Processing and properties of (1 − x)Pb(Mg1/3Nb2/3)O3·xPbTiO3 solid solutions from PbO- and MgO-excess compositions

Perovskite solid solutions (1 − x)Pb(Mg1/3Nb2/3)O3·xPbTiO3 with x between 0.06 and 0.14 were prepared by heat treatment followed by acid treatment of mixtures containing both PbO and MgO in amounts greater than in the perovskite composition. For example, heat treatment of 4PbO + 1.5MgO + 0.9Nb2O5 + 0.3TiO2 mixture at 900°C for 1 h produced the perovskite with x = 0.1 without the formation of pyrochlore phase. The Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) solid solutions were crystallized into discrete cubes several micrometers in size. After sintering these particles at 1290°C for 2 h in a PbO atmosphere, the relative density of the ceramics was 93% or more. The ceramics with x = 0.08–0.1 showed a large electric field–induced strain near room temperature.