Atomic force microscopy observations of hollow cores on the {1 1 1} and {10 0} faces of barium nitrate

The centers of several growth spirals on. the dominant {1 1 1} and {1 0 0} faces of Ba(NO3)(2) crystals grown from aqueous solutions were investigated using ex situ atomic force microscopy. On both faces, often hollow cores w ere observed, at the outcrops of dislocations with Burgers vectors b = < 1 0 0 > on the {1 0 0} face, and b = < 1 0 0 >, < 1 1 0 > and (1 1 1) on the (1 1 1) face. The occurrence of the hollow cores depends on the supersatura tion. For the (1 1 1) face, the dependence of the hollow core radius on the Burgers vector is measured. This observed dependence is less strong than t he quadratic dependence expected from the Frank radius, which is explained by the influence of the supersaturation. Apart: from that, recombination of two dislocations, leaving the hollow cores on the original positions has b een observed. (C) 1999 Elsevier Science B.V. All rights reserved.