Intermittent motion of a twin boundary in

¹ Graduate School of Science, Hokkaido University - Sapporo 060-0810, Japan
² Faculty of Information Media, Hokkaido Information University Ebetsu 069-8585, Japan

Corresponding author: kaw@sci.hokudai.ac.jp

Received: 28 April 2003
Accepted: 25 July 2003

Abstract

We observe the intermittent motion of a single planar twin boundary under a constant shear stress in organic crystals . The boundary is forced to shuttle repeatedly in a specific region of a single crystal. For each move we measure the residence time at a certain trap as well as the local velocity in the vicinity of the trap. We find that varies largely on every move even under a well-controlled constant stress, while is almost constant. This wide distribution of can be well characterized by a lognormal function. The autocorrelation of series exhibits apparently an exponential decay. To reveal the mechanism of the boundary motion we examine the temperature dependence of and find the boundary driven by thermal activation. On the other hand, the shear stress dependence of , an effective velocity at the trap, is found similar to that of . The result indicates that the boundary does not make a complete stop at the trap but creeps very slowly. We also propose a phenomenological description for the characteristic feature of .