The Structure of the α-quartz (0001) Surface Investigated Using Helium Atom Scattering and Atomic Force Microscopy

W. Steurer (1) , A. Apfolter (1) , M. Koch (1) , Thomas Sarlat (2) , E. Sondergard (2) , W.E. Ernst (1) , B. Holst (1)

1 Institute of Experimental Physics [Graz]
2 SVI - Surface du Verre et Interfaces

In this paper we present the first structural investigation of quartz using helium atom scattering (HAS). Studies were carried out on the alpha-quartz (0001) surface (Z-cut). He-diffraction experiments reveal a complex hexagonal diffraction pattern. Prominent peaks are visible at positions corresponding to the periodicity of the bulk unit cell (4.90±0.02 °A). In addition weak (2×2) peaks and satellite peaks are observed. Two recent theoretical papers both propose a (1 × 1) reconstruction for alpha-quartz (0001) with 120° symmetry for the surface unit cell: the so called dense structure. We propose a model where terraces with step heights of a multiple 1/3 of the unit cell height lead to domains rotated by ±60° relative to each other. This is supported by AFM images. The satellite peaks indicate an incommensurate super-lattice structure with a periodicity of the order of 57 °A, presumably related to strain relief mechanisms. The (2 × 2) peaks may stem from co-existing regions of a semi-dense structure, which is predicted to have a higher energy than the dense, (1 × 1) phase.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

W. Steurer, A. Apfolter, M. Koch, Thomas Sarlat, E. Sondergard, et al.. The Structure of the α-quartz (0001) Surface Investigated Using Helium Atom Scattering and Atomic Force Microscopy. 24th European Conference on Surface Science (ECOSS-24), Sep 2006, Paris, France. pp.4407-4411. ⟨hal-00504494⟩