In situ generation of metal clusters in interlamellar spacing of montmorillonite clay and their thermal behaviour

Intercalated Ni–Ni(CH3COO)2–montmorillonite (I), Ni0–montmorillonite (II), Zn–Zn(CH3COO)2–montmorillonite (III) and Zn0–montmorillonite (IV) composites have been synthesised and their thermal behaviour is studied by TG, DTG and DTA substantiated by XRD and TEM. The endothermic DTA peaks of the composites I–IV due to dehydration and dehydroxylation, in general, occur at lower temperature compared to those of untreated Na–montmorillonite. The phase change of the clay matrix for the composites I and II takes place at slightly higher temperature compared to Na–montmorillonite, while for the composites III and IV it occurs at lower temperature. XRD data show that the basal spacing (d0 0 1 value 13.7 Å) of the intercalated metal cluster composite II is higher than that of the composite IV (d0 0 1 value 12.8 Å) at about 300 °C revealing intercalated metal cluster of size 4.1 and 3.2 Å, respectively. TEM study shows that the particle size of the metals for the composite II is in the range of about 0–80 nm while for the composite IV, the size range is about 0–30 nm. Therefore, bigger sized metal nanoparticles (>0.41 nm) are not present in the interlamellar spacing of the clay.