Elastic softening and polarization memory in PZN-PT relaxor ferroelectrics

Substantial elastic softening in the cubic phase of PZN-PT relaxor ferroelectric crystals is observed as a large hysteresis between the RUS frequencies from poled and depoled crystals. This is due to static switchable polar nanoregions (PNR) at T ^*, well below the conventional Burns temperature but ~50 K above the ferroelectric transition. Elastic softening due to polarization of the PNR shows polarization memory through two phase transitions and is greater than the softening associated with polarization of the ferroelectric phases. This emphasizes that PNR dominate the material properties at all temperatures below T^*.