Low temperature sintering and high piezoelectric properties of strontium doped PNZT–PNN ceramics processed via the columbite route

This study investigated the influence of strontium doping on both the sintering behavior and the piezoelectric properties of PNZT–PNN ceramics. The piezoelectric ceramics was produced by solid state reaction between metallic oxides, strontium carbonates (SrCO3) and oxides precursors. NiNb2O6 precursors were mixed with the oxides to avoid the large-scale formation of pyrochlore phases during the sintering process and to favor the formation of the perovskite structure. Sintering experiments were accomplished between 900 °C and 1100 °C for PNZT–PNN with 0–4 mol% strontium. Dilatometer curves indicated that the densification of these samples occurs by 850 °C and the electromechanical characterization showed that strontium doping enhances the soft piezoelectric properties of the PZT–PNN ceramics.Consequently, a sintering temperature of 900 °C is sufficient to obtain doped PZT–PNN tablets with 99% of the theoretical density and excellent soft piezoelectric properties (ɛr > 4000; Kp > 60; d33 > 1000 pm/V). This makes those ceramics suitable for the construction of high efficiency actuators with low sintering temperature. The low Curie temperature is the only drawback of this material for some applications such as engine fuel injection.