Abstract
Structure analysis of a natural chabazite was conducted at 123 K using single crystal X-ray diffraction. We have observed that in one of water sites, the electron density distribution, which seemingly has one peak at room temperature, is clearly separated into the two peaks at 123 K because of the reduction of atomic thermal vibrations. Thus, we have revealed that this water site is located at the different Wyckoff position from the previously assigned position. The refined occupancies show that the crystal was partially dehydrated by a continuous flow of dry cold N2 gas introduced in the intensity measurements at low temperature. This partial dehydration provides important knowledge of the site preference for dehydration and the cation migration with dehydration, from comparison with the occupancies at room temperature with full hydration.
