9730304 Petrenko This project addresses photoplasticity, dislocation motion and interaction in II-VI materials. Most of the research will be conducted with CdS and ZnSe with emphasis on identifying and developing greater understanding of the physical mechanism of the x-ray plastic effect (XPE). Under certain conditions, this phenomenon can cause significant material hardening, for example causing a doubling of yield stress and a decrease in rate of plastic deformation by two to four orders of magnitude. In these studies, this effect will be used as a tool to study mechanisms of dislocation motion. %%% The project primarily addresses research issues in materials physics. The research will contribute basic knowledge at a fundamental level to a somewhat narrow, but unique phenomenon observed when materials are exposed to X-rays. The basic knowledge and understanding gained from the research may contribute to improving the performance and stability of advanced devices such as blue lasers and light emitting diodes (LEDs). ***