Aging effects upon the temperature dependence of the dielectric permittivity and loss angle tangent were studied in Pb(Mg1/3Nb2/3)0.9Ti0.1O3 and 0.1wt%MnO- Pb(Mg1/3Nb2/3)0.95Ti0.05O3 ceramics. A Debye-like dielectric relaxation process was clearly observed at high temperatures in the latter material, but not in the former. It was found that the metastability of the ferroelectric domain structure was due to the presence of defect dipoles in the perovskite. Defect dipoles were formed from pairs of vacancy and positively charged dopant sites, and provided pinning centres in ferroelectric micro-domain walls. As a result, micro-domains were re-established, in time, along a given direction, and the microstructure changed from disordered to apparently ordered. A perovskite relaxor ferroelectric with acceptor dopants therefore exhibited a significant time-dependent decrease in its complex dielectric response.

The Effect of Defect Field on Dielectric Aging of Lead Magnesium Niobate-Lead Titanate Relaxor Ferroelectrics. H.Fan, L.Zhang, L.Zhang, X.Yao: Journal of Physics - Condensed Matter, 2000, 12[19], 4381-90