Dielectric and piezoelectric properties of (La, Mg, F) and (Mg, Mn, F) doped PZT ceramics under low and high sollicitations

The hysteretic behavior of the charge coefficient d33 under high mechanical stress and of frequency constant N33 during the temperature cycle −40°C–+80°C can be cancelled by fluorine oxygen substitution in the lattice of Mg-doped PZT. These fluorine doped materials also exhibit a high mechanical quality factor and low dielectric losses. The drawback is that they have a lower d33 coefficient and are difficult to pole. Mn doping in B site or La doping in A site, in the ABO3 type perovskite structure are known to increase the d33 coefficient and the poling ability. This result is observed on (Mg, F) co-doped PZT with Mn and with La content of 1.5 mol%. In the same manner, Mn doping enhances the hysteretic behavior and the losses while La doping does not significally changes the (Mg, F) co-doped PZT characteristics except the fluorine content for which the losses and the hysteresis are the lowest.