Influence of Sm³⁺ doping on the relaxation behaviors of KSr₂Nb₅O₁₅ ferroelectric ceramics and the luminescence modulation effect by polarization engineering

The luminescence modulation behavior of lanthanide ion doped materials possesses great potential for applications in sensing, display and anti-counterfeiting devices. Unlike traditional tuning methods for chemical compositions, novel rare-earth doped ferroelectric oxides exhibit attractive luminescence modulation effects via electric polarization engineering, and enrich the development of multifunctional devices. In this work, Sm³⁺ doped KSr₂Nb₅O₁₅ ceramics with abundant ferroelectric and luminescent properties were synthesized. The samples show different relaxation behaviors and ferroelectric features upon chemical and structural factors caused by Sm³⁺ doping, such as average ionic radii, local tolerance factors, and chemical bonds. After polarization at 20 kV/cm for 20 min, a considerable increase (~40%) in the luminescent emission intensity was obtained in 4 mol. % Sm³⁺ doped KSr₂Nb₅O₁₅ ceramics. The related luminescence modulation mechanism was attributed to controlling the environmental symmetry around Sm³⁺ by the electric polarization.