Effect of barium on the structure and dielectric properties of multicomponent ceramics based on ferroelectric relaxors

High-density ceramic samples of mPb(Mg1/3Nb2/3) center dot yPb(Zn1/3Nb2/3) center dot nPb(Ni1/3Nb2/3) center dot xPbTiO(3) (m = 0.4541, y = 0.0982, n = 0.1477, x = 0.3) solid solutions, unmodified and barium-modified, with the composition lying in a morphotropic phase region, have been prepared by a conventional ceramic processing technique. We demonstrate that barium substitution for 5% of the lead on the A site allows one to obtain ceramics containing no pyrochlore phase. Modification with barium shifts the solid solution from the morphotropic to a tetragonal phase region. In addition, barium doping increases the average grain size of the ceramic from 2-3 to 3-4 mu m and changes the type of fracture from intergranular to mixed (intergranular and transgranular). Modification with barium increases the relative dielectric permittivity E >/E >(0) (at E = 0) of the material by more than a factor of 2 (from 4300 to 9100). We conclude that materials based on the ceramics studied can find practical application and examine ways of further improving their piezoelectric performance.