Processing and properties of relaxor-type ferroelectric Pb(Sc1/2Nb1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3 perovskite ceramics

Relaxor-type ferroelectric Pb(Sc1/2Nb1/2)O-3-Pb(Ni1/3Nb2/3)O-3-PbTiO3 (PSN-PNN-PT) perovskites were prepared through two-steps process consisting of heat treatment and then acid treatment of oxide mixtures containing PbO in amount greater than in the perovskite composition. The dielectric and electromechanical behaviors were examined for the (1-x)(6PNN-4PSN)-xPT and (1-x)(4PNN-6PSN)-xPT ceramics. In both the series, relaxor behavior was remarkable in the PNN-richer side. With increasing x value, the dielectric constant-temperature curve turned form broad to sharp, the dielectric constant at the peak increased and the peak position shifted toward higher temperature side. The field-induced strain mode underwent a change from electrostrictive mode to piezoelectric mode via electrostrictive-piezoelectric overlapping mode as increasing x value. The (1-x)(6PNN-4PSN)-xPT series rather resulted in the higher field-induced strain than the (1-x)(4PNN-6PSN)-xPT series. The composition 48PNN-32PSN-20PT showed strain of 0.125% at room temperature under 1500V/mm, due to electrostrictive-piezoelectric effect, which was the highest among observed.