Mircea Stefanescu,1 Marcela Stoia,1 Thomas Dippong,1 Oana Stefanescu1 and Paul Barvinschi2
1 Faculty of Industrial Chemistry and Environmental Engineering, University
“Politehnica”of Timisoara, P-ta Victoriei nr. 2., 300006, Timisoara, Romania
2 Faculty of Physics, West University of Timisoara, Bv. V. Parvan no. 4,
300223 Timisoara, Romania
* Corresponding author: E-mail: mircea.stefanescu@chim.upt.ro
Abstract
This paper presents a study on preparation of the oxydic system CoxFe3–xO4 (x =
0,5; 1,0; 1,5) as nanoparticles starting
from metalic nitrates (Co(NO3)2 · 6H2O, Fe(NO3)3 · 9H2O) and diols: 1,2
propanediol (OHCH2CH(OH)CH3) and 1,3
propanediol (OH(CH2)3OH). During the heating of metal nitrates – diol solution,
a redox reaction took place between
NO3 – anion and polyol, when –CH2–OH was oxidized at –COO–. The carboxylate anions,
which resulted in the redox
reaction, reacted with Co(II) and Fe(III) cations to form coordinative
compounds, that were used as precursors for the
CoxFe3–xO4 oxide system.
DTA curves of the solutions Co(NO3)2 · 6H2O, Fe(NO3)3 · 9HFO – diol, showed two
exothermic heat effects: at ~343 K,
corresponding to the redox reaction Fe(NO3)3 – diol and at
~ 388 K, due to the
redox reaction Co(NO3)2 – diol. As a result
of these redox reactions, a homogenous mixture of Fe(III) and Co(II) carboxylate
compounds was obtained. These
oxides precursors have been characterized by thermal analysis and FT-IR
spectrometry.
By thermal decomposition of the synthesized precursors at ~ 573 K, followed by
annealing at 673 K, 973 K and 1273
K, CoFe2O4 was obtained as single or predominant nanocrystalline phase depending
on the x value, as evidenced by
XRD analysis.
Keywords: Cobalt ferrite, carboxylates, propanediol, thermal decomposition