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The paper reports on phase composition, microhardness and wear resistance of compacts and coatings based on η-carbides (Fe,W)6C and (Fe,W)12C produced by mechanical alloying of tungsten and iron powders in petroleum ether. The compacts have been prepared by magnetic-pulse compacting, and the coatings being formed on iron substrate by the selective laser sintering. The compacts exhibit microhardness up to 9.6 GPa and high abrasive wear resistance. Friction coefficients are 0.27-0.6 and 0.33-0.53 in frictional pairs with a steel disc and a ball made of WC-Co alloy, respectively, and wear not exceeding 10 µm in the tribo-pairs. The coatings have a microhardness of 16 GPa and friction coefficients of 0.28 and 0.2 for friction with balls made of steel and WC-Co, respectively, with no wear being practically observed in tribo-pairs. Combining the mechanosynthesis and selective laser sintering is shown to be very efficient to fabricate coatings based on η-carbides (Fe,W)6C and (Fe,W)12C possessing high values of hardness and wear resistance.

Aurivillius compounds with the general formula (Bi2O2)(An-1BnO3n+1) are a highly topical family of functional layered oxides currently under investigation for room-temperature multiferroism. A chemical design strategy is the incorporation of magnetically active BiMO3 units (M: Fe3+, Mn3+, Co3+ …) into the pseudo-perovskite layer of known ferroelectrics like Bi4Ti3O12, introducing additional oxygen octahedra. Alternatively, one can try to directly substitute magnetic species for Ti4+ in the perovskite slab. Previous reports explored the introduction of the M3+ species, which required the simultaneous incorporation of a 5+ cation, as for the Bi4Ti3-2xNbxFexO12 system. A larger magnetic fraction might be attained if Ti4+ is substituted with Mn4+, though it has been argued that the small ionic radius prevents its incorporation into the pseudo-perovskite layer. We report here the mechanosynthesis of Aurivillius Bi4Ti2-xMnxNb0.5Fe0.5O12 (n = 3) compounds with increasing Mn4+ content up to x = 0.5, which corresponds to a magnetic fraction of 1/3 at the B-site surpassing the threshold for percolation, and equal amounts of Mn4+ and Fe3+. The appearance of ferromagnetic superexchange interactions and magnetic ordering was anticipated and is shown for phases with x ≥ 0.3. Ceramic processing was accomplished by spark plasma sintering, which enabled electrical measurements that demonstrated ferroelectricity for all Mn4+-containing Aurivillius compounds. This is a new family of layered oxides and a promising alternative single-phase approach for multiferroism.

Ti-based composite materials with remarkable mechanical properties and good thermal stability were obtained and studied with the purpose of employment for producing resistant and versatile components in the automotive industry. The raw materials having the overall Ti80Mn8Al6Sn3Zr2C1 composition were prepared by mechanosynthesis from powders of comprising elements; after thermal processing and by following four different sintering pathways, both in the argon flow, the four samples (S1–S4) reached a specific composition of metallic and ceramic phases. Thermal analysis and calorimetry showed that the composite materials adsorb considerable amounts of argon, these being related to the obtained composition and microstructure. The results of the thermal study were used when choosing the thermal treatment conditions for sintering; in order to select the optimal processing conditions within the four different regimes of sintering for the raw materials and the final sample with the best functional properties, a comprehensive study for determining the composition, structure and morphological features was carried out by means of X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscopy. Two samples (S1 & S4) of the obtained composite materials have increased porosity due to the presence of titanium aluminium carbides (Ti3AlC & Ti3AlC2) that are known as highly porous ceramics, therefore absorbing more argon during the preparation process. The roughness and wear tests showed that the best results (smallest roughness: Ra = 1.11 μm and smallest wear: w = 2.472·10−4 mm3 N−1 m−1) belong to the S2 sample sintered in argon for 15 min at 1100 °C and further calcinated at 1050 °C for 75 min.

