Structural and electrical properties of ZnO‐modified (1−x)Pb(Mg_1/3Nb_2/3)O₃−xPbTiO₃ ceramics with wide MPB regions

Abstract

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(Mg1/3Nb2/3)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 (kp) 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.