Thermal Decomposition of Lanthanum O-Hydroxybenzoate and O-Bromobenzoate

Abstract

The conditions of thermal analysis of Lanthanum -O-Hydroxybenzoate and
Lanthanum -O-Bromobenzoate were studied .
The Hydrated complexes lose water of crystallization in two steps . Lanthanum -OHydroxybenzoate
starts to lose water of crystallization between (60-230)oC , but
Lanthanum -O-Bromobenzoate loses water of crystallization between (100-320)oC .
The intermediate products La2O3(OHC6H4COO)5 and La2(BrC6H4COO)6 were
obtained by heating the two complexes at(320-350)oC and (320-380)oC respectively . In
the fourth step , anhydrous structures of the complexes decomposed in one step and then
were transformed to La2O3 . These results are using TG,DTG,DTA,IR and (X – ray)
diffraction techniques . DTA curves revealed exothermic peaks for the decomposition
steps , but endothermic peaks were obtained from the dehydration of complexes