial fiber composed of a phosphate glass cladding and a continuous Zn wire core, interfaced with a photoactive ZnO coating on its tip, deposited by anodization. It is shown that this optrode can promote photoelectrochemical reactions under illumination with UV light when immersed in an aqueous electrolyte. Proof‐of‐principle experiments demonstrate that these optrodes produce a glucose‐responsive photocurrent, opening the way to biomedical applications. This optical sensor shows promise, as it would ultimately allow the decoupling of input stimuli, i.e., potential and light excitation, over a long distance. Due to its advantages in terms of integration, detection speed, and ease of use, these ZnO/Zn/phosphate optrodes hold significant potential for remote analysis and implantable sensors.

• Crystallization of the SrF 2 phase in the novel xGeO 2 – (100-x) (BaF 2 , SrF 2 , ½ In 2 O 3 ) glass system is demonstrated. • Doping of the glass ceramics with Eu 2 O 3 leads to an increase in transparency attributed to a decrease in SrF 2 crystal sizes. • Part of the Eu 3+ ions enter the SrF 2 crystallites. The development of transparent glass-ceramics is a challenging endeavor in the field of mid-infrared photonics in order to fabricate robust and optically efficient materials. In this study, the glass-forming region of the novel xGeO 2 – (100-x) (BaF 2 , SrF 2 , ½ In 2 O 3 ) system is investigated, while SrF 2 -forming glass-ceramic compositions are identified. DSC measurements upon Eu 2 O 3 doping show a decrease in the onset temperature of SrF 2 crystallization. In the meantime, both XRD and TEM acquisitions confirm a decrease in crystal size as the dopant content increases. Part of the Eu 3+ ions enter the SrF 2 crystallites, as demonstrated by steady-state and time-resolved spectroscopies. Hence, we demonstrate that europium oxide doping enables a precise control of SrF 2 nanocrystal size in the GeO 2 -BaF 2 -SrF 2 -In 2 O 3 system. Our findings open doors towards the nanostructure tailoring of SrF 2 -containing germanate glass-ceramics using rare-earth dopants for luminescence and laser applications.

International audience

The Purcell effect can be used in plasmonic multipod structures to enhance the spontaneous emission of magnetic dipole transitions, which are notoriously weak in nature, while inhibiting the emission of the electric dipole transition. Here, the optical emission from a magnetic dipole transition in a dielectric particle surrounded by metallic satellites, positioned so as to be formal solutions to the Thomson problem, are optimized. Quasi-normal modes (QNMs) are employed for the analysis, offering a significant advantage over traditional real-frequency approaches in reducing a vast parameter space and providing more physical insight. We demonstrate that highly symmetrical N-pods, which can currently be fabricated, are excellent candidates for achieving a large, orientation- and volume-independent magnetic Purcell factor with minimal Ohmic losses. Additionally, we successfully suppress the electric dipole transition, obtaining a magnetic branching ratio exceeding 95% for nearly all N-pod particles. For particles exhibiting a high degree of symmetry, radiated magnetic Purcell factors in excess of 180 are predicted after optimization of the core and satellite radii.

Abstract Ideally, new materials should foster sustainability. How to apply this to high entropy alloys (HEAs) is the subject of the present overview. We show HEAs have a number of potential applications in sustainable technologies. They may also slot sustainably into a circular economy, if they can mediate a lowering of the life cycle energy rate. This term forecasts the rate of energy expenditure over the life cycle of a replaceable component. The energy cost of high entropy alloy production, and the challenges they will present to recycling, may be justified from a sustainability perspective, so long as they can mediate sufficient sustainability benefits in their use phase. Promising applications include functional roles in energy production and storage and applications in gas turbines. Although high entropy alloys are most likely to be downcycled at the end of their lives, there is a growing body of literature pointing to interesting ways high entropy alloys might be produced from recycled metal flows, thereby opening up avenues to significantly lower their energy cost of production. Evidence is also presented for a possible 5th core effect in High Entropy Alloys, whereby the presence of multiple alloying additions serves to stabilize the properties against variation in composition. This effect may facilitate their production using scrap metal. The greater the co-ordination between alloy design, component design, and manufacturing innovation, the more likely HEAs will prove to be a sustainable step forward.