Swelling properties of smectite up to 90°C: In situ X-ray diffraction experiments and molecular dynamic simulations

X-ray diffraction profiles were observed using a θ–θ type goniometer with a hand-made sample chamber for controlling the vapour pressure of H2O up to the saturated vapour pressure of H2O and temperatures up to 100°C. The obtained profiles for temperatures of 50, 70 and 90°C show the nearly stepwise swelling properties at these temperatures. The transfomation P(H2O) values were determined for one to two and two to three layers of interlayer water molecules. Using molecular dynamic simulations the structural and energy properties were discussed for swelling behaviours.