An internal stress pattern in free standing films

We report a sinusoid appearance of cracks existing in a continuous nickel (Ni) film system deposited on silicone oil surfaces. The sinusoid cracks start from the sample edges or from other cracks, then their oscillatory amplitudes decrease gradually as they extend and finally disappear. One crack may bifurcate into two or three cracks, or two cracks may coalesce harmoniously. The sinusoid appearance of the cracks represents a sinusoid stress pattern in the Ni films, which mainly results from the characteristic boundary condition and interactions among the atoms in these free sustained films. (C) 2003 Elsevier Science B.V. All rights reserved.