Structural and electrical properties of ZnO-modified (1?x)Pb(Mg1/3Nb2/3)O3?xPbTiO3 ceramics with wide MPB regions

Ferro-/piezoelectric ceramics with high performances are generally found at the morphotropic phase boundary (MPB), where two or more different ferroelectric phases coexist. However, the MPB region is usually very narrow; for example, that of (1?x)Pb(Mg_1/3Nb_2/3)O₃?xPbTiO₃ (PMN-xPT) locates between x = 0.30?0.34. Herein, we report that ZnO-modified PMN-xPT polycrystalline ceramics have dramatically broadened MPB regions from x = 0.28, with rhombohedral and monoclinic coexisting phases, to x = 0.36, with tetragonal and monoclinic coexisting phases, as confirmed by powder X-ray diffraction and piezoresponse force microcopy measurements. The wide MPB region is attributed to lattice distortion caused by the substitution of Zn for Mg cations. As a result, the ceramics show composition insensitive electrical properties over wide composition ranges; for example, the piezoelectric coefficient (d₃₃) and electromechanical coupling factor (k_p) remain at near constant values of 450 pC/N and 0.5, respectively, in the range from x = 0.28?0.34. This work not only provides a robust and feasible method to broaden the MPB region but also offers some novel insights into promoting fundamental research on high-performance piezoelectric ceramics.