The effects of La on the dielectric properties of lead iron tungstate Pb(Fe2/3W1/3)O-3 relaxer ceramics

La doped samples were used to study the effects of this dopant on the struc tural and dielectric properties of Pb(Fe2/3W1/3)O-3 (PFW) relaxer ceramics. La doping leads to a decrease in the lattice constant of the cubic PFW per ovskite and to the precipitation of increasing amounts of a second phase, P bWO4. A decrease of dielectric permittivity maximum, epsilon(rmax), a shift of transition temperature, T-0, to lower temperatures, and an increase of diffuseness, delta, are also observed. Undoped and La doped PFW show a p-ty pe conduction. The resistivity vs La content shows a "V-like" curve. The ag ing behavior of the samples are also altered by the presence of the dopant. The aging decreases with increasing the La content up to 5 at% and increas es after that. Charge compensation and defect associations in the La doped samples are discussed and suggested to explain the electrical properties an d the aging behavior. (C) 2000 Elsevier Science Ltd. All rights reserved.