Funct. Mater. 2020; 27 4: 820-826.
Influence of crystal hydrate water on the process and products of heat treatment of magnesium-manganese(II) dihydrogen phosphates
National University of Life and Environmental Sciences of Ukraine, 15 Geroev Oborony Str., 03041 Kyiv, Ukraine
It has been established that crystalline water affects the change in the quantitative composition of the products and the characteristics of the process as a whole during the heat treatment of Mg1-xMnx(H2PO4)2·4H2O tetrahydrates. The maximum content of free mono- and polyphosphate acids, which are isolated in the composition of the intermediate heat treatment products during the thermolysis of tetrahydrates, is 1.6 times higher than in dihydrates with the same ratio of cations. The degree of conversion of the monophosphate anion to polyphosphate in the heat treatment products of tetrahydrates is 1.1-1.2 times greater than at the similar stages of the thermolysis of Mg1-xMnx(H2PO4)2·2H2O dihydrates. The maximum degree of polycondensation is also higher for polyphosphates in the composition of the heat treatment products of tetrahydrates (n‾ = 8 for Mg0.5Mn0.5(H2PO4)2·4H2O, n‾ = 7 for Mg0.5Mn0.5(H2PO4)2·2H2O).
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