Effects of Cr_2O_3 Addition on the Properties of PZT-PMN Ceramics

The effects of Cr_2O_3 addition on piezoelectric properties, microstructure and morphology of the domain of PZT-PMN ceramics were studied by TEM, SEM, ESR and other conventional electrical methods. The measurement results of piezoelectric properties showed that the Cr2O3 addition was effective in increasing the Kp and Qm when its concentration was below 0.06wt%, which indicated that Cr-doped PZTMN ceramics possessed the properties of“soft” and “hard” piezoelectrics simultaneously. Furthermore, the properties were found to get hard with the increase of sintering temperature even for the ceramics With the same compositions. Electron Spin Resonance (ESR) analysis showed that Cr ion coexisted in both Cr3+ and Cr5+, and the valence change from Cr5+ or Cr6+ to Cr3+ happened when the sintering temperature was increased, which was believed to be one of the reasons for its hardness of the properties. TEM images revealed that, with the increment in Cr content, the normal stripe-like domain changed to wavy domain due to the domain pinning by the defect complexes of acceptor impurities and oxygen vacancies.