The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

In this study, hen eggshell (ES) biomaterial was treated by two mechanochemical methods. Here we show that using of low-current high-voltage electrical impulses during electrical discharge assisted mechanical milling (EDAMM) or high-energy milling (HEM) are proper tools for ES transformation to materials suitable for the further applications. The decomposition of calcite CaCO₃ (the main component of ES) into lime CaO (EDAMM treatment) or calcite-aragonite transformation (HEM treatment) were documented by X-ray diffractometry. The applied techniques bring about solid state transformation, high degree of calcite amorphization, and enhancement of specific surface area of ES samples. As examples of using the transformed ES the uptake of cadmium ions during sorption experiments and the dechlorination of polyvinyl chloride are given. In both cases, the technologically accepted recoveries and kinetics have been obtained.

In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite Cu₂FeSnS₄/rhodostannite Cu₂FeSn₃S₈ (CFTS) via mechanochemical route using Cu, Fe, Sn and S elements as precursors in one-pot experiments. Methods of X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were applied to characterize properties of the unique nanostructures. Mechanochemical route of synthesis induced new phenomena like explosive character of reaction, where three stages could be identified and the formation of nanostructures 5–10 nm in size. By using XPS method, Cu(I), Fe(II), Sn(IV) and S(-II) species were identified on the surface of CFTS. The value of optical band gap 1.27 eV is optimal for semiconductors applicable as absorbers in solar cells. The significant photocatalytic activity of the CFTS nanocrystals was also evidenced. The obtained results confirm the excellent properties of the quaternary semiconductor nanocrystals synthesized from earth-abundant elements.