Formation mechanism, crystallite growth and electrical conductivity of nano-crystalline CuxFe3-xO4 (0.75 less than x less than 1.25) spinels prepared by glycine-nitrate process
Hosseini, S. N.[Seyedeh Narjes], Enayati, M. H.[Mohammad Hossein], Karimzadeh, F.[Fathallah], Sammes, N. M.[Nigel Mark]
The CuxFe3-xO4(0.75 less than x less than 1.25) nano-crystalline powders were prepared by an optimized glycine-nitrate process (GNP) followed by calcination. Thermal analysis and X-ray diffraction (XRD) data revealed that formation of CuFe2O4 takes place in three steps. In the first step, iron and copper nitrates decompose to Fe2O3 and Cu, respectively. Then, Cu changes to CuO and finally CuO reacts with Fe2O3 to form CuFe2O4. The optimized GNP process was then applied on CuxFe3-xO4 spinels to find the optimum x value representing a single phase product with the best conductivity. Electrical measurements in air at 650-800 degC showed that the highest electrical conductivity, among CuxFe3-xO4 spinels, belonged to stoichiometric CuFe2O4 compound (7.6 S cm-1with 1.5% uncertainty at 800 degC). The results of annealing exhibited that the resulting CuFe2O4 spinel is thermally stable and its crystallite growth behavior can be explained by the parabolic grain growth law. The activation energy of the crystallite growth was calculated as 363 kJ mol-1 with 4% uncertainty.
Compounds
#
Formula
Name
1
CuFe2O4
copper ferrite (CuFe2O4)
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.