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Adam A. L. Michalchuk

Bio: Adam A. L. Michalchuk is an academic researcher from Bundesanstalt für Materialforschung und -prüfung. The author has contributed to research in topics: Mechanochemistry & Materials science. The author has an hindex of 15, co-authored 49 publications receiving 536 citations. Previous affiliations of Adam A. L. Michalchuk include University of Edinburgh & University of Strathclyde.

Papers published on a yearly basis

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Journal ArticleDOI
TL;DR: In this paper, the authors address the question of what is meant by these terms, why have they evolved, and does it really matter how a process is called, which parameters should be defined to describe unambiguously the experimental conditions such that others can reproduce the results, or to allow a meaningful comparison between processes explored under different conditions?
Abstract: Over the decades, the application of mechanical force to influence chemical reactions has been called by various names: mechanochemistry, tribochemistry, mechanical alloying, to name but a few. The evolution of these terms has largely mirrored the understanding of the field. But what is meant by these terms, why have they evolved, and does it really matter how a process is called? Which parameters should be defined to describe unambiguously the experimental conditions such that others can reproduce the results, or to allow a meaningful comparison between processes explored under different conditions? Can the information on the process be encoded in a clear, concise, and self-explanatory way? We address these questions in this Opinion contribution, which we hope will spark timely and constructive discussion across the international mechanochemistry community.

71 citations

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TL;DR: The first in situ study of RAM-induced co-crystallisation monitored using synchrotron X-ray powder diffraction is presented, providing new insight into the role of various experimental parameters in conventional mechanochemistry using liquid-assisted grinding techniques.

68 citations

Journal ArticleDOI
TL;DR: The α-glycine + β-malonic acid system was previously shown to adhere to divergent reaction pathways under mechanical treatment, but this system's complexity was further amplified when mechanical treatment was observed to yield yet another divergent Reaction path, producing either a known salt, glycinium semi-malonate, or what is at present an unidentified phase.
Abstract: There is, at present, a substantial lack of mechanistic-level understanding of mechanochemical processes, despite their current widespread use. The system α-glycine + β-malonic acid was previously shown to adhere to divergent reaction pathways under mechanical treatment. In the present study, this system's complexity was further amplified when mechanical treatment was observed to yield yet another divergent reaction path, producing either a known salt, glycinium semi-malonate (GSM), or what is at present an unidentified phase. Isolating the two major mechanical “actions” – impact and shear – it was observed that each of these treatments favours a different product; shear yielding GSM and impact inducing production of the novel phase. Combination of isolated treatments with milling studies demonstrated two distinct regions within the milling jar, the jar ends and the jar shaft. While sample located in the latter undergoes larger amounts of shear treatment, sample located in the former is privy to both shearing and impact, depending on both its ability to tablet and the geometry with which this tablet forms. Following tablet formation, in which the major stress appears to be shear, sample located in the milling jar ends is subsequently treated by pure impact. This study offers unique insights towards a mechanistic understanding of mechanochemistry and its processes.

59 citations

Journal ArticleDOI
TL;DR: Kinetic analysis of RI‐XRPD allows, for the first time, observation of a mechanistic shift over the course of mechanical treatment, resulting from time evolving conditions within the mechanoreactor.
Abstract: Mechanochemical methods offer unprecedented academic and industrial opportunities for solvent-free synthesis of novel materials. The need to study mechanochemical mechanisms is growing, and has led to the development of real-time in situ X-ray powder diffraction techniques (RI-XRPD). However, despite the power of RI-XRPD methods, there remain immense challenges. In the present contribution, many of these challenges are highlighted, and their effect on the interpretation of RI-XRPD data considered. A novel data processing technique is introduced for RI-XRPD, through which the solvent-free mechanochemical synthesis of an organic salt is followed as a case study. These are compared to ex situ studies, where notable differences are observed. The process is monitored over a range of milling frequencies, and a nonlinear correlation between milling parameters and reaction rate is observed. Kinetic analysis of RI-XRPD allows, for the first time, observation of a mechanistic shift over the course of mechanical treatment, resulting from time evolving conditions within the mechanoreactor.

