Study of the phase transition in lithium potassium rubidium sulfate system

摘要

Specific heat, C-p, measurements have been performed in lithium potassium rubidium sulfate, (Li0.5-x/2 K0.5-x/2Rbx)(2)SO4, system in a wide range of Rb2SO4 content (x) (x = 0 up to x = 10%). Measurements were made between 300 and 800 K with special attention paid to the phase transition at 708 K. It is shown that for small contents, (x), (x = 0.2 up to x = 2%) quantitative changes in the temperature dependence of specific heat C-p(T) around the transition point, T-1, are observed. A larger content, x, results in essential changes in the critical behavior of C-p(T) and a considerable change in the phase transition accompanied by a progressive decrease in the thermodynamic parameters. The ratios of the Landau expansion coefficients change as the content of Rb2SO4 increases. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 26]