Mechanochemical Synthesis of Nanocomposites with Specified Composition in the Presence of a Solvent for Precursors

Abstract

The objective of this work is an attempt to introduce into scientific practice the method of “mechanochemical recrystallization” in solid-phase systems with small additives of a liquid solvent. Dimethyl sulfoxide (DMSO), a universal bipolar aprotic solvent, has been used as the additive. As an example, the mechanical activation of reaction AgNO₃ + NH₄I + z NH₄NO₃ (diluent) + yS + xDMSO = AgI + yS* + (z+1)NH₄NO₃ + xDMSO has been studied, where z ≈ 5, y ≈ 1, and x \( \ll \) 1 are molar fractions. The formation of sulfur (S*) and silver iodide (AgI) nanoparticles has been revealed, and/or S*/AgI nanocomposites with controlled contents of the components have been synthesized. The use of NH₄NO₃, which is a non-target product of the mechanosynthesis, as a diluent leads to the stabilization of nanoparticle sizes. The nanoparticles are formed in the medium of DMSO due to the conventional recrystallization (continuous process of dissolution–crystallization of sulfur) or the reactional recrystallization (process of dissolution of AgNO₃ and NH₄I followed by their interaction with the AgI crystallization) rather than the direct mechanical activation. The former and latter mechanisms are realized when obtaining S* and AgI, respectively. The target products (S*, AgI, and S*/AgI) are purified from water-soluble components (NH₄NO₃, DMSO) by washing in an ultrasonic bath. The proposed technical solution of the problem has been realized in planetary ball mills with different milling tools.