Mechanochemically assisted synthesis of pristine Ca(II)Sn(IV)-layered double hydroxides and their amino acid intercalated nanocomposites

Syntheses of Ca(II)Sn(IV)-layered double hydroxides (LDHs) are attempted by the traditional co-precipitation as well as mechanochemical methods. Both the co-precipitation method and the one-step milling operation proved to be unsuccessful; these methods only produced physical mixtures of hydroxides and carbonates of the two metal ions. However, a two-step milling operation (dry milling followed by milling in the presence of minute amount of water) led to successful synthesis, verified by a range of characterisation methods. Surprisingly, it was found that ball-milling was not even necessary; the reaction proceeded on manual grinding of the components in an agate mortar with a pestle. The preparation of nanocomposites through intercalation of the anions of cystine or valine into Ca(II)Sn(IV)-LDH could also be achieved by the two-step milling method verified again by a range of instrumental methods.