For time-resolved diffraction studies under high temperature and/or high pressure, we designed a new diffractometer incorporating a curved position sensitive detector and tested the rapid intensity measurement and the resolution of the angular dispersive diffraction. The diffraction profiles were compared with those from energy dispersive diffraction. Rapid intensity collection has been carried out with a CAMAC module. A curved position sensitive detector with a 120° working angular region was installed on the off-centered four circle diffractometer. Only a few seconds were needed to obtain a whole powder diffraction because of the extremely high counting efficiency due to the streamer mode.
Time-resolved observations of the dehydration reactions of Mg(OH)2 and Ca(OH)2, have been undertaken by angular dispersive and energy dispersive x-ray powder diffraction at high temperature. The in situ observations of the dehydration process provide kinetic information, such as the reaction rate, the apparent activation energy and the dehydration mechanism.