Journal of Thermal Analysis and Calorimetry, Vol. 60 (2000) 17–23
MECHANISM OF THERMAL DECOMPOSITION OF
d-METALS NITRATES HYDRATES
A. MaÓecki, R. Gajerski, S. abuí, B. Prochowska-Klisch and
K. T. Wojciechowski
Faculty of Materials Science and Ceramics, University of Mining and Metallurgy
Al. Mickiewicza 30, 30–059 Cracow, Poland
Abstract
A series of six nitrates(V) hydrates of 4d-metals as well as mercury and cadmium thermal decompo-
sition was examined by DTA, TG and EGA techniques. It was found that thermal decomposition of
d-metals nitrate(V) hydrates proceeds in three stages: partial dehydration, oxo-nitrates and hydrox-
ide nitrates formation and metal oxides formation. General chemical equations for all decomposition
stages were proposed. It was found that dehydration of hydrated salts is accompanied by partial de-
composition of nitrate(V) groups.
Keywords: DTA, EGA, d-metals, nitrates, thermal decomposition
Introduction
d-Metal nitrates hydrates are the class of substances commonly used for preparation
of high surface area materials. From this point of view the detail microscopic mecha-
nism as well as the kinetics of thermal decomposition of these salts is important to
know. There are some reports concerning decomposition of nitrates but general
mechanism of this process has not been found so far [1–3].
The goal of the work undertaken in our laboratory is to find regularities concern-
ing these reactions. In the study reported here, a series of six nitrates(V) hydrates of
4d metals as well as mercury and cadmium were investigated. Special attention will
be paid to the influence of cation ability to change its oxidation state on the mecha-
nism of thermal decomposition.
Experimental
Results presented in this work are based on earlier investigations on decomposition of
Cr(NO
3
)
3
·9H
2
O, Co(NO
3
)
2
·2H
2
O and Ni(NO
3
)
2
·2H
2
O [4, 5]. Additionally preliminary
investigations on decomposition of the following nitrates were made: Fe(NO
3
)
3
·6H
2
O,
Cu(NO
3
)
2
·2.5H
2
O, Zn(NO
3
)
2
·6H
2
O, Cd(NO
3
)
2
·4H
2
O and Hg(NO
3
)
2
·nH
2
O [6–8]. Com-
pounds used in experiments were commercial, pure for analysis.
1418–2874/2000/ $ 5.00
© 2000 Akadémiai Kiadó, Budapest
Akadémiai Kiadó, Budapest
Kluwer Academic Publishers, Dordrecht