Formation and hydration enthalpies of the hydrosodalite family of materials

Eric C. Moloy, Qingyuan Liu, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The four end-member structures of the hydrosodalite family of materials (Na6+x(OH)x[Al6Si6O 24](H2O)N) are synthesized via hydrothermal techniques and characterized using X-ray diffraction, thermal analysis, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. High-temperature drop-solution calorimetry in molten 2PbO • B2O3 at 975 K is used to measure the formation and hydration enthalpies. We report the formation enthalpies, from both the oxides and the elements, for a total of eight samples, two for each end-member. The average formation enthalpy (from oxides) is -88.1 ± 1.0 kJ/mol-TO 2 for basic sodalite{ideally Na8(OH)2[Al 6Si6O24](H2O)4},-79.6 ± 1.2 kJ/mol-TO2 for hydroxysodalite{ideally Na 8(OH)2[Al6Si6O24]},-68.0 ± 1.1 kJ/mol-TO2,for hydrosodalite{ideally Na 6[Al6Si6O24](H2O) 8},and -54.9 ± 1.1 kJ/mol-TO2, for sodalite{ideally Na6[Al6Si6O24]}.The corresponding average hydration enthalpies are -76.7 ± 5.3 kJ/mol-H2O and -37.0 ± 2.4 kJ/mol-H2O for the Na8 and Na6 series, respectively.

Original languageEnglish (US)
Pages (from-to)283-292
Number of pages10
JournalMicroporous and Mesoporous Materials
Issue number1-3
StatePublished - Jan 21 2006
Externally publishedYes


  • Formation enthalpy
  • Hydration enthalpy
  • Hydrothermal synthesis
  • Sodalite
  • Zeolite

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials


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