Thermal decomposition of Prussian blue analogues in various gaseous media

Prussian blue analogues with formulae Ni3[Co(CN)6]2·16H2O(I), Cu3[Co(CN)6]2·17H2O(II), Ni3[Fe(CN)6]2·15H2O(III) and Cu3[Fe(CN)6]2·13H2O(IV) have been synthesized. The thermal decomposition of all complexes in oxidizing (air), reducing (hydrogen) and inert (argon) atmospheres was studied in the temperature range from 20 to 1000 °C. TG–DSC curves were obtained; analysis of solid thermolysis products was performed. It was established that the decomposition process of all the studied compounds in air ends up to 450–500 °C, and mass loss continues up to 1000 °C in argon. Solid products of thermolysis are oxides of central ions (NiO, CuO, Co3O4, Fe3O4) in air; mixtures of metals or Ni3Fe (III) in argon; Ni and Co (I) and Ni3Fe + Fe(III), and mixtures of Cu + Co (II) and Cu + Fe(IV) in hydrogen. Hexacyanocobaltates are reduced at lower temperatures and more fully than hexacyanoferrates under the same conditions.