Effects of CeO2 Addition on Microstructure and Mechanical Properties of PNW-PMN-PZT Piezoelectric Ceramics

Microstructure and mechanical properties of CeO2 doped Pb0.94Sr0.06 (Ni1/2 W1/2)0.02 (Mn1/3 Nb2/3)0.07 (Zr0.51 Ti0.49)0.91O3 (PNW-PMN-PZT) were investigated. The results indicated that the solution limit of CeO2 was about 5% (mass fraction), and a phase transition from tetragonal to rhombohedral would occur with the increase of the CeO2 dopant. Meanwhile, the tetragonallity also increased with the increase of the CeO2 dopant. Incorporation of CeO2 could suppress the grain growth and increase the remnant strain on the grain surface. Compositional non-homogeneity and serious Fe element segregation at grain boundaries was found due to the doping of CeO2. Owing to brittleness of the glassy phase, the fracture behavior of the materials tended to occur at the Fe-rich grain boundaries. The ceramic with 5% CeO2 addition showed good mechanical properties with the hardness 115 and the flexural strength 112.9 MPa, which should be attributed to the effects of a suitable CeO2 addition on the grain growing, remnant strain and densification.