Such reactions have not yet been feasible for mechanochemical investigation, even by ex situ approaches which require many individual experiments to map the evolution of a reaction profile. However, in many cases, materials are expensive or toxic. Similarly, difficulties with data collection strategies for established TRIS-XRPD methods have demanded the use of large solid loadings, typically hundreds of milligrams 13, 27. In turn, it has not been yet possible to extract the intricate mechanistic detail required to fully elucidate the mechanisms of mechanochemical transformations from TRIS data.įor instance, the determination of crystallite size which has appeared as a fundamental factor in mechanochemical transformations 32, 33, remains largely outside the scope of current TRIS capabilities. Despite the significant progress made in the study of mechanochemical reactions through TRIS-XRPD, the quality of attainable data has remained poor. TRIS-XRPD has proved especially promising for identifying unexpected and short-lived intermediates, including indications of short-lived amorphous phases 31. This has included studies on the rates and mechanisms of both chemical 29 and physical transformations 30. As mechanochemistry is predominantly a solid-state synthesis technique, TRIS-X-ray powder diffraction (XRPD) has remained a focal point for mechanochemical investigation. For example, TRIS Raman spectroscopy 26, 27 has allowed unrivalled insight into the rates and mechanisms of ball milling covalent organic chemical reactions and solid–solvent interactions 26, while advances in TRIS X-ray spectroscopy have allowed the study of redox chemistry during nanoparticle mechanosynthesis 28. Time-resolved in situ (TRIS) monitoring approaches have opened the door to exceptional detail regarding mechanochemical reactions 13. Such reactions can be only studied by directly probing the reaction in situ during mechanical treatment. Moreover, examples are known where the stop-start ex situ approach causes the system to evolve via a pathway alternative to the unperturbed reaction 24, 25. However, many systems continue to transform even after milling is stopped 22, 23. Where reaction products are long-lived, ex situ methods provide a powerful means to investigate mechanochemical mechanisms. Traditionally, mechanochemical reactions have been studied ex situ, wherein the reaction is stopped and material is removed from the reactor for analysis.
#Peak splitting xray diffraction full#
This lack in understanding and control represents a significant barrier to realising the full potential of this world-changing technology. Despite decades of research 21, the fundamental principles which drive mechanochemical reactions remain poorly understood. Providing “greener” and potentially less-expensive strategies than traditional solution methods 1, 17, 18, 19, mechanochemistry was dubbed by the International Union for Pure and Applied Chemistry (IUPAC) as one of the 10 chemical innovations that will change our world 20. It is increasingly clear that many traditional solution-based chemical reactions can be performed in the presence of very little or no solvent using mechanochemical approaches 16. Mechanochemistry has emerged as an attractive and sustainable synthetic tool 1, 2 with applications for the synthesis of organic 3, 4, 5, 6, 7, inorganic 8, 9, 10, 11 and hybrid metal-organic molecules and materials 12, 13, 14, 15.
Our strategy is applied to model systems, including inorganic, metal-organic, and organic mechanosyntheses, resolves previously misinterpreted mechanisms in mechanochemical syntheses, and promises broad, new directions for mechanochemical research. This offers a direct avenue towards the mechanochemical investigation of reactions comprising scarce, expensive, or toxic compounds. This strategy applies to all chemistries, is readily implemented, and yields high-quality diffraction data even using a low energy synchrotron source. Moreover, microstructural parameters (crystal size and microstrain) can be also determined with high confidence. Accurate phase compositions, comparable to those obtained by ex situ measurements, can be obtained with small sample loadings. Here we report how a combination of miniaturised grinding jars together with innovations in X-ray powder diffraction data collection and state-of-the-art analysis strategies transform the power of TRIS synchrotron mechanochemical experiments. Time resolved in situ (TRIS) monitoring has revolutionised the study of mechanochemical transformations but has been limited by available data quality.
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