The application of polymers to replace oleylamine (OLA) and oleic acid (OA) as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based processing. Herein, we report a mechanosynthesis of lead bromide perovskite nanoparticles (NPs) stabilized by partially hydrolyzed poly(methyl methacrylate) (h-PMMA) and high-molecular-weight highly-branched poly(ethylenimine) (PEI-25K). The as-synthesized NP solutions exhibited green emission centered at 516 nm, possessing a narrow full-width at half-maximum of 17 nm and as high photoluminescence quantum yield (PL QY) as 85%, while showing excellent durability and resistance to polar solvents, e.g., methanol. The colloids of polymer-stabilized NPs were directly processable to form stable and strongly-emitting thin films and solids, making them attractive as gain media. Furthermore, the roles of h-PMMA and PEI-25K in the grinding process were studied in depth. The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs. The PEI-25K with large amounts of amino groups induced significant enrichment of PbBr2 in the reaction mixture, which in turn caused the formation of CsPb2Br5-mPbBr2 and CsPbBr3-Cs4PbBr6-nCsBr NPs. The presence of CsPbBr3-Cs4PbBr6-nCsBr NPs was responsible for the high PL QY, as the Cs4PbBr6 phase with a wide energy bandgap can passivate the surface defects of the CsPbBr3 phase. This work describes a direct and facile mechanosynthesis of polymer-coordinated perovskite NPs and promotes in-depth understanding of the formation and phase conversion for perovskite NPs in the grinding process.

Pb0.67Cd0.33F2 solid solution with a fluorite-type structure has been synthesized for the first time using high-energy grinding of the initial components, PbF2 and CdF2, taken in a ratio of 2 : 1, in an inert Ar atmosphere. The dynamics of this process is investigated by X-ray diffraction analysis. The lattice parameter of the mechanosynthesis product is а = 5.768(7) A, and the average particle size is ∼50 nm.

Chemistry - a European journal 28(13), e202104409 (2022). doi:10.1002/chem.202104409, Published by Wiley-VCH, Weinheim

International audience; The mechanically assisted synthesis of organic compounds has recently focused considerable attention as it may be unique in features to selectively direct the reaction pathway. In the continuation of our work on the synthesis of modified cyclodextrins (CDs) via mechanochemical activation, we sought to discriminate the contribution of supramolecular effects and grinding during the course of a reaction in the solid state. As such, we recently investigated the influence of the particle size of β-CD in the synthesis of β-CD mesitylene sulfonate (β-CDMts) in the solid state using a vibrating ball-mill. We were particularly interested in the role of the particle size on the kinetics of the reaction. In this study, we show that grinding β-CD reduces the particles size over time down to a limit of 167 nm. The granulometric composition remains rather invariant for grinding times over 1 h. Each type of β-CD particles reacted with mesitylenesulfonyl chloride (MtsCl) to produce β-CDMts. Contrary to what could be intuitively anticipated, smaller particles did not lead to the highest conversions. The impact of grinding on the conversion was limited. Interestingly, the proportion of β-CDMts mono-substituted on the primary face significantly increased over time when the reaction was carried out in the presence of KOH as a base. The data series were confronted with kinetics models to get insight in the way the reactions proceeded. The diversity of possible models suggests that multiple mechanochemical processes can account for the formation of β-CDMts in the solid state. Throughout the study, we found that the reactivity depended more upon diffusion phenomena in the crystalline parts of the material than on the increase in the surface area of the CD particles resulting from grinding.

The formation of the cubic δ-Ta1−xN phase by high-energy ball-milling from tantalum and boron nitride (h-BN) is explored. Two different molar ratios Ta:BN, 1:1 and 2:1, were used. X-ray diffraction, scanning electron microscopy, surface area analysis by the Brunauer-Emmett-Teller method, and thermogravimetric analysis were used to characterize the products obtained. In both molar ratios and after a few minutes of milling, the mechanosynthesis of δ-Ta1−xN was observed. Increasing the entropy of the system by introducing vacancies and point defects by the high-energy ball-milling process seems to stabilize the cubic δ-Ta1−xN phase, as previous theoretical studies had reported. The phase obtained depends on the molar ratio used: in the molar ratio 1:1 a non-stoichiometric δ-Ta1−xN phase is obtained, while in the molar ratio 2:1 a stoichiometric δ-TaN phase and secondary phases are obtained. The amorphous boron remains dispersed in the material until the mechanical energy is high enough to trigger the formation of tantalum borides.

