X-ray diffraction pattern simulation for thermally treated [Zn-Al-Cl] layered double hydroxide

Thermal analyses and X-ray diffraction (XRD) were combined with refinement and simulation of the XRD patterns in order to elucidate the evolution of the atom distribution in the interlayer domain of the [Zn-Al-Cl] layered double hydroxide during heating, Rietveld refinement indicates that the structure is composed of [Zn1-xAlx(OH)(2)](0.33+) layers separated by water molecules and chloride ions. Zn and Al are randomly distributed among the octahedral positions. The OH layer sequence is -BC-CA-AB-BC-. Oxygen of water molecules and chloride ions, also randomly distributed, prefer positions at about 0.76 Angstrom of the threefold axis, The simulation of the XRD patterns shows that these positions were imposed by geometric constraints of water molecules connecting two OH groups of adjacent brucite-like layers. (C) 2000 Academic Press.