THERMAL TRANSFORMATIONS OF MG(H2PO4)(2).4H(2)O

Isothermal and non-isothermal transformations of Mg(H2PO4)(2) . 4H(2)O in vacuum, water vapour, dry and humid air atmosphere at 20-900 degre es C were studied by the methods of DTA, XRD, paper chromatographic an alyses, gravimetry and optical microscopy. It has been shown that the size of initial tetrahydrate crystals and the composition of gaseous p hase affect not only the dehydration rate but the chemical and phase c omposition of the resulting intermediates as well. At the same time, t he crystalline polyphosphate [Mg(PO3)(2)](n) is the end product, irres pective of the heat-treatment conditions. (C) 1998 Elsevier Science B. V.