PHASE EVOLUTION WITH THERMAL-TREATMENT IN THE SYSTEM CORDIERITE-CUO

The crystallization temperature of cordierite obtained from a sol-gel route is reduced in presence of CuO, according to the copper tendency to adopt a regular octahedral environment. Structure refinements from powder diffraction data reveal that Cu2+ ions substitute for Mg2+ ones in the octahedral sites of alpha-cordierite. Mg/Cu ratio decreases wi th increasing annealing temperature in agreement with previous results concerning the temperature evolution of ESR spectra. The reaction of CuO with cordierite precursor also explains the peculiar behaviour of the metal-ceramic interface of copper-cordierite cofired samples.