46 citations

Journal ArticleDOI
TL;DR: In this paper, a fully-ab initio approach based on concepts of vibrational energy transfer was proposed to predict impact sensitivities for a series of chemically, structurally and energetically diverse molecular materials.
Abstract: The ease with which an energetic material (explosives, propellants, and pyrotechnics) can be initiated is a critical parameter to assess their safety and application. Impact sensitivity parameters are traditionally derived experimentally, at great cost and risk to safety. In this work we explore a fully ab initio approach based on concepts of vibrational energy transfer to predict impact sensitivities for a series of chemically, structurally and energetically diverse molecular materials. The quality of DFT calculations is assessed for a subset of the materials by comparison with experimental inelastic neutron scattering spectra (INS). A variety of models are considered, including both qualitative and quantitative analysis of the vibrational spectra. Excellent agreement against experimental impact sensitivity is achieved by consideration of a multi-phonon ladder-type up-pumping mechanism that includes both overtone and combination pathways, and is improved further by the added consideration of temperature. This fully ab initio approach not only permits ranking of energetic materials in terms of their impact sensitivity but also provides a tool to guide the targeted design of advanced energetic compounds with tailored properties.

45 citations


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Journal ArticleDOI
TL;DR: A brief overview of the recent achievements and opportunities created by mechanochemistry, including access to materials, molecular targets, and synthetic strategies that are hard or even impossible to access by conventional means are provided.
Abstract: The past decade has seen a reawakening of solid-state approaches to chemical synthesis, driven by the search for new, cleaner synthetic methodologies. Mechanochemistry, i.e., chemical transformations initiated or sustained by mechanical force, has been advancing particularly rapidly, from a laboratory curiosity to a widely applicable technique that not only enables a cleaner route to chemical transformations but offers completely new opportunities in making and screening for molecules and materials. This Outlook provides a brief overview of the recent achievements and opportunities created by mechanochemistry, including access to materials, molecular targets, and synthetic strategies that are hard or even impossible to access by conventional means.

726 citations

Journal ArticleDOI
TL;DR: Mechanochemistry is becoming more widespread as a technique for molecular synthesis with new mechanochemical reactions being discovered at increasing frequency, and what more it can offer, aside from the clear benefit of reduced solvent consumption.
Abstract: Mechanochemistry is becoming more widespread as a technique for molecular synthesis with new mechanochemical reactions being discovered at increasing frequency. Whilst mechanochemical methods are solvent free and can therefore lead to improved sustainability metrics, it is more likely that the significant differences between reaction outcomes, reaction selectivities and reduced reaction times will make it a technique of interest to synthetic chemists. Herein, we provide an overview of mechanochemistry reaction examples, with ‘direct’ comparators to solvent based reactions, which collectively seemingly show that solid state grinding can lead to reduced reaction times, different reaction outcomes in product selectivity and in some instances different reaction products, including products not accessible in solution.

486 citations

Journal ArticleDOI
TL;DR: The aim of this contribution is to provide an overview of the basic concepts of mechanochemistry in relation to inorganic and organic systems.
Abstract: Mechanochemistry of inorganic solids is a well-established field. In the last decade mechanical treatment has become increasingly popular as a method for achieving selective and “greener” syntheses also in organic systems. New groups and researchers enter the field of mechanochemistry, often re-discovering many of the previously known facts and effects, while at the same time neglecting other important concepts. The author of this contribution has long been involved in mechanochemical research in both inorganic and organic systems. The aim of this contribution is to provide an overview of the basic concepts of mechanochemistry in relation to inorganic and organic systems.

458 citations

01 Nov 1993
TL;DR: In this paper, the harmonic approximation and lattice dynamics of very simple systems are discussed, and a formal quantum mechanical description of lattice vibrations is given. But it is not shown how far do the atoms move.
Abstract: Foreword Acknowledgements Definitions of symbols used 1. Some fundamentals 2. The harmonic approximation and lattice dynamics of very simple systems 3. Dynamics of diatomic crystals: general principles 4. How far do the atoms move? 5. Lattice dynamics and thermodynamics 6. Formal description 7. Acoustic modes and macroscopic elasticity 8. Anharmonic effects and phase transitions 9. Neutron scattering 10. Infrared and Raman spectroscopy 11. Formal quantum mechanical description of lattice vibrations 12. Molecular dynamics simulations Appendices Problems Bibliography Index.

441 citations

01 Jan 1971

293 citations