This report presents a brief discussion of the connection between high T/sub c/ superconductivity and crystal structure instability. High resolution synchrotron x-ray powder diffraction measurements have been performed on the superconductor La/sub 1.8/Ba/sub 0.2/CuO/sub 4/. These measurements show broadening of Bragg peaks, attributed to reduction of the crystal's tetragonal symmetry. This same phenomenon was observed when individual crystals were illuminated by a narrow x-ray beam. The report concludes by recommending further investigations into superconductor crystalline structure. (JDH)