Thermal Expansion of a Synthetic Analog of Matteuccite NaHSO4·H2O and α-NaHSO4
摘要
Abstract
The thermal behavior of aqueous sulfate NaHSO4·H2O and the product of its dehydration α‑NaHS-O4 is studied. The studies are carried out using high temperature X-ray diffraction and complex thermal analysis. Based on the data of three experiments, the temperature, nature, and sequence of phase transformations are established: NaHSO4·H2O(30–50°C) → α-NaHSO4(140–180°C) → Na2S2O7 + Na3H(SO4)2. With increasing temperature increasing in the NaHSO4·H2O structure hinge deformations occur at the level of a chain of NaO3(OH)(H2O)2 polyhedra. The anisotropy of thermal expansion is αmax/αmin = 1.9 for NaHSO-4·H2O and αmax/αmin = 1.3 for NaHSO4.