X-ray topographic investigation of quartz single crystals at high temperature, up to 1185 degrees C

Real time experiments were performed to study the structural behaviour of m onocrystalline quartz at high temperatures. White beam diffraction topograp hy in transmission geometry was used. A creation of Dauphine-twins took pla ce slightly below the alpha-beta-phase transition temperature. The diffract ion contrast of twins and temperature stresses disappeared above the alpha- beta-phase transition temperature. Up to 1185 degrees C neither changes of the defect structure nor a creation of new defects were observed. A. precur sor for a beginning of a reconstructive phase transition from quartz to cri stabolite could not be observed within a time interval of 2h at 1180 degree s C.