Mechanochemical synthesis of CsPbI3 , as a model system for ABX3 halides, was studied. Water was shown to strongly promote the kinetics of formation of CsPbI3 from the CsI+PbI2 mixture through increased mobility of the constituting ionic species. Since many binary and ternary halides are hygroscopic, it was concluded that the presence of small, uncontrollable and unintentional additions of water should often occur in both precursor mixtures and synthesized complex halides boosting the kinetics of formation of many, if not all, ternary organic-inorganic hybrid halides such as, for example, MAPbX3 (X=Cl, Br, I). In addition, trace amounts of water should influence the transport characteristics of complex halides. Thus, the presence of water explains, at least partially, the huge scatter in both the reported mechanochemical reaction times necessary for obtaining single-phase APbX3 perovskite halides and the activation energies of ionic diffusion in APbX3 .

The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC5, TiZrHfVTaC5, TiZrHfNbTaC5, TiZrVNbTaC5, TiHfVNbTaC5 and ZrHfVNbTaC5, were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC5, TiZrVNbTaC5 and ZrHfVNbTaC5, were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800–2200 °C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites.

Inspired by mechanic force induced S–S bridge activation in a protein context, we have developed the first mechanochemical electrophilic C–H sulfenylation of indoles in combination with iodine cata...

Designable porous materials have potential in a plethora of applications, but synthesis costs and strict reaction conditions limit their true commercialization. Herein, we show that hypercrosslinke...

A novel highly efficient photocatalyst composite BiFeO3/Fe3O4 has been synthesized by mechanosynthesis and applied to the degradation of Methylene Blue under visible light. Structural, optical and photocatalytic properties of the proposed photocatalyst composites are carefully investigated. The nanointerfaces, associated to ferrous Fe2+ ions of the Fe3O4 nanoparticles, improve the photocatalytic efficiency when compared with pure BiFeO3 or Fe3O4. The time required to the complete degradation of Methylene Blue solution is 40 min for the sample with 20% of Fe3O4 which is more than 7 times faster than the time required using BiFeO3 alone. Moreover, with the addition of H2O2 a complete degradation is achieved just after 10 min, which is faster than any other photocatalytic reaction reported for BiFeO3-based materials. This enhancement is assumed to be related to an electron drain process due to the difference between energy levels of the conduction bands of BiFeO3 and Fe3O4 combined with the direct Fenton-like process associated with the Fe2+ ions of the composites.

This review is a compilation of the green synthetic methods used in the synthesis of coumarin derivatives. Coumarins are a class of compounds with a pronounced wide range of biological activities, which have found their application in medicine, pharmacology, cosmetics and food industry. Their biological activity and potential application are highly dependent on their structure. Therefore, many researchers have been performing the synthesis of coumarin derivatives on a daily basis. High demands for their synthesis often result in an increased generation of different waste chemicals. In order to minimize the utilization and generation of toxic organic substances, green synthetic methods are applied in this manner. These methods are getting more attention in the last few decades. Green chemistry methods cover a wide range of methods, including the application of ultrasound and microwaves, ionic liquids and deep eutectic solvents, solvent-free synthesis, mechanosynthesis and multicomponent reactions. All typical condensation reactions for coumarin synthesis like Knoevenagel, Perkin, Kostanecki-Robinson, Pechmann and Reformansky reactions, have been successfully performed using these green synthetic methods. According to the authors mentioned in this review, not only these methods reduce the utilization and generation of toxic chemicals, but they can also enhance the reaction performance in terms of product yields, purity, energy consumption and post-synthetic procedures when compared to the conventional methods. Due to the significance of coumarins as biologically active systems and the recent demands of reducing toxic solvents, catalysts and energy consumption, this review provides a first full literature overview on the application of green synthetic methods in the coumarin synthesis. It covers a literature search over the period from 1995-2019. The importance of this work is its comprehensive literature survey on a specific class of heterocyclic compounds, and those researchers working on the coumarin synthesis can find very useful information on the green synthetic approaches to their synthesis. There are some reviews on the coumarin synthesis, but most of them cover only specific reactions on coumarin synthesis and none of them the whole range of green chemistry methods.

