Dielectric properties of Pb(Fe2/3W1/3)O-3-PbTiO3 solid-solution ceramics

The dielectric properties of (1-x)Pb(Fe2/3W1/3)O-3. xPbTiO(3) solid solutio ns were investigated from 10(2) to 10(6) Hz in the temperature range 150-60 0 K. The phase transition of Pb(Fe2/3W1/3)O-3 (PFW) was shifted by PbTiO3 ( PT) additions to higher temperatures at a rate of 6.3 K/mol% of PT. The tem perature dependence of dielectric permittivity showed a sharper transition as the PT content increased, Dielectric measurements in a wide temperature range showed the presence of a second set of dielectric peaks at higher tem peratures (350-600 K), besides the ferroelectric-paraelectric phase transit ion, This second set of peaks vanished when the samples were annealed in ni trogen. The activation energy values for the second relaxation varied betwe en 0.50 and 0.63 eV, in agreement with the conduction activation energy det ermined for each sample. This relaxation is apparently related to electron holes.