Alkaline Earth Substituting Induced MPB Evolution and Property Enhancement in Pb(MgNb)O-PbZrO-PbTiO:Sm.

In this work, based on the lanthanide rare earth Sm doped 0.2Pb(MgNb)O-(0.8-)PbZrO-PbTiO:0.015Sm ceramics with a rhombohedral-tetragonal morphotropic phase boundary (MPB) around = 0.40, we gradually introduced alkaline earth Ba and Sr at the A-site to substitute Pb, namely, 0.2(MgNb)O-0.4ZrO-0.4TiO:0.015Sm ( = PbBaSr) 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 = 477 pC/N and electromechanical coupling factor = 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 = 687 pC/N and = 0.63 around = 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.