Effects of Cr2O3 addition on the piezoelectric properties and microstructure of PbZrxTiy(Mg1/3Nb2/3)1−x−yO3 ceramics

The effects of the addition of Cr2O3 on the piezoelectric properties and microstructure were investigated for the PbZrxTiy(Mg1/3 Nb2/3)1−x−yO3 (PZTMN) system. The results showed that the Cr2O3 addition was effective in increasing the Kp and Qm, which indicated that Cr-doped PZTMN ceramics possessed, simultaneously, the properties of ‘soft’ and ‘hard’ piezoelectrics. Furthermore, the properties were found to become ‘hard’ with an increase of sintering temperature even for the same compositions. Electron spin resonance (ESR) analysis showed that the Cr ion coexisted in both Cr3+ and Cr5+, and that the valence change from Cr5+ or Cr6+ to Cr3+ happened when the sintering temperature was increased. Transmission electron microscopy (TEM) results showed that, with increasing Cr content, the normal stripe-like domain changed to a wavy domain structure due to domain wall pinning by the defect complexes of acceptor impurities and oxygen vacancies.