Post-isomorphic substitution of trivalent metal cations for Ca2+ in portlandite crystals

摘要: Isomorphic substitution, position replacement of one cation by another similar size, leads to incorporation a variety cations into solid crystals without any significant changes the primary crystal structures. To date, isomorphic substitution has been known take place almost exclusively via co-crystallization during formation crystals. We report here discovery trivalent metal for Ca2+ ions in portlandite at room temperature as evidenced transient appearance metastable phase, Ca-based layered double hydroxides high pH, distinct shift suspension pH after phase transition, and situ topochemical reaction. This post-crystallization provides an innovative pathway synthesis materials through chemical manipulation well new insight interpretation on their weathering transformation processes.