A method of low-temperature (up to 100°C) dry mechanosynthesis of calcium stearate has been developed by exposing the reaction of stearic acid and calcium hydroxide normal and tangential shear stresses in the apparatus of the satellite design of the working cavity. The efficiency of the mechanosynthesis of calcium stearate is calculated relative to a similar chemical reaction in a liquid medium. It was found that the rate of solid-phase synthesis of calcium stearate is an order of magnitude greater than the reaction rate in the liquid phase.

Chemical science 11(9), 2350 - 2355 (2020). doi:10.1039/C9SC06224F, Using the mechanosynthesis of the calcium urea phosphate fertilizer cocrystal as a model, we provide a quantitative investigation of chemical autocatalysis in a mechanochemical reaction. The application of in situ Raman spectroscopy and synchrotron X-ray powder diffraction to monitor the reaction of urea phosphate and either calcium hydroxide or carbonate enabled the first quantitative and in situ study of a mechanochemical system in which one of the products of a chemical reaction (water) mediates the rate of transformation and underpins positive feedback kinetics. The herein observed autocatalysis by water generated in the reaction enables reaction acceleration at amounts that are up to 3 orders of magnitude smaller than in a typical liquid-assisted mechanochemical reaction., Published by RSC, Cambridge

Control over the bottom up synthesis of metal nanoparticles (NP) depends on many experimental factors, including the choice of stabilising and reducing agents. By selectively manipulating these species, it is possible to control NP characteristics through solution-phase synthesis strategies. It is not known, however, whether NPs produced from mechanochemical syntheses are governed by the same rules. Using the Au NPs mechanosynthesis as a model system, we investigate how a series of common reducing agents affect both the reduction kinetics and size of Au NPs. It is shown that the relative effects of reducing agents on mechanochemical NP synthesis differ significantly from their role in analogous solution-phase reactions. Hence, strategies developed for control over NP growth in solution are not directly transferrable to environmentally benign mechanochemical approaches. This work demonstrates a clear need for dedicated, systematic studies on NP mechanosynthesis.

Current time-resolvedin situapproaches limit the scope of mechanochemical investigations possible. Here we develop a new, general approach to simultaneously follow the evolution of bulk atomic and electronic structure during a mechanochemical synthesis. This is achieved by coupling two complementary synchrotron-based X-ray methods: X-ray absorption spectroscopy (XAS) and X-ray diffraction. We apply this method to investigate the bottom-up mechanosynthesis of technologically important Au micro and nanoparticles in the presence of three different reducing agents, hydroquinone, sodium citrate, and NaBH4. Moreover, we show how XAS offers new insight into the early stage generation of growth species (e.g.monomers and clusters), which lead to the subsequent formation of nanoparticles. These processes are beyond the detection capabilities of diffraction methods. This combined X-ray approach paves the way to new directions in mechanochemical research of advanced electronic materials.

