Several years ago, we remarked that hard lead-free piezoceramics may enter the market first, before soft lead-free piezoceramics. Indeed, Uchino had stated many years ago that lead-free piezoceramics are more suitable for high-power applications than PZT, as the latter suffers strongly under high-vibration velocities and moderately enhanced temperatures. The goal of hardening is to reduce domain wall motion and thus losses and to make the electromechanical coupling rely primarily on the intrinsic piezoelectric effect.
In this presentation, we reveal the fundamental origin of relaxor ferroelectric-based extremely high texture. Texture is quantified as multiples of a random distribution as evaluated using azimuth-dependent synchrotron assessment. To this end, we contrast poling-induced texture in a variety of NBT-based materials with PZT. The NBT-based materials include NBT-6BT doped with either Zn or Mg. We further include NBT-21KBT into the evaluation. We find that the texture in the NBT-BT- based materials is far superior to the other materials and therefore has little losses due to domain wall motion. This effect is further elaborated by considering texture and phase content of NBT-6BT-0.5 Mg as a function of temperature.
This work is further verified by preparing the same materials with different degrees of poling and assessing remanent polarization vs. piezoelectric coefficient. In addition, we report that NBT-6BT-0.5Zn materials, in contrast to PZT, can be poled to such a high degree that the piezoelectric coefficient starts to drop due to the decrease in the contribution by extrinsic piezoelectric effect.