Low-temperature densification and grain growth of Bi2O3-doped-ceria gadolinia ceramics

• Published in: Solid state ionics 2007-03, Vol.178 (5-6), p.359-365
• Main Authors: GIL, V, MOURE, C, DURAN, P, TARTAJ, J
• Format: Article
• Language: English
• ISSN: 0167-2738
• DOI: 10.1016/j.ssi.2007.02.002

The effect of small amounts ( < =2.0wt.%) of Bi2O3 on the sintering characteristics and grain growth of cerium oxide doped with gadolinium oxide has been evaluated. The temperature of the shrinkage-rate maximum decreased by almost 300 deg C in the case of the doped gadolinia-modified ceria, (GDC) containing 2.0wt.% Bi2O3. An apparent density > 99% of the theoretical density (Dth) has been achieved on sintering at 1400 deg C for 4h for GDC containing 1.0wt.% Bi2O3 and of the order of 97.9% on sintering for 2h for GDC containing 0.5wt.% Bi2O3. The grain growth kinetics have been studied in terms of the kinetic grain growth equation: Dn=Kot exp (-Q/RT) for sintering in air from 1400 deg to 1550 deg C. The apparent activation energy for the grain growth of GDC increased to about 892KJ/mol from 518KJ/mol for undoped-GDC. This result may indicate that additions of Bi2O3 retard the grain growth of GDC ceramics. The conductivity of 1wt.% doped samples has been measured by complex impedance spectroscopy (CIS). Doping with Bi2O3 does not modify the conductivity of the GDC solid solution.