U okviru doktorskog rada sintezirani su 2,3-disupstituirani (1 – 130) i 3-supstituirani derivati kinazolin-4(3H)-ona (131 – 136) u niskotemperaturnim eutektičkim otapalima s ciljem njihove primjene u sintezi heterocikala. Sinteze derivata kinazolin-4(3H)-ona provedene su konvencionalno, potpomognute mikrovalovima i ultrazvukom te mehanokemijskim reakcijama. Niskotemperaturna eutektička otapala za sintezu novih spojeva priređena su miješanjem kolin-klorida (ChCl) i različitih amida, karboksilnih kiselina, ugljikohidrata i alkohola u određenom molarnom omjeru. Optimiranje reakcijskih uvjeta za svaku klasu spojeva provedeno je na odabranoj modelnoj reakciji izborom najpovoljnijeg niskotemperaturnog eutektičkog otapala, volumena otapala, temperature i vremena trajanja reakcije. Pri optimiranju mehanokemijske sinteze ispitan je dodatno i utjecaj količine kuglica. Derivati 2-merkapto-3-supstituiranih kinazolin-4(3H)-ona (1 – 50) sintetizirani su u otapalu ChCl : urea reakcijom antranilne kiseline i alifatskih te aromatskih izotiocijanata konvencionalno s iskorištenjima 19 – 76 %, sintezom potpomognutom mikrovalovima u iskorištenjima 10 – 49 %, sintezom potpomognutom ultrazvukom u iskorištenjima 17 – 64 % i mehanokemijskom sintezom s iskorištenjima 48 – 88 %. 2-metil-3-supstituirani kinazolin-4(3H)-oni (51 – 87) sintetizirani su reakcijom 2-metilbenzoksazin-4-ona i aromatskih amina te hidrazida kumarina i piridin-2,6-dikarbohidrazida u otapalu ChCl : urea konvencionalno s iskorištenjima 17 – 77 %, sintezom potpomognutom mikrovalovima (10 – 41 %), sintezom potpomognutom ultrazvukom (15 – 56 %) i mehanokemijskom sintezom (45 – 87 %). Schiffove baze kinazolin-4(3H)-ona (88 – 130) sintetizirane su u otapalu ChCl : malonska kiselina reakcijom 3-amino-2-metilkinazolin-4(3H)-ona i aromatskih aldehida konvencionalno u iskorištenjima 63 – 97 %, sintezom potpomognutom mikrovalovima (39 – 68 %), sintezom potpomognutom ultrazvukom (40 – 80 %) te mehanokemijskom sintezom u visokim iskorištenjima 79 – 97 %. Trokomponentnim reakcijama antranilnih kiselina, trimetilortoformijata i aromatskih amina u otapalu ChCl : urea detektirani su 3-supstituirani derivati kinazolin-4(3H)-ona (130 – 136) u tragovima. Najbolja iskorištenja reakcija u sintezi 2,3-disupstituiranih derivata kinazolin-4(3H)-ona (1 – 130) dobivena su mehanokemijskom sintezom koju karakteriziraju najkraće vrijeme reakcije i čistoća izoliranih produkata. Zatim slijedi konvencionalna sinteza, sinteza potpomognuta ultrazvukom i s najmanjim iskorištenjem sinteza potpomognuta mikrovalovima. Korištenjem niskotemperaturnih eutektičkih otapala u sintezi smanjen je štetan utjecaj na okoliš organskih otapala i katalizatora, skraćeno je vrijeme trajanja reakcija, jednostavna je izolacija i pročišćavanje produkata te omogućeno recikliranje otapala. Strukture svih sintetiziranih spojeva potvrđene su 1H- i 13C-NMR spektroskopijom te masenom spektrometrijom. In the doctoral thesis 2,3-disubstituted (1 – 130) and 3-substituted quinazolin-4(3H)-one derivatives (130 – 136) are synthesized in deep eutectic solvents to investigate their application in the synthesis of heterocycles. Syntheses of quinazolin-4(3H)-one derivatives were performed conventionally, by microwave-assisted and ultrasound-assisted synthesis and mechanochemical reactions as well. Deep eutectic solvents for the synthesis of new compounds were prepared by mixing of choline chloride (ChCl) with various amides, carboxylic acids, carbohydrates and alcohols in a specific molar ratio. The optimization of the reaction conditions for each class of compounds was carried out on the selected model reaction by choosing the most favourable deep eutectic solvents, volume, temperature and reaction time. The influence of the amount of balls in mechanochemical synthesis was also optimized. 2-mercapto-3-substituted quinazolin-4(3H)-one derivatives (1 – 50) were synthesized in ChCl: urea deep eutectic solvent by reaction of anthranilic acids and aliphatic and aromatic isothiocyanates conventionally with yields 19 – 76%, by microwave-assisted synthesis (10 – 49%), by ultrasound-assisted synthesis (17 – 64%) and by mechanochemical synthesis (48 – 88%). 2-methyl-3-substituted quinazolin-4(3H)-one derivatives (51 – 87) were synthesized by the reaction of 2-methylbenzoxazin-4-one and aromatic amines and coumarinyl hydrazides and pyridine-2,6-dicarbohydrazide in ChCl: urea conventionally with yields 17 – 77%, by microwave-assisted synthesis (10 – 47%), by ultrasound-assisted synthesis (15 – 56%) and by mechanochemical synthesis (45 – 87%). Quinazolin-4(3H)-one Schiff bases (88 – 130) were synthesized in ChCl: malonic acid from 3-amino-2-methylquinazolin-4(3H)-ones and aromatic aldehydes conventionally with yields 63 – 97%, by microwave-assisted synthesis (39 – 68%), by ultrasound-assisted synthesis (40 – 80%) and by mechanochemical synthesis with high yields 79 – 97%. 3-substituted quinazolin-4(3H)-one derivatives (130 – 136) were detected in traces obtained by a three-component reaction of anthranilic acids, trimethyl orthoformate and aromatic amines. The best yields of the reactions in the synthesis of 2,3-disubstituted quinazolin-4(3H)-one derivatives (1 – 130) were obtained by mechanochemical synthesis, which is characterized by the shortest reaction time and the purity of the isolated products. Lower yields were obtained with conventional synthesis, ultrasound-assisted synthesis, and the lowest yields were achieved by microwave-assisted synthesis. With the use of deep eutectic solvents in the synthesis, the harmful impact of organic solvents and catalysts on the environment is reduced, the reaction time is shorter, the isolation and purification of products are simple, and the recycling of solvents is enabled. The structures of all synthesized compounds were confirmed by 1H- and 13C-NMR spectroscopy and mass spectrometry.

