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

Chem. Met. Alloys 7 (2014) 9-14

https://doi.org/10.30970/cma7.0236

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 Zn_2-xCo_xP₂O₇∙5H₂O (0 ≤ х ≤ 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-Zn_2-xСо_xP₂O₇ (0 ≤ х ≤ 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-Zn_2-xСо_xP₂O₇ is formed by solid-phase reaction of partial dehydration products. A general scheme of the solid-phase thermal transformations of Zn_2-xСо_xP₂O₇∙5H₂O (0 ≤ х ≤ 0.69) is proposed.

Reaction scheme for the dehydration of Zn_1.31Со_0.69Р₂O₇∙5H₂O

Keywords

Thermolysis / Thermal dehydration / Destruction / Diphosphates