Improved electrical properties and good thermal luminescent stability of Sm³⁺-doped Sr_1.90Ca_0.15Na_0.90Nb₅O₁₅ multifunctional ceramics

Sm³⁺ doped Sr_1.90Ca_0.15Na_0.9Nb₅O₁₅ (SCNN: xSm³⁺) multifunctional ferroelectric ceramics with pure tetragonal tungsten bronze phase were synthesized via the conventional solid-state reaction method. The dielectric, ferroelectric characteristics and luminescent behaviors were systematically studied. The electrical properties suggested that a moderate Sm³⁺ doping could enhance the electrical performances. The orange-reddish emission originated from the transition of ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 → ⁶H_5/2 and ⁴G_5/2 → ⁶H_9/2 was observed under excitation wave of 406 nm. The strongest emission intensities were obtained at the Sm³⁺ doping content of 0.010. The degree of thermal quenching for the composition with x = 0.010 was relatively lower and the normalized emission intensity continued still 80% from room temperature to 150 °C. Besides, the transmittance in visible spectra of the SCNN: xSm³⁺ ceramics could be improved obviously, which was up to 50% at the doping amount of 0.010. These results show that the SCNN: xSm³⁺ multifunctional ferroelectric niobates have promising potential in electric-optical devices.