Electrical conductivity of Y2O3-doped CeO2 based composite ceramics by spark plasma sintering: The effects of a second phase of CeAlO3

The Ce0.85Y0.15O2-delta (YDC)-xmol% aluminum containing compound (x = 0, 10, 20 and 40) composite powders were prepared through mixing YDC with 0, 10, 20 and 40 mol% Al(NO3)(3) (named as A0, A10, A20, A40), and then densified by spark plasma sintering at 1300 degrees C for 5 min. The main phase of YDC exists in all samples, while a second phase of CeAlO3 forms for x >= 10 in the composite ceramics. The diffraction peak intensity of CeAlO3 gradually augments with the increase of Al(NO3)(3) addition amount. The average grain size of the composite ceramics reduces from 1.7 mu m to 0.34 mu m with the rise in Al(NO3)(3) addition amount from 0 to 40%. The grain boundary (GB) electrical conductivity of A10 and A20 is lowered by 96% and 89% compared with that of YDC at 350 degrees C because the CeAlO3 phase exists in the form of flakes and fine grains and hinders the oxygen ion conduction across the GB of samples. When CeAlO3 grains grow up and uniformly distribute in the A40, the GB conductivity of A40 increases by 405% relative to that of pure YDC at 350 degrees C.

Automated summary

In this study, composite powders of Ce0.85Y0.15O2-delta (YDC)-xmol% aluminum compound were prepared by mixing YDC with different amounts of Al(NO3)(3) and densified through spark plasma sintering. The formation of CeAlO3 phase and reduction in grain size were observed with increasing Al(NO3)(3) addition amount. While the presence of CeAlO3 phase in A10 and A20 samples decreased the grain boundary conductivity, the evenly distributed CeAlO3 grains in A40 led to a significant increase in grain boundary conductivity.