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2022, Tutora: Eva Carolina Sañudo Zotes, Lanthanide 2D Metal-Organic-Frameworks (MOFs) are very interesting materials due to their magnetic and luminous characteristics. Previous studies have shown that this MOFs with structure [Ln(CH3COO)(PhCOO)2] can be synthesized by a microwave reaction, generating relatively large crystals and a high yield. Unfortunately, they carry two drawbacks: a high usage of solvent, and a very limited outcome, since this type of microwave reaction limits the quantity of production, up to the scale of mg. In this project, other ways to synthesize MOFs in larger scales will be deeply studied, through the use of the mechanosynthesis process. Firstly, a manual mechanosynthesis will be tested. Consequently, if the results end up being favorable, we will proceed to test an automatic mechanosynthesis. Hence, the synthesis will consider reproducible parameters and a direct approach to a possible production on a large or, even, industrial scale

Green mechanosynthesis, free solvent, has been used for preparing a series of supramolecular complexes. Through directional hydrogen bonds and π-cation interaction can be prepared complexes with different states of aggregation of matter, where stoichiometry plays an essential role. When the stoichiometric ratio between the two compounds was 1:1, a solid product is obtained. But, when the ratio is higher, products are obtained as gel or paste to reach low viscosity liquids. Also, the structure of such complexes that form three-dimensional aggregates between C12TAC and phenol derivatives can explain the different aggregation states for final products and this may be the key to understand the viscosity reduction mechanism. Keywords: Supramolecular complex, Mechanosynthesis, Hydrogen bond, Π-cation interactions, Change of physical state

