While ball-milling is becoming one of the common tools used by synthetic chemists, an increasing number of studies highlight that it is possible to further expand the nature and number of products which can be synthesized, by heating the reaction media during mechanochemical reactions. Hence, developing set-ups enabling heating and milling to be combined is an important target, which has been looked into in both academic and industrial laboratories. Here, we report a new approach for heating up reaction media during ball-milling reactions, using induction heating (referred to as i-BM). Our set-up is attractive not only because it enables a very fast heating of the milling medium (reaching ≈80 °C in just 15 s), and that it is directly adaptable to commercially-available milling equipment, but also because it enables heating either the walls of the milling jars or the beads themselves, depending on the choice of the materials which compose them. Importantly, the possibility to heat a milling medium “from the inside” (when using for example a PMMA jar and stainless steel beads) is a unique feature compared to previously proposed systems. Through numerical simulations, we then show that it is possible to finely tune the properties of this heating system (e.g. heating rate and maximum temperature reached), by playing with the characteristics of the milling system and/or the induction heating conditions used. Lastly, examples of applications of i-BM are given, showing how it can be used to help elucidate reaction mechanisms in ball-milling, to synthesize new molecules, and to control the physical nature of milling media.

We present a new operando approach for following reactions taking place in mechanochemistry, relying on the analysis of the evolution of the sound during milling.

Mechanochemistry enables the facile ¹⁷O-enrichment of (bi)carbonate salts for high-resolution ssNMR analyses.

This study investigates hyperpolishing of Zerodur^® substrates via chemical-mechanical polishing (CMP) using silica (SiO₂) and ceria (CeO₂) nanoparticles as controlled nano-abrasives. A pre-polishing stress-mirror stage was combined with systematic use of nanoparticles of variable size to evaluate surface-state evolution via optical rugosimeter, HRSEM, cross-sectional HRTEM, and XPS. A set of hexagonal mirrors with a circumscribed diameter of 30 mm was polished for one hour with each nanoparticle type. All tested slurries significantly improved surface quality, with both the smallest (37 nm) and largest (209 nm) SiO₂ particles achieving similar final roughness, though larger particles showed a slight performance advantage that could be offset by longer polishing with smaller particles. CeO₂ nanoparticles (30 nm) produced even better process efficiency and surface finishes than 37 nm SiO₂, demonstrating higher chemical-mechanical polishing efficiency with CeO₂. Sequential polishing strategies, first with 209 nm SiO₂, then with 37 nm SiO₂ and 30 nm CeO₂, also enhanced surface quality, confirming trends from single-particle trials. One of the most effective protocols was adapted and scaled up to 135 mm Zerodur^® mirrors with spherical and plano geometries, representative of precision optical components. The strategic approach adopted to achieve a high-quality surface finish in a reduced processing time relies on the sequential use of nanoparticles acting as complementary nano-abrasives. Indeed, applying two hours of polishing with 209 nm SiO₂ followed by two hours with 37 nm SiO₂ yielded exceptional results, with area roughness (Sa) values of 1 Å for spherical and 0.9 Å for plano surfaces. These results demonstrate the capability of nanoparticle-assisted CMP to produce sub-nanometric surface finishes and offer a robust, scalable approach for high-end optical manufacturing.

The importance of (bi)carbonate salts cannot be understated. They are vital to the Earth’s geology and ecosystems and are used as precursors by chemists for the synthesis of functional materials. Naturally, solid-state NMR (ssNMR) appears as the spectroscopic tool of choice to probe the atomic-level structure and dynamics of (bi)carbonate salts. Of the possible nuclei available as spectroscopic probes in carbonate and bicarbonate ions (i.e., ¬1H, 13C, and 17O), oxygen-17 is highly attractive. Yet, it is seldom employed, largely due to its low natural abundance (0.04%) and lack of practical enrichment protocols. Recently, we reported an effective 17O labeling strategy involving mechanochemistry of Na2CO3·H2O, Na2CO3, NaHCO3, K2CO3·1.5H2O, and KHCO3, and recorded their 17O NMR spectral fingerprints near room temperature. In this work, ultra-low temperature (i.e., 100 K) 17O ssNMR spectra of these phases are acquired at two magnetic fields, 14.1 T and 18.8 T, to extract the 17O NMR parameters δiso, CQ, and ηQ for the different oxygen sites, and to further study the influence of dynamics on the spectra. We compare the experimental 17O NMR parameters to those computed with GIPAW-DFT calculations both on static models, and after averaging by molecular dynamics (MD). This approach was taken to aid in analyzing the structure-spectra relationships and shed light on the dynamics. Lastly, we report the static GIPAW-DFT calculations of 17O NMR parameters for a series of other carbonate salts of interest, further expanding upon current experimental 17O ssNMR results.

With the rapid increase in temperatures around the planet, the need to develop efficient means to reduce CO2 emissions has become one of the greatest challenges of the scientific community. Many different strategies are being studied worldwide, one of which consists of trapping the gas into porous materials, either for its short- or long-term capture and storage, or its re-use for the production of value-added compounds. Yet, to further the development of such systems, there is a real need to fully understand their structure and properties, including at the molecular-level following the physisorption and/or chemisorption of CO2 (which can lead to various species, including carbonate and bicarbonate ions). In this context, 17O NMR naturally appears as the analytical tool of choice, because of its exquisite sensitivity to probe subtle differences in oxygen bonding environments. To date, it has scarcely been used, due to the very low natural abundance of 17O (0.04%), and the difficulty in purchasing or obtaining commercial 17O-labeled compounds adapted to such investigations (e.g., 17O-CO2(g), or 17O-enriched Na- and K- (bi)carbonate salts, which can be readily transformed into CO2). Herein, we demonstrate how, using mechanochemistry, it is possible to enrich with 17O a variety of Na- and K- (bi)carbonate salts in a fast, economical, scalable, and user-friendly way. The high enrichment levels enabled recording the first high-resolution 17O ssNMR spectra of these phases at different temperatures and magnetic fields. From these, the typical spectral signatures of (bi)carbonate ions could be obtained, showing their strong sensitivity to local environments and dynamics. Lastly, we show how thanks to the selective 17O-labeling, other aspects of the reactivity of carbonates in materials can be unveiled using in-situ 17O ssNMR. In the long run, it is expected that this work will open the way to more profound investigations of the structure and properties of carbon capture and storage systems, and, more generally speaking, of functional materials containing carbonates.