Kinetics of formation of RuSr2GdCu2O8 by solid-state reaction of Sr2GdRuO6 and CuO

The reaction process for the formation of RuSr2GdCu2O8 (Ru-1212) through the precursor route is investigated using differential thermal analysis (DTA) and X-ray powder diffraction (XRD) methods. The results clearly show that no impurity phase is produced in this reaction. Using the integral method to analyze the XRD data of sintered samples, it is found that the solid-state reaction for the formation of Ru-1212 through the precursor route is associated with the diffusion mechanism. The activation energy of 527±44 kJ/mol obtained from the XRD analysis is in close agreement to that estimated from the DTA result, with a deviation of less than 5%. A pre-exponential factor k0 of (4.47±0.06) × 1017 /min is obtained for this solid-state reaction. © 2002 Elsevier Science B.V. All rights reserved.