Abstract

Characterization of Cobalt Oxides Transformations with Temperature at Different Atmospheres

Author(s): Maria Fernanda Gazulla, Maria Jesus Ventura, Cristina Andreu, Jessica Gilabert, Monica Orduna and Marta Rodrigo

Cobalt is a transition metal with many oxidation states, which results in the formation of different oxides, such as CoO, CoO2, Co2O3, Co3O4, etc. Their exceptional properties generate a great interest in optic, catalysis and ceramic industries, so the deep study of the cobalt oxide transformations with temperature in different atmospheres is the key to improve the industrial processes. The aim of the work was to devise the transformations of the cobalt oxides by undergoing different heating cycles in three atmospheres (air, nitrogen/hydrogen and oxygen) and to carry out a complete characterization of each compound obtained from the treatments. Different materials based on cobalt compounds, such as Co(OH)2, Co°, CoO and Co3O4, have been treated in different atmospheres (air, nitrogen/hydrogen and oxygen), and temperature conditions. The formation of Co3O4 as a product of the treatment of Co(OH)2 under an oxidative atmosphere, the obtaining of CoO and Co° from the thermal treatment of Co3O4 in a reductive atmosphere and the production of Co3O4 from the oxidation of Co° and CoO were studied. All the materials were characterized by determining the cobalt content by WD-XRF, the oxygen concentration by an elemental analyzer and the crystalline phases by XRD and FT-IR.