DETERMINATION OF THE DISSOLUTION SLOWNESS SURFACE BY STUDY OF ETCHED SHAPES .2. COMPARISON OF 2D EXPERIMENTAL AND THEORETICAL ETCHING SHAPES

The anisotropic etching behavior of quartz crystal in concentrated amm onium bifluoride solution is studied and analyzed in the framework of a tensorial model. This model allows to simulate bi- or three-dimensio nal etching shapes from the equation for the representative surface of the dissolution slowness. In this paper, we present experimental resu lts such as surface profile and initially circular cross-sectional pro files of differently singly- or doubly-rotated cuts. The polar diagram s of the dissolution slowness vector in several planes are deduced fro m experimental data. The comparison between predicted surface and cros s-sectional profiles and experimental results is detailed and shows a good agreement. In particular, several examples give evidence that the final etched shapes are correlated to the extrema of the dissolution slowness. Ho Never, in several cases, experimental shapes cannot be si mply correlated to the presence of extrema. Simulation gives effective ly evidence for an important role play-ed by more progressive changes in the curvature of the slowness surface. Consequently, analysis of da ta merits to be treated carefully.