HYDRATION BEHAVIOR OF NA-SMECTITE CRYSTALS SYNTHESIZED AT HIGH-PRESSURE AND HIGH-TEMPERATURE

Hydration behavior of Na-smectite crystals synthesized at a pressure o f 5.5 GPa and temperatures of 1400-degrees-1500-degrees-C was examined by X-ray powder diffraction at various relative humidities (RH) in th e range of 0-100%. The basal spacing of the Na-smectite crystal increa sed stepwise with increase in RH. The reflections observed were only n ormal reflections of a single or dual hydration states of smectite. No irrational, intermediate, or asymmetrical reflections were observed. The simple hydration behavior, not known for natural smectite with fin e particle sizes and low crystallinity, indicates that the Na-smectite crystals are as perfect as common inorganic crystals with an ordered structure.