Alkaline Earth Substituting Induced MPB Evolution and Property Enhancement in Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3:Sm

In this work, based on the lanthanide rare earth Sm3+ doped 0.2Pb(Mg1/3Nb2/3)O3-(0.8-x)PbZrO3-xPbTiO3:0.015Sm ceramics with a rhombohedral-tetragonal morphotropic phase boundary (MPB) around x = 0.40, we gradually introduced alkaline earth Ba2+ and Sr2+ at the A-site to substitute Pb2+, namely, 0.2A(Mg1/3Nb2/3)O3-0.4AZrO3-0.4ATiO3:0.015Sm (A = Pb0.99-yBa0.01Sry) and conducted a systematic study on their phase structure, domain configuration, and electrical properties. The results indicate that without alkaline earth substituting, the MPB composition shows peak electrical property with piezoelectric coefficient d33 = 477 pC/N and electromechanical coupling factor kp = 0.59, while an appropriate amount of alkaline earth substituting changes the MPB from rhombohedral–tetragonal coexisting phases to rhombohedral–monoclinic–tetragonal coexisting phases, leading to a significant enhancement in electrical properties with d33 = 687 pC/N and kp = 0.63 around y = 0.03 for comparison. This work classifies the mechanism for alkaline earth substituting enhanced piezoelectric performance and may provide a guide for the development of high-performance lead-based relaxor ferroelectrics.