Thermoanalytical investigations on the decomposition of double salts: Part II. The decomposition of double salts MeCl · MgCl2 · 6H2O (Me = NH4, Rb, Cs)

Abstract The melting and decomposition behaviour of double salts MeCl · MgCl 2 · 6H 2 O (Me = NH 4 , Rb, Cs) has been investigated in a closed system under dynamic heating conditions and in open systems under dynamic and quasi-isothermal and quasi-isobaric conditions in the temperature range 20–300° C. DTA heating and cooling cycles in the closed system illustrate the melting behaviour of the double salts. Thermal decomposition of the salts under quasi-isothermal and quasi-isobaric conditions occurs at pressures of 115 kPa from the melt (with the exception of rubidium carnallite) and under reduced pressure (~ 5 kPa) from the solid. In all cases dihydrates are stable intermediate products. Further thermal decomposition is accompanied by hydrolysis and basic products are formed.