On the diffusion of Ce into Eu2CuO4-y compounds

The diffusion of Ce in polycrystalline samples of Eu2-xCexCuO4-y (0.0 less than or equal to x less than or equal to 0.18) prepared from a sol-gel precursor and sintered at several temperatures 150 degrees C less than or equal to T less than or equal to 950 degrees C was investigated. The results of X-ray powder diffraction revealed that complete diffusion of Ce into the Eu2CuO4-y matrix occurs in samples sintered at T = 950 degrees C, which is below the eutectic temperature. It was also observed that the Ce diffusion monotonically increases with increasing x, suggesting that the Eu2-xCexCuO4-y (0.0 less than or equal to x less than or equal to 0.18) system forms a true chemical solid solution. The solubility limit of Ce in this series was found to be close to x = 0.15. An accurate analysis of the full width at half maximum of the X-ray diffraction peaks reveals an inhomogeneous Ce distribution in samples sintered for short time intervals. An improvement of the homogeneity of Ce was found in samples sintered for longer times. Results of differential thermal analysis and thermogravimetry were found to be in complete agreement with the X-ray diffraction data. We also found that the peritectic temperature T-p increases with increasing Ce content in this series.