Hydroxyfluorapatite Ca10(PO4)6(OH)F (HFA) powders were prepared by mechanosynthesis method using planetary ball milling with various parameters. X-ray Diffraction (XRD), Infrared (IR) and Raman spectroscopies, Energy Dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) methods were employed to characterize the synthesized nanoparticles. Four factors (rotation speeds of disk, mass of balls, initial mass of powder and milling time) were investigated to understand their effect on the milling process and the formation of HFA nanocrystallite. Taguchi's design, with just 16 experiments (an L16 orthogonal array), was used to evaluate the impact of these parameters on six distinct properties, namely the crystallite size (nm), the percentage of crystallinity, the specific surface area (m2/g), the Ca/P atomic ratio, the percentages of the apatite and calcite phases. The average effects of the milling parameters and the signal-to-noise ratio (SN) were discussed. ANOVA analysis was used to determine the importance, the proportion of factor participation and also the influence of process parameters on responses. The Taguchi results indicated that the mass of balls and the rotation speed were found to be the most influential factors on the purity of compounds. The ball to powder weight ratio (BPR) was also introduced to study its effect on the synthesis process. Transmission Electron Microscopy (TEM), Scanning Electronic Microscopy (SEM) and Dynamic Light Scattering (DLS) revealed that milled HFA powders contained a nano-sized agglomerate.

International audience; This study concerns the development of an innovative manufacturing process for oxide-dispersion strengthened steels (hereafter referred to as "ODS") by mechanosynthesis. As part of materials development for Sodium-cooled Fast Reactors (SFR), the aim is to prevent the growth of undesirable micrometric precipitates which can drastically degrade steel's mechanical properties. This new process introduces Y2Ti2O7 pyrochlore oxide nanoparticles directly into Fe-Cr metallic powder through mechanical milling, as compared to the standard Y2O3 + TiO2. This study enables the validation of the method of introducing precipitates in the form of Y2Ti2O7 oxides as an efficient way to obtain competitive ODS steels, with a more homogeneous microstructure, less coarse precipitates and more reliable impact properties compared to the conventional process. Moreover, it reveals the importance of the features of the manufacturing process, particularly of milling intensity and reinforcement rate, on the microstructure and mechanical properties of ODS steel. The results reveal promising perspectives concerning the features of ODS steel manufacturing.

A family of Ruddlesden–Popper (n = 1) layered perovskite-related phases, Az2PbClxBr4−x with composition 0 ≤ x ≤ 4 were obtained using mechanosynthesis. These compounds are isostructural with K2NiF4 and therefore adopt the idealised n = 1 Ruddlesden–Popper structure. A linear variation in unit cell volume as a function of anion average radius is observed. A tunable bandgap is achieved, ranging from 2.81 to 3.43 eV, and the bandgap varies in a second-order polynomial relationship with the halide composition.

Three chitosan-derived compounds, Ch-I, Ch-Qn, and Ch-TPA, were synthesized through condensation reactions between high-molecular weight chitosan and three different aldehydes. Mechanosynthesis, a fast and solvent-free synthesis method, was used instead of a depolymerization. The chemical structure of the compounds was elucidated by Fourier-Transform Infrared (FT-IR) spectroscopy. The optical properties of the new compounds were evaluated by ultraviolet/visible (UV/Vis) and fluorescence spectroscopic techniques. The compounds Ch-I, Ch-Qn, and Ch-TPA presented absorptions in the range of 273 to 400 nm and emissions between 300 and 700 nm with Ch-TPA presenting the greatest redshift in absorption and emission. Ch-I, Ch-Qn, and Ch-TPA were characterized by the Z-scan technique, and the results indicate that Ch-I, Ch-Qn, and Ch-TPA exhibit non-linear optic behavior. Ch-TPA showed the most promising optical properties. These results indicate that it is possible to obtain promising materials derived from chitosan using mechanosynthesis and using high-molecular weight chitosan without the need to depolymerize it. Mechanosynthesis requires a short reaction time, is free of solvents, and has the potential for biomedical applications as optical and/or fluorescent biosensors.