The relationships between macro-properties and micro-structure of Pb(Zn_1/3Ni_2/3)_z–Pb(Ni_1/3Nb_2/3)_x–Pb(Zr,Ti)_yO₃ ceramics near morphotropic phase boundary

The phase structure, microstructure and electronic properties of relaxor piezoelectric zPZN–xPNN–yPZT (with x/y = 44/50, 47/47, 50/44) ceramics were researched. The Pb(Zn_1/3Ni_2/3)_z–Pb(Ni_1/3Nb_2/3)_x–Pb(Zr,Ti)_yO₃ composite ceramics have been prepared by a traditional solid-state reaction method. The X-ray diffraction (XRD) shows that all the samples have a pure perovskite structure, the phase structure are changed with the range of PNN/PZT ratios. When PNN/PZT = 47/47, the ceramics have a tetragonal–rhombohedral co-existed phase structure (morphotropic phase boundary), and high piezoelectric constant of 800 pC/N, the remnant polarization (Pr = 14.05 µC/cm²) increased a lot. The other ceramics can not compare to.Furthermore, the results of TEM high resolution images and SAED patterns revealed the ceramics have different phase structures, which further demonstrated the MPB structure is optimum when PNN/PZT = 47/47. The observation of above provide a possible method further to characterize the MPB structure in piezo-ceramics, and this is good for researching the MPB structure.