• Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

    • Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/boms/043/0141

    • Keywords

       

      Layered double hydroxide; aluminium hydroxide; perchlorate; sulphate.

    • Abstract

       

      Imbibition of lithium sulphate into aluminium hydroxide is known to result in a sulphate-intercalated layered double hydroxide (LDH) of Li and Al. The perchlorate ion has the same size and molecular symmetry as the sulphate ion,but only half its charge. Consequently, twice the number of ClO$^−_4$ ions is needed to balance LDHs the charge on the metal hydroxide layer, compared to the SO$^{2−}_4$ ions. In this work, the ClO$^−_4$-intercalated LDHs were obtained from both the bayerite and gibbsite precursors. Inclusion of the hydration sphere along with the ClO$^−_4$ anion, induced turbostratic disorder in the stacking of the metal hydroxide layers. Temperature-induced dehydration ($T \sim 100$–140$^{\circ}$C) brought about a partial ordering in the interlayer region and the ClO$^−_4$ ion oriented itself with one of its $C_2$-axes parallel to the metal hydroxide layer. The close packing of ClO$^−_4$ ions could be realized by the complete dehydration of LDH and the distribution of the ClO$^−_4$ ions in all the available interlayer sites. In contrast, within the crystal of the sulphate analogue, the sulphate ions occupy only half the number of interlayer sites. The other half is occupied by the residual water molecules, as the sulphate analogue does not fully dehydrate even at elevated temperatures. This difference in the behaviour of the two LDHs has its origin in the largedifference in the hydration enthalpies of the two anions.

    • Author Affiliations

       

      LATHA PACHAYAPPAN1 P VISHNU KAMATH1

      1. Department of Chemistry, Central College, Bangalore University, Bangalore 560 001, India
    • Dates

       
    • Supplementary Material

       
  • Bulletin of Materials Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.