Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6660483 | The Journal of Chemical Thermodynamics | 2015 | 10 Pages |
Abstract
We report enthalpies of formation from the elements and oxides, ÎfH° = â(22,673.44 ± 30.19) kJ·mol-1 and Îf,oxH = â(869.68 ± 28.75) kJ·mol-1, for [GeO4Al12(OH)24(H2O)12](SeO4)4·12H2O(cr) (GeAl12) measured using high temperature oxide-melt solution calorimetry. This material is the selenate salt of the germanium-substituted polynuclear Al137+ ion in the ε-Keggin structure. We also report heat capacities from temperatures of (2 to 300) K on this GeAl12 selenate and its other heterometal substituted forms, Na[AlO4Al12(OH)24(H2O)12](SeO4)4·12H2O(cr) (AlAl12) and Na[GaO4Al12(OH)24(H2O)12](SeO4)4·12H2O(cr) (GaAl12), measured using a Quantum Design Physical Property Measurement System (PPMS). These measurements were used to calculate entropies and subsequently free energies of formation for these three materials. All three MAl12 selenates, where M = Al(III), Ga(III), or Ge(IV), have similar heat capacities from temperatures (2 to 300) K and similar characteristic Debye temperatures, ÎD, suggesting similar lattice vibrational densities of states.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Dana Reusser, Jacob Schliesser, Brian F. Woodfield, Alexandra Navrotsky,