Rim formation on crystal faces growing in confinement

• Published in: Journal of crystal growth Vol. 346; no. 1; pp. 89 - 100
• Main Authors: Røyne, Anja, Dysthe, Dag Kristian
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2012; Elsevier
• Subjects: A1. Crystal morphology; A1. Stresses; A1. Supersaturated solutions; A1. Surface processes; A1. Surface structure; Concentration gradient; Confining; Cross-disciplinary physics: materials science; rheology; Crystal growth; Crystal surfaces; Crystals; Density; Exact sciences and technology; Growth from solutions; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Steady state; Stresses; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; A1. Surface processes; A1. Supersaturated solutions; A1. Crystal morphology; A1. Stresses; A1. Surface structure; Crystal growth; Confinement; Roughness; A1Supersaturated solutions; Steady state; A1Surface structure; Experimental result; A1Stresses; Morphology; Growth mechanism; A1Crystal morphology; Crystal growth from solutions; Stress effects; A1Surface processes; Crystal faces; Concentration distribution; Concentration gradient
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.03.019

A crystal face growing from solution while exerting a normal force on a confining surface is often observed to develop a growth rim surrounding a hollow core. The interpretation has been that this is a manifestation of steady state growth due to the balance between the concentration gradient and stress gradient along the confined crystal surface. In this paper, we present experimental results which show that the growth rim is instead formed as a consequence of faceted growth on the confined surface. Steady state growth is not ensured by a gradient in normal stress, but rather a gradient in step density along the crystal face. The loaded crystal surfaces display a high degree of roughness, and the stress is not uniformly distributed across the surface, but transmitted at discrete asperities. We discuss the implications of these findings for the interpretation of previous experimental results, and for the thermodynamics of crystal growth subject to normal stress. ► Single crystal of NaClO3 subject to a normal load have been grown. ► A distinct growth rim is observed and measured on the confined crystal surfaces. ► We show that the rim is formed due to anisotropic growth in a confined geometry. ► Our findings contradict the prevailing hypothesis of stress driven transport.