Notes a Simple Diffractometer Heating-cooling Stage: Application to the Study of an Organo-clay Complex

The study of the intercalation of organic compounds into clays, as in the preparat ion of pillared clays, is of great importance both from the theoretical point of view and for its applications in pharmacy, agriculture, clay characterization, catalysis, etc. (MacEwan and Wilson, 1980; Theng, 1974; Pinnavaia, 1983). At different temperatures, intercalated organic molecules, especially long-chain molecules, can undergo reversible phase transitions, and hydratable cations can hydrate to different degrees. These phenomena can be followed by studying the variat ion in X-ray powder diffraction (XRD) basal spacing with temperature (Brindley and Ray, 1964; Lagaly and Weiss, 1971; Pfirrmann et al., 1973). Although various temperature-control stages for powder X-ray diffractometers have been described in the literature (Brown et aL, 1972; Lagaly et aL, 1975; Morandi et al., 1976-1977), the advantage of the system described here is that XRD patterns can be obtained more simply and quickly for temperature ranges both below and above ambient room temperature and with greater temperature stability, due to the simultaneous use of cold and heat sources.