The solid state phase transformation of potassium sulfate

• Published in: Solid state communications 2007-03, Vol.141 (9), p.497-501
• Main Authors: Bin Anooz, S., Bertram, R., Klimm, D.
• Format: Article
• Language: English
• Subjects: A. Dielectrics; B. Crystal growth; Condensed matter: structure, mechanical and thermal properties; D. Phase transitions; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Physics; Solid-solid transitions; Specific phase transitions
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2006.12.008

Potassium sulfate single crystals that are grown from aqueous solutions lose, upon the first heating, up to 1% of mass that is assumed to be water. This mass loss occurs in the vicinity of the PT from orthorhombic to hexagonal K 2SO 4. Only in the first heating run of K 2SO 4 that has not yet released water, pretransitional thermal effects can be observed in the DTA curve. If K 2SO 4 crystals are grown from solutions containing 4 wt% Cd, Cu, or Fe, only Cu or Fe can be incorporated significantly with concentrations of several 0.1%. The phase transformation temperature measured for such solid solutions depends on the heating rate. For pure K 2SO 4, the phase transformation temperature is independent of heating rate 581.3  ∘C and the enthalpy of transformation is (5.8±0.2) kJ/mol.