Abstracts Book - IMRC 2018

• SC1-P011
STUDY OF THE PEROVSKITE LaFe0,2Co0,8-XCrXO3 (x = 0.0, 0.2, 0.4,
0.6, 0.8) AS ANODE IN SOLID OXIDE FUEL CELLS
Wilson Rativa Parada 1 , Jairo Gomez Cuaspud 2 , Enrique Vera Lopez 1 , Yaneth Pineda Triana 1 ,
Juan Carda 3
1 Universidad Pedagógica y Tecnológica de Colombia, Metallurgical Engineering, Colombia.
2 Universidad Pedagógica y Tecnológica de Colombia, Chemistry, Colombia. 3 Universitat Jaume
I, Chemistry, Spain.
The work is focused on the synthesis and characterization of five compositions
based on LaCrO3 perovskite modified with Fe and Co using a combustion
method. The starting reagents were nitrates of La(NO3)33H2O 99.9%,
Cr(NO3)39H2O 99.9%, Fe(NO3)39H2O 99.9% Co(NO3)39H2O 99.9% and citric acid
(2.00 M). The corresponding solutions were heated at 100°C to allow that
dissolutions of citrate species were obtained. The systems were progressively
treated at 350 °C until solid foams were formed. The increase in thermal
treatment produces a combustion process that consolidates the oxides, which
were calcined for 12 hours at 850°C to remove carbon residues derived previous
stages. The structural characterization of oxides using X-ray diffraction (XRD)
confirms the formation of a single predominant phase in each case, consistent
with a characteristic structure for perovskite type structures, without evidence
of secondary phases. The samples presented a transformation of a
rhombohedral structure (R3-c) (JCPDS = 01-089-0478) to an orthorrhombic
structure (Pnma 62) (JCPDS = 00-48-0123). This was associated to the mixed
valence of cobalt (Co 2+ = 0.82 Å and Co 3+ = 0.64 Å) and its increase in the atomic
lattice. A crystalline size of 30 nm was calculated the Debye-Scherrer equation
in all samples. The electrical study as a function of the temperature reveal that
the cobalt modification produces a decrease of electrical resistance throughout
all materials as the temperature increases. This is attributed to the progressive
reduction of the chromium content and the presence of a thermal excitation
phenomenon, indicating that temperature propitiate a charge carrier mobility
across the B-O-B bonds according to semiconductor characteristic of these
perovskites. All samples presented small values of activation energy, which
confirms that electronic species are the responsible for the electrical
conductivity in the obtained oxides
Acknowledgment: