来源：ACS Publications
Relaxor ferroelectric crystals are cornerstone materials for electromechanical and electro-optic technologies, yet the antagonism between piezoelectric performance and optical transparency has persistently impeded device integration. Here, we demonstrate that Sm3+ doping in Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) single crystals shatters this conventional compromise, achieving an exceptional piezoelectric coefficient (d33 = 3500 pC/N) by [001]-poling and a large electro-optic coefficient (γc = 700 pm/V) by [110]-poling while retaining >70% optical transmittance across the visible-near-infrared spectrum. Through multiscale structural analysis, we unveil that Sm3+ incorporation induces lattice contraction and catalyzes the formation of polar nanoregions (PNRs), leading to a polymorphic nanodomain architecture (20–200 nm) that facilitates low-energy polarization rotation and minimizes domain wall pinning. Notably, [110] crystallographic poling is identified as the optimal configuration for balancing an enhanced piezoelectric response (d33 = 1600 pC/N) with superior optical clarity. These crystals concurrently maintain practical thermal stability (TRT > 70 °C) and mechanical quality factors (Qm ≈ 105). Our work establishes rare-earth doping as a universal materials-design strategy for engineering multifunctional ferroelectrics that transcend traditional property limitations.