Deaquation process in ammonium Tutton salts through electrical and dielectric measurements

Abstract

The d.c. electrical conductivity (σ), dielectric constant (g3′) and thermogravimetric analysis studies are reported in the temperature range 20–280°C for zinc ammonium sulphate hexahydrate and magnesium ammonium sulphate hexahydrate Tutton salts. The results are attributed to the release of water molecules at the respective dehydration temperatures and the dissociation of a fraction of such released water molecules into H+ and OH− ions. The dissociation energies of four equatorial and two axial H2O molecules in both the systems have been calculated. The difference in the dissociation energy values have been attributed to the distortions of M(H2O)6 octahedra. Results obtained for an isomorphous potassium Tutton salt, zinc potassium sulphate hexahydrate are also included.