Surface Structure of α-Quartz*

Crystalline silica (SiO₂) surfaces play an important role in nature and technology, and are often used as substrates in scientific studies. Despite its importance, the atomic surface structure of quartz still remains poorly understood, especially on the experimental side. Here we present a real space structure study of α-quartz(0001) surfaces prepared at high temperature in air. The preparation approach is highly reproducible and leads to well-defined, flat, and clean terraces in ambient conditions. Using high-resolution atomic force microscopy (AFM), we observed a large scale surface termination with a reconstruction periodicity of 5 nm, consistent with previous literature [1,2]. By characterizing the samples with AFM in humid air, dry nitrogen, and water we establish deeper insight into surface morphology and reconstruction. Using the enhanced resolution capabilities of atomic force microscopy in liquid water, we address the real space atomic scale structure of this surface and find that the lattice dimensions agree with the bulk crystal lattice constants for α-quartz.
[1] Bart, F. & Gautier, M. Surf. Sci. 311, L671–L676 (1994).
[2] Eder, S. D. et al. Sci. Rep. 5, 14545 (2015).