Alkaline Earth Substituting Induced MPB Evolution and Property Enhancement in Pb(Mg_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃:Sm

In this work, based on the lanthanide rare earth Sm 3+ doped 0.2Pb(Mg 1/3 Nb 2/3 )O 3 -(0.8- x )PbZrO 3 - x PbTiO 3:0.015Sm ceramics with a rhombohedral-tetragonal morphotropic phase boundary (MPB) around x = 0.40, we gradually introduced alkaline earth Ba 2+ and Sr 2+ at the A-site to substitute Pb 2+, namely, 0.2 A (Mg 1/3 Nb 2/3 )O 3 -0.4 A ZrO 3 -0.4 A TiO 3:0.015Sm ( A = Pb 0.99- y Ba 0.01 Sr y ) 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 d 33 = 477 pC/N and electromechanical coupling factor k p = 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 d 33 = 687 pC/N and k p = 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.