This study reports experimental investigations by non-isothermal TG/DSC
analysis of Zn(NO3)24H2O,
and their mixtures of known compositions in the temperature range 30–1200C.
Solid/liquid transitions in the sealed samples of the hexahydrate salts and
their mixtures were also studied by DSC in the temperature range 0–60C.
The mixture with composition 0.85Zn(NO3)26H2O+0.15Cu(NO3)26H2O showed single
melting peak at 29C. This mixture was chosen for detailed studies. Melting
temperature and heat of fusion of single salt hexahydrates and of the mixture
were calculated from DSC endotherms.
The different stages in the
thermal decomposition processes have been established. The intermediate and
the final solid products of the thermal decomposition were analyzed by XRD.
The scheme and the decomposition temperature depended on the composition of
the starting material. The final decomposition products were CuO (monoclinic),
Cu2O (cubic), ZnO (hexagonal) and their mixtures with
the defined crystalline structures. Possible influence of the addition of
CuCl22H2O into the mixture
0.85Zn(NO3)26H2O+0.15Cu(NO3)26H2O and a gel combustion technique of the
precursor preparation, on the composition and morphology of the solid decomposition
products, were also studied. The gel combustion technique, using citric acid
added to a mixture of 0.85Zn(NO3)26H2O+0.15Cu(NO3)26H2O, was applied
in an attempt to obtain mixed Zn/Cu oxides of a particular mole ratio. The
morphology of the solid decomposition products was examined by SEM.