Rietveld Refinement of Interlayer Structure

When sufficiently large, defect-free single crystals of a material are available, its structure can be precisely determined by X-ray diffraction. Unfortunately, most LDHs are only available in the form of fine crystallites, and this is generally not possible. 

Geometrical considerations suggest that for chloride ions, OH-Cl-HO 

Rietveld reflnement of analogous [M4Cr2(0H)i2]Cl2 4H20 (M = Zn, Cu) materials suggest that the chloride ions also occupy 18( ) sites with the water molecules disordered over 18(g) (M = Zn) or 36(i) (M = Cu) sites [25]. It 

Rietveld refinements of the structures of Mg Al - CO3 LDHs (n = 2.0, 5.0) have been reported [39]. The oxygen atoms of both carbonate ions and water molecules were found to occupy a single set of 18(fi) sites distributed aroimd the three-fold O- 0 axis with a 3Ri polytype stacking (space group R5m). 

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