TG and EGA investigations of the decomposition of some metal ammonium phosphate monohydrates by means of the Derivatograph under conventional and quasi-isothermal — Quasi-isobaric conditions

The thermal decomposition of MgNH₄PO₄·H₂O, MnNH₄PO₄ · H₂O, CoNH₄PO₄ · · H₂O and CdNH₄PO₄·H₂O were investigated under conventional and under quasiisothermal-quasi-isobaric conditions. The experiments were carried out with a Derivatograph suitable for performing simultaneous TG and EGA examinations. It was found that the thermal decompositions of the four compounds each consist of two partial processes: the departure of the water of crystallization, and the subsequent inseparable escape of the ammonia and constitution water. Depending on the experimental conditions, the two processes more or less overlap. The relatively best separation of the two processes can be attained by using quasi-isothermal and quasi-isobaric conditions.