Thermal solid-phase transformations of hydrated Zn-Co(II) diphosphates

 

Chem. Met. Alloys 7 (2014) 9-14

 

N.M. ANTRAPTSEVA, N.V. SOLOD, L.B. KOVAL, T.S. GRYSYUK

 

The sequence of physico-chemical and structural transformations occurring during the thermolysis of the solid solution of diphosphates of composition Zn2-xCoxP2O7∙5H2O (0 ≤ ≤ 0.69) has been established. The composition, temperature ranges of formation and the thermal stability of the products of partial and complete dewatering have been determined. The final thermolysis product, the solid solution of anhydrous diphosphates α-Zn2-xxP2O7 (0 ≤ ≤ 0.69), has been identified. It is shown that the formation proceeds via two routes. The first route consists in thermal dehydration of the original diphosphate (up to 57-63 %). Along the second route, up to 43-37 % α-Zn2-xxP2O7 is formed by solid-phase reaction of partial dehydration products. A general scheme of the solid-phase thermal transformations of Zn2-xxP2O7∙5H2O (0 ≤ ≤ 0.69) is proposed.

 

 

Reaction scheme for the dehydration of Zn1.310.692O7∙5H2O

 

Keywords

Thermolysis / Thermal dehydration / Destruction / Diphosphates