Features of Relaxation Parameters of Different Types of Quartz during Dynamic Nanoindentation

This study examined various types of SiO2 crystals: single-crystal (α-SiO2), polycrystalline (p‑SiO2), and amorphous (glassy) (a-SiO2) ones so as to find out the influence of a structural form on changes in relaxation parameters during dynamic nanoindentation. For all studied samples, relaxation parameters were found to depend on the sample type and exhibit a consistent increase with increasing of indenter load. A detailed study of the relaxation parameters (he, he-p, and hres) allowed the authors to determine the mechanisms of plastic deformation of different quartz types during nanoindentation. Computer visualization of the surface topography around the indentations confirmed the involvement of the rotational-translational deformation mechanism of different types of SiO2 crystals in the formation of hardness indentations. It is shown that the rotational mechanism makes a greater contribution to quartz indentation in the low-load range (P = 10–50 mN), while the contribution of the translational mechanism increases with load increasing (P = 100–500 mN) and during the transition in the series α-SiO2 → p-SiO2 → a-SiO2.