Study on the luminescence properties and energy transfer of Na4CaSi3O9:Ce3+, Sm3+ phosphor

In this work, we synthesize successfully Na 4 CaSi 3 O 9 :R (R = Ce 3+ , Sm 3+ , and Ce 3+ /Sm 3+ ) phosphors in the reducing atmosphere (95% N 2  + 5% H 2 ) by using the high-temperature solid-state method. The crystal structure and luminescence properties of samples are investigated. The excitation spectrum of Na 4 CaSi 3 O 9 :Ce 3+ phosphor is observed in the range of 220–400 nm due to the 4 f → 5 d transitions of Ce 3+ ion. The emission spectrum contered at ∼425 nm of Na 4 CaSi 3 O 9 :Ce 3+ phosphor is in the range of 360–650 nm owing to the 5 d → 2 F 5/2 and 2 F 7/2 transitions of Ce 3+ ion. Na 4 CaSi 3 O 9 :Sm 3+ phosphor can show the excitation spectrum in the range of 200–550 nm owing to the O 2− - Sm 3+ charge transfer band and the f - f transitions of Sm 3+ ion, and its emission spectrum covers the region from 575 nm to 750 nm with four emission bands because of the 4 G 5/2  →  6 H 5/2 , 6 H 7/2 , 6 H 9/2 , and 6 H 11/2 transitions of Sm 3+ ion. The tunable emission, luminescence improvement, temperature-dependent emission, and lifetime in Na 4 Ca 0.96-x Si 3 O 9 :4 mol%Ce 3+ , xSm 3+ phosphors are investigated. The luminous mechanism of Na 4 CaSi 3 O 9 :Ce 3+ , Sm 3+ phosphors is explained by using the energy level diagrams of Ce 3+ and Sm 3+ ions. The experimental results are beneficial to research new Ce 3+ and Sm 3+ co-doped phosphors.