Dielectric properties of Pb(Fe2/3W1/3)O3-PbTiO3 solid-solution ceramics

The dielectric properties of (1-x)Pb(Fe2/3W1/3)O-3. xPbTiO(3) solid solutions were investigated from 10(2) to 10(6) Hz in the temperature range 150-600 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 temperature 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 temperatures (350-600 K), besides the ferroelectric-paraelectric phase transition, This second set of peaks vanished when the samples were annealed in nitrogen. The activation energy values for the second relaxation varied between 0.50 and 0.63 eV, in agreement with the conduction activation energy determined for each sample. This relaxation is apparently related to electron holes.