Photoluminescence properties and energy transfer mechanisms of Na4CaSi3O9: Sm3+, Eu3+ novel orange-red phosphors

Highlights: • The electric dipole-electric dipole interaction dominates energy transfer. • The luminous intensity at 150 °C is 80% of at room temperature when x = 0.04, y = 0.3. • We can obtain the tunable emission from orange to red in co-doped phosphors. • The enhancement in the f-f absorptions of Sm³⁺ with increasing Eu³⁺ concentration. -- Abstract: Sm³⁺ ions doped Na₄CaSi₃O₉ and Sm³⁺-Eu³⁺ co-doped Na₄CaSi₃O₉ novel phosphors were prepared via conventional solid-state reaction method. The structure, photoluminescence (PL) properties and thermostability of samples were investigated in detail. Rietveld refinement and XRD patterns are in good agreement with the structure of Na₄CaSi₃O₉. The phosphors can be effectively excited by 405 nm irradiation to produce light emission. Under the excitation of 405 nm irradiation, the Na₄CaSi₃O₉: Sm³⁺ phosphors show three broadband emission centered at about 564 nm, 603 nm and 650 nm due to the ⁴G_5/2→⁶H_J (J = 5/2,7/2,9/2) forbidden transition of Sm³⁺ ions and the Sm³⁺-Eu³⁺ co-doped Na₄CaSi₃O₉ phosphors show yellow broadband emission centered at about 564 nm and an orange-red emission band at 592 nm and 613 nm, due to the ⁴G_5/2 → ⁶H_5/2 transition of Sm³⁺ ions and the ⁵D₀→⁷F₁, ⁵D₀→⁷F₂ transition of Eu³⁺ ions, respectively. The energy transfer mechanism between Sm³⁺ and Eu³⁺ ions is electric dipole-electric dipole interaction. The temperature-dependent luminescent properties of Na₄CaSi₃O₉:Sm³⁺, Eu³⁺ ions are measures from 30 °C to 210 °C, and the results show that the luminous intensity of sample at 150 °C is up to 80% of that at room temperature, which indicate that the phosphor has good thermal stability. The above results show that this series of phosphors will have potential applications in near-UV excited white LEDs.