Structural transformations in quartz and apatite on mechanical activation

Abstract

Methods of transmission electron spectroscopy (TEM), micro diffraction, powder X-ray diffraction (XRD), and IR spectroscopy were applied to the investigation of structural transformations of quartz and apatite subjected to mechanical treatment of varying intensity. Threshold mechanical stress equal to the theoretical shear strength was determined. This value separates the region of mechanical grinding and the region where structural and chemical transformations take place. “Liquid-crystal,” “onion-like,” and amorphous particles sized from 1 nm to 100 nm were revealed by TEM in mechanically activated quartz and apatite samples. According to electron diffraction and XRD, in “liquid crystal” quartz nanoparticles the lattice parameter of the starting matrix is preserved in one crystallographic direction, while IR spectra of the material are typical of amorphous silicic acid. Similarity of structural transformations upon indentation of single crystals of apatite and quartz, and during mechanical activation of the minerals in a planetary mill was revealed.