A study on the thermal decomposition of iron-cobalt mixed hydroxides

Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics of isothermal decomposition and electrical conductivity measurements. The thermal products were characterized by X-ray diffraction and IR spectroscopy. The TG and DTA analysis revealed the presence of Co2+ retards the decomposition of ferric hydroxide and the formation of α-Fe2O3. The kinetics of decomposition showed that the mixed samples need higher energy to achieve thermolysis. The investigation of thermal products of mixed samples indicated the formation of cobalt ferrite on addition ofx=1 or 1.5 cobalt hydroxide. The electrical conductivity accompanying the thermal decomposition decreases in presence of low ratio of Co2+ (x=0.2) via the consumption of holes created during thermal analysis. The continuous increase in σ values on increasing of Co2+ concentration corresponded to the electron hopping between Fe2+ and Co3+.