Describing faulting in LDH using a layer group approach

Layered double hydroxides (LDH) are a type of layered inorganic clay structure where positive brucite-like layers with partial trivalent cationic substitution are interleaved with charge-balancing anions (Fig. 1). There are a wide variety of compatible anions that can be substituted into the interlayers of LDH materials, and cationic substitution into the brucite-like layers of alkali, alkaline earth, rare earth, and transition metals have been reported1. This huge compositional range and accommodating interlayer provide a great opportunity to engineer materials with novel properties, and recent work with these materials show an enormous potential in the areas of catalysts or catalyst supports, selective chemical nano-reactors processing, separation membrane technology, filtration, controlled anion release and anion scavenging2. Yet the structural characterization of such materials by X-ray diffraction is not straightforward: many of these materials exhibit stacking faults and extended 1-dimensional disorder due to weak interlayer bonding, which leads to the appearance of diffuse intensity in reciprocal space that, so far, is extremely difficult to model.